Emotions and Experience of Rewards
Course psychology
Lifespan Development
book
Santrock, J. W. (2019). Life-span development (17th ed.). New York, NY: McGraw-Hill Education.
Week 4 Assignment: The Adolescent Brain – Workshop Handout
Required Resources
Read/review the following resources for this activity:
- Textbook: Chapter 11
- Lesson
- Minimum of 2 scholarly sources (in addition to course text)
Instructions
Your textbook details a sequence in which the human brain develops. The limbic system, or the seat of emotions and experience of rewards, (p. 344) is said to be completely developed in early adolescence. However, the pre-frontal cortex, also called the, judgement region doesn’t finish developing until at least a person is nearly an adult.
We could reasonably suggest that during the adolescent stage, it may be biologically difficult for a person to wrangle their emotions, impulses, and behaviors.
As a medical educator, how would you teach a group of parents about why their adolescent boys and girls are “acting out”?
In approximately 3 pages, create a “fact sheet” in MS Word that includes a chart, images, or banners, tables, etc., that explain why adolescent children may be less logical and more emotional in their decision-making. As part of your fact sheet, include ideas on how parents can best support their teenager during this time
Be sure that you use peer-reviewed research and the textbook to support your 3-page handout.
Writing Requirements (APA format)
- Length: 2.5-3 pages (not including title page or references page)
- Includes engaging presentation elements (i.e. images, banners, tables)
- Attributes proper credit to outside sources (due to the creative nature of this assignment, attribution may look different than it does in a standard essay – that is ok so long as you credit your source in such a way that your audience can easy track down the sources you reference)
Grading
This activity will be graded using the Essay Grading Rubric. Please review the following link:
Link (webpage):
Course Outcomes (CO): 1, 3, 4, 5
Due Date: By 11:59 p.m. MT on Sunday
Rubric
PSYC290 Week 4 Assignment
| PSYC290 Week 4 Assignment | |||||||
| Criteria | Ratings | Pts | |||||
| This criterion is linked to a Learning OutcomeAssignment Content |
|
60.0 pts | |||||
| This criterion is linked to a Learning OutcomeResearch |
|
20.0 pts | |||||
| This criterion is linked to a Learning OutcomeProfessional Communication |
|
20.0 pts | |||||
| Total Points: 100.0 | |||||||
chapter 11
PHYSICAL AND COGNITIVE DEVELOPMENT IN ADOLESCENCE
chapter outline
Learning Goal 1 Discuss the nature of adolescence.
Learning Goal 4 Explain cognitive changes in adolescence.
Learning Goal 5 Summarize some key aspects of how schools influence adolescent development.
The Transition to Middle or Junior High School
Effective Schools for Young Adolescents
©Image Source/Getty Images
Fifteen-year-old Latisha developed Page 338a drinking problem, and she was kicked off the cheerleading squad for missing too many practice sessions—but that didn’t make her stop drinking. She and her friends began skipping school regularly so they could drink.
Fourteen-year-old Arnie is a juvenile delinquent. Last week he stole a TV set, struck his mother and bloodied her face, broke some streetlights in the neighborhood, and threatened a boy with a wrench and hammer.
Twelve-year-old Katie, more than just about anything else, wanted a playground in her town. She knew that the other kids also wanted one, so she put together a group that generated funding ideas for the playground. They presented their ideas to the town council. Her group attracted more youth, and they raised money by selling candy and sandwiches door-to-door. The playground became a reality, a place where, as Katie says, “People have picnics and make friends.” Katie’s advice: “You won’t get anywhere if you don’t try.”
Adolescents like Latisha and Arnie are the ones we hear about the most. But there are many adolescents like Katie who contribute in positive ways to their communities and competently make the transition through adolescence. Indeed, for most young people, adolescence is not a time of rebellion, crisis, pathology, and deviance. A far more accurate vision of adolescence is that it is a time of evaluation, decision making, commitment, and carving out a place in the world. Most of the problems of today’s youth are not with the youth themselves, but with needs that go unmet. To reach their full potential, adolescents need a range of legitimate opportunities as well as long-term support from adults who care deeply about them (Miller & Cho, 2018; Ogden & Haden, 2019).
Katie Bell (front) and some of her volunteers.
©Ronald Cortes
topical connections looking back
In middle and late childhood, physical growth continues but at a slower pace than in infancy and early childhood. Gross motor skills become much smoother and more coordinated, and fine motor skills also improve. Significant advances in the development of the prefrontal cortex occur. Cognitive and language skills also improve considerably. In terms of cognitive development, most children become concrete operational thinkers, long-term memory increases, and metacognitive skills improve, especially if children learn a rich repertoire of strategies. In terms of language development, children’s understanding of grammar and syntax increases, and learning to read becomes an important achievement.
preview
Adolescence is a transitional period in the human life span, linking childhood and adulthood Page 339. We begin the chapter by examining some general characteristics of adolescence and then explore the major physical changes and health issues of adolescence. Next, we consider the significant cognitive changes that characterize adolescence and conclude the chapter by describing various aspects of schools for adolescents.
1 The Nature of Adolescence
LG1 Discuss the nature of adolescence.
As in development during childhood, genetic/biological and environmental/social factors influence adolescent development. During their childhood years, adolescents experienced thousands of hours of interactions with parents, peers, and teachers, but now they face dramatic biological changes, new experiences, and new developmental tasks. Relationships with parents take a different form, moments with peers become more intimate, and dating occurs for the first time, as do sexual exploration and possibly intercourse. The adolescent’s thoughts become more abstract and idealistic. Biological changes trigger a heightened interest in body image. Adolescence has both continuity and discontinuity with childhood.
There is a long history of worrying about how adolescents will “turn out.” In 1904, G. Stanley Hall proposed the “storm-and-stress” view that adolescence is a turbulent time charged with conflict and mood swings. However, when Daniel Offer and his colleagues (1988) studied the self-images of adolescents in the United States, Australia, Bangladesh, Hungary, Israel, Italy, Japan, Taiwan, Turkey, and West Germany, at least 73 percent of the adolescents displayed a healthy self-image. Although there were differences among them, the adolescents were happy most of the time, they enjoyed life, they perceived themselves as able to exercise self-control, they valued work and school, they felt confident about their sexual selves, they expressed positive feelings toward their families, and they felt they had the capability to cope with life’s stresses—not exactly a storm-and-stress portrayal of adolescence.
Public attitudes about adolescence emerge from a combination of personal experience and media portrayals, neither of which produces an objective picture of how normal adolescents develop (Feldman & Elliott, 1990). Some of the readiness to assume the worst about adolescents likely involves the short memories of adults. Many adults measure their current perceptions of adolescents by their memories of their own adolescence. Adults may portray today’s adolescents as more troubled, less respectful, more self-centered, more assertive, and more adventurous than they were.
Growing up has never been easy. However, adolescence is not best viewed as a time of rebellion, crisis, pathology, and deviance. A far more accurate vision of adolescence describes it as a time of evaluation, of decision making, of commitment, and of carving out a place in the world. Most of the problems of today’s youth are not with the youth themselves. What adolescents need is access to a range of legitimate opportunities and to long-term support from adults who care deeply about them. What might be some examples of such support and caring?
©Regine Mahaux/The Image Bank/Getty Images
However, in matters of taste and manners, the young people Page 340of every generation have seemed unnervingly radical and different from adults—different in how they look, in how they behave, in the music they enjoy, in their hairstyles, and in the clothing they choose. It would be an enormous error, though, to confuse adolescents’ enthusiasm for trying on new identities and enjoying moderate amounts of outrageous behavior with hostility toward parental and societal standards. Acting out and boundary testing are time-honored ways in which adolescents move toward accepting, rather than rejecting, parental values.
Negative stereotyping of adolescence has been extensive (Jiang & others, 2018; Petersen & others, 2017). However, much of the negative stereotyping has been fueled by media reports of a visible minority of adolescents. In the last decade there has been a call for adults to have a more positive attitude toward youth and emphasize their positive development. Indeed, researchers have found that a majority of adolescents are making the transition from childhood through adolescence to adulthood in a positive way (Seider, Jayawickreme, & Lerner, 2017). For example, a recent study of non-Latino White and African American 12- to 20-year-olds in the United States found that they were characterized much more by positive than problematic development, even in their most vulnerable times (Gutman & others, 2017). Their engagement in healthy behaviors, supportive relationships with parents and friends, and positive self-perceptions were much stronger than their angry and depressed feelings.
©RubberBall Productions/Getty Images
Although most adolescents negotiate the lengthy path to adult maturity successfully, too large a group does not. Ethnic, cultural, gender, socioeconomic, age, and lifestyle differences influence the actual life trajectory of each adolescent (Green & others, 2018; Hadley, 2018; Kimmel & Aronson, 2018; McQueen, 2017; Ruck, Peterson-Badali, & Freeman, 2017). Different portrayals of adolescence emerge, depending on the particular group of adolescents being described. Today’s adolescents are exposed to a complex menu of lifestyle options through the media, and many face the temptations of drug use and sexual activity at increasingly young ages (Johnston & others, 2018). Too many adolescents are not provided with adequate opportunities and support to become competent adults (Bill & Melinda Gates Foundation, 2018; Edalati & Nicholls, 2018; Lo & others, 2017; Loria & Caughy, 2018; Miller & Cho, 2018; Umana-Taylor & Douglass, 2017).
Recall that social policy is the course of action designed by the national government to influence the welfare of its citizens. Currently, many researchers in adolescent development are designing studies that they hope will lead to wise and effective social policy decision making (Duncan, Magnuson, & Votruba-Drzal, 2017; Galinsky & others, 2017; Hall, 2017).
Research indicates that youth benefit enormously when they have caring adults in their lives in addition to parents or guardians (Frydenberg, 2019; Masten, 2017; Masten & Kalstabakken, 2018; Ogden & Hagen, 2019; Pomerantz & Grolnick, 2017). Caring adults—such as coaches, neighbors, teachers, mentors, and after-school leaders—can serve as role models, confidants, advocates, and resources. Relationships with caring adults are powerful when youth know they are respected, that they matter to the adult, and that the adult wants to be a resource in their lives. However, in a survey, only 20 percent of U.S. 15-year-olds reported having meaningful relationships with adults outside their family who were helping them to succeed in life (Search Institute, 2010).
Review Connect Reflect
LG1 Discuss the nature of adolescence.
Review
- What characterizes adolescent development? What especially needs to be done to improve the lives of adolescents?
Connect
- In this section you read about how important it is for adolescents to have caring adults in their lives. In previous chapters, what did you learn about the role parents play in their children’s lives leading up to adolescence that might influence adolescents’ development?
Reflect Your Own Personal Journey of Life
- Was your adolescence better described as a stormy and stressful time or as one of trying out new identities as you sought to find an identity of your own? Explain.
Page 341
2 Physical Changes
LG2 Describe the changes involved in puberty, as well as changes in the brain and sexuality during adolescence.
Puberty
The Brain
Adolescent Sexuality
One father remarked that the problem with his teenage son was not that he grew, but that he did not know when to stop growing. As we will see, there is considerable variation in the timing of the adolescent growth spurt. In addition to pubertal changes, other physical changes we will explore involve sexuality and the brain.
PUBERTY
Puberty is not the same as adolescence. For most of us, puberty ends long before adolescence does, although puberty is the most important marker of the beginning of adolescence.
Puberty is a brain-neuroendocrine process occurring primarily in early adolescence that provides stimulation for the rapid physical changes that take place during this period of development (Berenbaum, Beltz, & Corley, 2015; Shalitin & Kiess, 2017; Susman & Dorn, 2013). Puberty is not a single, sudden event. We know whether a young boy or girl is going through puberty, but pinpointing puberty’s beginning and end is difficult. Among the most noticeable changes are signs of sexual maturation and increases in height and weight.
Sexual Maturation, Height, and Weight Think back to the onset of your puberty. Of the striking changes that were taking place in your body, what was the first to occur? Researchers have found that male pubertal characteristics typically develop in this order: increase in penis and testicle size, appearance of straight pubic hair, minor voice change, first ejaculation (which usually occurs through masturbation or a wet dream), appearance of kinky pubic hair, onset of maximum growth in height and weight, growth of hair in armpits, more detectable voice changes, and, finally, growth of facial hair.
What is the order of appearance of physical changes in females? First, either the breasts enlarge or pubic hair appears. Later, hair appears in the armpits. As these changes occur, the female grows in height and her hips become wider than her shoulders. Menarche—a girl’s first menstruation—comes rather late in the pubertal cycle. Initially, her menstrual cycles may be highly irregular. For the first several years, she may not ovulate every menstrual cycle; some girls do not ovulate at all until a year or two after menstruation begins. No voice changes comparable to those in pubertal males occur in pubertal females. By the end of puberty, the female’s breasts have become more fully rounded.
Marked weight gains coincide with the onset of puberty. During early adolescence, girls tend to outweigh boys, but by about age 14 boys begin to surpass girls. Similarly, at the beginning of the adolescent period, girls tend to be as tall as or taller than boys of their age, but by the end of the middle school years most boys have caught up or, in many cases, surpassed girls in height.
As indicated in Figure 1, the growth spurt occurs approximately two years earlier for girls than for boys. The mean age at the beginning of the growth spurt in girls is 9; for boys, it is 11. The peak rate of pubertal change occurs at 11½ years for girls and 13½ years for boys. During their growth spurt, girls increase in height about 3½ inches per year, boys about 4 inches. Boys and girls who are shorter or taller than their peers before adolescence are likely to remain so during adolescence; however, as much as 30 percent of an individual’s height in late adolescence is unexplained by his or her height in the elementary school years.
FIGURE 1 PUBERTAL GROWTH SPURT. On average, the peak of the growth spurt during puberty occurs two years earlier for girls (11½) than for boys (13½). How are hormones related to the growth spurt and to the difference between the average height of adolescent boys and that of girls?
Is age of pubertal onset linked to how tall boys and girls will be toward the end of adolescence? One study found that for girls, earlier onset of menarche, breast development, and growth spurt were linked to shorter height at 18 years of age; however, for boys, earlier age of growth spurt and slower progression through puberty were associated with being taller at 18 years of age (Yousefi & others, 2013).
Hormonal Changes Behind the first whisker in boys and the widening of hips in girls is a flood of hormones, powerful chemical substances secreted by the endocrine glands and carried through the body by the bloodstream.
The concentrations of certain hormones Page 342increase dramatically during adolescence (Berenbaum, Beltz, & Corley, 2015; Herting & Sowell, 2017; Nguyen, 2018; Piekarski & others, 2017). Testosterone is a hormone associated in boys with genital development, increased height, and deepening of the voice. Estradiol is a type of estrogen that in girls is associated with breast, uterine, and skeletal development. In one study, testosterone levels increased eighteenfold in boys but only twofold in girls during puberty; estradiol increased eightfold in girls but only twofold in boys (Nottelmann & others, 1987). Thus, both testosterone and estradiol are present in the hormonal makeup of both boys and girls, but testosterone dominates in male pubertal development, estradiol in female pubertal development (Benyi & Savendahl, 2017). A study of 9- to 17-year-old boys found that testosterone levels peaked at 17 years of age (Khairullah & others, 2014).
The same influx of hormones that grows hair on a male’s chest and increases the fatty tissue in a female’s breasts may also contribute to psychological development in adolescence (Berenbaum, Beltz, & Corley, 2015; Wang & others, 2017). In one study of boys and girls ranging in age from 9 to 14, a higher concentration of testosterone was present in boys who rated themselves as more socially competent (Nottelmann & others, 1987). However, a research review concluded that there is insufficient quality research to confirm that changing testosterone levels during puberty are linked to mood and behavior in adolescent males (Duke, Balzer, & Steinbeck, 2014). And hormonal effects by themselves do not account for adolescent development (Susman & Dorn, 2013). For example, in one study, social factors were much better predictors of young adolescent girls’ depression and anger than hormonal factors (Brooks-Gunn & Warren, 1989). Behavior and moods also can affect hormones (DeRose & Brooks-Gunn, 2008). Stress, eating patterns, exercise, sexual activity, tension, and depression can activate or suppress various aspects of the hormonal system (Marceau, Dorn, & Susman, 2012). In sum, the hormone-behavior link is complex (Susman & Dorn, 2013).
Timing and Variations in Puberty In the United States—where children mature up to a year earlier than children in European countries—the average age of menarche has declined significantly since the mid-nineteenth century (see Figure 2). Also, recent studies in Korea and Japan (Cole & Mori, 2018), China (Song & others, 2017), and Saudi Arabia (Al Alwan & others, 2017) found that pubertal onset has been occurring earlier in recent years. Fortunately, however, we are unlikely to see pubescent toddlers, since what has happened in the past century is likely the result of improved nutrition and health.
FIGURE 2 AGE AT MENARCHE IN NORTHERN EUROPEAN COUNTRIES AND THE UNITED STATES IN THE NINETEENTH AND TWENTIETH CENTURIES. Notice the steep decline in the age at which girls experienced menarche in four northern European countries and the United States from 1845 to 1969. Recently the age at which girls experience menarche has been leveling off.
Why do the changes of puberty occur when they do, and how can variations in their timing be explained? The basic genetic program for puberty is wired into the species (Day & others, 2017; Kiess & others, 2016). Weight also is linked to pubertal onset. A cross-cultural study in 29 countries found that childhood obesity was linked to early puberty in girls (Currie & others, 2012). And a study of Chinese girls confirmed that childhood obesity contributed to an earlier onset of puberty (Zhai & others, 2015).
Experiences that are linked to earlier pubertal onset include nutrition, an urban environment, low socioeconomic status, adoption, father absence, family conflict, maternal harshness, child maltreatment, and early substance use (Bratke & others, 2017). For example, a recent study found that child sexual abuse was linked to earlier pubertal onset (Noll & others, 2017). In many cases, puberty comes months earlier in these situations, and this earlier onset of puberty is likely explained by high rates of conflict and stress in these social contexts.
What are some of the differences in the ways girls and boys experience pubertal growth?
©Fuse/Getty Images
For most boys, the pubertal sequence may begin as early as age 10 or as late as 13½, and it may end as early as age 13 or as late as 17. Thus, the normal range is wide enough that, given two boys of the same chronological age, one might complete the pubertal sequence before the other one has begun it. For girls, menarche is considered within the normal range if it appears between the ages of 9 and 15. An increasing number of U.S. girls are beginning puberty at 8 and 9 years of age, with African American girls developing earlier than non-Latino White girls (Herman-Giddens, 2007; Selkie, 2018; Sorensen & others, 2012).
Body Image One psychological aspect of physical Page 343change in puberty is universal: Adolescents are preoccupied with their bodies and develop images of what their bodies are like (Senin-Calderon & others, 2017; Solomon-Krakus & others, 2017). Preoccupation with body image is strong throughout adolescence but is especially acute during early adolescence, a time when adolescents are more dissatisfied with their bodies than in late adolescence.
The recent dramatic increase in Internet and social media use has raised concerns about their influence on adolescents’ body images. For example, a recent study of U.S. 12- to 14-year-olds found that heavier social media use was associated with body dissatisfaction (Burnette, Kwitowski, & Mazzeo, 2017). Also, in a recent study of U.S. college women, spending more time on Facebook was related to more frequent body and weight concern comparisons with other women, more attention to the physical appearance of others, and more negative feelings about their own bodies (Eckler, Kalyango, & Paasch, 2017), In sum, various aspects of exposure to the Internet and social media are increasing the body dissatisfaction of adolescents and emerging adults, especially females.
Gender differences characterize adolescents’ perceptions of their bodies (Hoffman & Warschburger, 2017; Mitchison & others, 2017). In general, girls are less happy with their bodies and have more negative body images than boys throughout puberty (Griffiths & others, 2017). In a recent U.S. study of young adolescents, boys had a more positive body image than girls (Morin & others, 2017). Girls’ more negative body images may be due to media portrayals of the attractiveness of being thin and the increase in body fat in girls during puberty (Benowitz-Fredericks & others, 2012). One study found that both boys’ and girls’ body images became more positive as they moved from the beginning to the end of adolescence (Holsen, Carlson Jones, & Skogbrott Birkeland, 2012).
Early and Late Maturation You may have entered puberty earlier or later than average, or perhaps you were right on schedule. Adolescents who mature earlier or later than their peers perceive themselves differently (Lee & others, 2017; Wang & others, 2018). In the Berkeley Longitudinal Study some years ago, early-maturing boys perceived themselves more positively and had more successful peer relations than did their late-maturing counterparts (Jones, 1965). When the late-maturing boys were in their thirties, however, they had developed a stronger sense of identity than the early-maturing boys had (Peskin, 1967). This identity development may have occurred because the late-maturing boys had more time to explore life’s options, or because the early-maturing boys continued to focus on their advantageous physical status instead of on career development and achievement. More recent research confirms, though, that at least during adolescence it is advantageous to be an early-maturing rather than a late-maturing boy (Graber, Brooks-Gunn, & Warren, 2006).
Early and late maturation have been linked with body image. In one study, in the sixth grade, early-maturing girls showed greater satisfaction with their figures than did late-maturing girls, but by the tenth grade late-maturing girls were more satisfied (Simmons & Blyth, 1987) (see Figure 3). A possible reason for this is that in late adolescence early-maturing girls are shorter and stockier, whereas late-maturing girls are taller and thinner. Thus, late-maturing girls in late adolescence have bodies that more closely approximate the current American ideal of feminine beauty—tall and thin. Also, one study found that in the early high school years, late-maturing boys had a more negative body image than early-maturing boys (de Guzman & Nishina, 2014).
FIGURE 3 EARLY- AND LATE-MATURING ADOLESCENT GIRLS’ PERCEPTIONS OF BODY IMAGE IN EARLY AND LATE ADOLESCENCE. The sixth-grade girls in this study had positive body image scores if they were early maturers but negative body image scores if they were late maturers (Simmons & Blyth, 1987). Positive body image scores indicated satisfaction with their figures. By the tenth grade, however, it was the late maturers who had positive body image scores.
An increasing number of researchers have found that early maturation increases girls’ vulnerability to a number of problems (Selkie, 2018). Early-maturing girls are more likely to smoke, drink, be depressed, have an eating disorder, engage in delinquency, struggle for earlier independence from their parents, and have older friends; and their bodies are likely to elicit responses from males that lead to earlier dating and earlier sexual experiences (Ibitoye & others, 2017; Pomerantz & others, 2017; Wang & others, 2018). In a recent study, onset of menarche before 11 years of age was linked to a higher incidence of distress disorders, fear disorders, and externalizing disorders in females (Platt & others, 2017). Another study found that early maturation predicted a stable higher level of depression for adolescent girls (Rudolph & others, 2014). Further, researchers recently found that early-maturing girls had higher rates of depression and antisocial behavior as middle-aged adults, mainly because their difficulties began in adolescence and did not lessen over time (Mendle & others, 2018). Further, early-maturing girls tend to have sexual intercourse earlier and to have more unstable sexual relationships, and they are more at risk for physical and verbal abuse in dating (Chen, Rothman, & Jaffee, 2017; Moore, Harden, & Mendle, 2014). And early-maturing girls are less likely to graduate from high Page 344school and tend to cohabit and marry earlier (Cavanagh, 2009). Apparently as a result of their social and cognitive immaturity, combined with early physical development, early-maturing girls are easily lured into problem behaviors, not recognizing the possible long-term negative effects on their development.
In sum, early maturation often has more favorable outcomes in adolescence for boys, especially in early adolescence. However, late maturation may be more favorable for boys, especially in terms of identity and career development. Research increasingly has found that early-maturing girls are vulnerable to a number of problems.
THE BRAIN
Along with the rest of the body, the brain changes during adolescence, but the study of adolescent brain development is still in its infancy. As advances in technology take place, significant strides are also likely to be made in charting developmental changes in the adolescent brain (Cohen & Casey, 2017; Crone, Peters, & Steinbeis, 2018; Sherman, Steinberg, & Chein, 2018; Steinberg & others, 2018; Vijayakumar & others, 2018). What do we know now?
The dogma of the unchanging brain has been discarded, and researchers are mainly focused on context-induced plasticity of the brain over time (Romeo, 2017; Steinberg, 2017; Zelazo, 2013). The development of the brain mainly changes in a bottom-up, top-down sequence with sensory, appetitive (eating, drinking), sexual, sensation-seeking, and risk-taking brain linkages maturing first and higher-level brain linkages such as self-control, planning, and reasoning maturing later (Zelazo, 2013).
Using fMRI brain scans, scientists have recently discovered that adolescents’ brains undergo significant structural changes (Aoki, Romeo, & Smith, 2017; Crone, Peters, & Steinbeis, 2018; Goddings & Mills, 2017; Rudolph & others, 2017). The corpus callosum, where fibers connect the brain’s left and right hemispheres, thickens in adolescence, and this improves adolescents’ ability to process information (Chavarria & others, 2014). We have described advances in the development of the prefrontal cortex—the highest level of the frontal lobes involved in reasoning, decision making, and self-control. However, the prefrontal cortex doesn’t finish maturing until the emerging adult years, approximately 18 to 25 years of age, or later (Cohen & Casey, 2017; Juraska & Willing, 2017; Sousa & others, 2018).
developmental connection
Brain Development
Although the prefrontal cortex shows considerable development in childhood, it is still not fully mature even in adolescence. Connect to “Physical and Cognitive Development in Middle and Late Childhood.”
At a lower, subcortical level, the limbic system, which is the seat of emotions and where rewards are experienced, matures much earlier than the prefrontal cortex and is almost completely developed in early adolescence (Mueller & others, 2017). The limbic system structure that is especially involved in emotion is the amygdala. Figure 4 shows the locations of the corpus callosum, prefrontal cortex, and the limbic system.
FIGURE 4 THE CHANGING ADOLESCENT BRAIN: PREFRONTAL CORTEX, LIMBIC SYSTEM, AND CORPUS CALLOSUM
With the onset of puberty, the levels of neurotransmitters change (Cohen & Casey, 2017). For example, an increase in the neurotransmitter dopamine occurs in both the prefrontal cortex and the limbic system during adolescence (Cohen & Casey, 2017). Increases in dopamine have been linked to increased risk taking and the use of addictive drugs (Webber & others, 2017). Researchers also have found that dopamine plays an important role in reward seeking during adolescence (Dubol & others, 2018).
Earlier we described the increased focal activation that is linked to synaptic pruning in a specific region, such as the prefrontal cortex. In middle and late childhood, while there is increased focal activation within a specific brain region such as the prefrontal cortex, there are limited connections across distant brain regions. As adolescents develop, they have more connections across brain areas (Lebel & Deoni, 2018; Quinlin & others, 2017; Sousa & others, 2018; Tashjian, Goldenberg, & Galvan, 2017). The increased connectedness (referred to as brain networks) is especially prevalent across more distant brain regions. Thus, as children develop, greater efficiency and focal activation occurs in close Page 345-by areas of the brain, and simultaneously there is an increase in brain networks connecting more distant brain regions. In a recent study, reduced connectivity between the brain’s frontal lobes and amygdala during adolescence was linked to increased depression (Scheuer & others, 2017).
Many of the changes in the adolescent brain that have been described here involve the rapidly emerging fields of developmental cognitive neuroscience and developmental social neuroscience, in which connections between development, the brain, and cognitive or socioemotional processes are studied (Lauharatanahirun & others, 2018; Mueller & others, 2017; Romer, Reyna, & Sattherthwaite, 2017; Sherman, Steinberg, & Chein, 2018; Steinberg & others, 2018). For example, consider leading researcher Charles Nelson’s (2003) view that, although adolescents are capable of very strong emotions, their prefrontal cortex hasn’t adequately developed to the point at which they can control these passions. It is as if their brain doesn’t have the brakes to slow down their emotions. Or consider this interpretation of the development of emotion and cognition in adolescents: “early activation of strong ‘turbo-charged’ feelings with a relatively unskilled set of ‘driving skills’ or cognitive abilities to modulate strong emotions and motivations” (Dahl, 2004, p. 18).
Of course, a major question is which comes first, biological changes in the brain or experiences that stimulate these changes (Lerner, Boyd, & Du, 2008; Steinberg, 2017). In a longitudinal study, 11- to 18-year-olds who lived in poverty conditions had diminished brain functioning at 25 years of age (Brody & others, 2017). However, the adolescents from poverty backgrounds whose families participated in a supportive parenting intervention did not show this diminished brain functioning in adulthood. Another study found that the prefrontal cortex thickened and more brain connections formed when adolescents resisted peer pressure (Paus & others, 2007). Scientists have yet to determine whether the brain changes come first or whether they result from experiences with peers, parents, and others (Lauharatanahirun & others, 2018; Webber & others, 2017). Once again, we encounter the nature-nurture issue that is so prominent in an examination of development through the life span. Nonetheless, there is adequate evidence that environmental experiences make important contributions to the brain’s development (Cohen & Casey, 2017; Crone, 2017; Sherman, Steinberg, & Chein, 2018).
In closing this section on the development of the brain in adolescence, a further caution is in order. Much of the research on neuroscience and the development of the brain in adolescence is correlational in nature, and thus causal statements need to be scrutinized (Steinberg & others, 2018). This caution, of course, applies to any period in the human life span.
ADOLESCENT SEXUALITY
Not only is adolescence characterized by substantial changes in physical growth and the development of the brain, but adolescence also is a bridge between the asexual child and the sexual adult (Diamond & Alley, 2018; Savin-Williams, 2017, 2018). Adolescence is a time of sexual exploration and experimentation, of sexual fantasies and realities, of incorporating sexuality into one’s identity. Adolescents have an almost insatiable curiosity about sexuality. They are concerned about whether they are sexually attractive, how to do sex, and what the future holds for their sexual lives. Although most adolescents experience times of vulnerability and confusion, the majority will eventually develop a mature sexual identity.
In the United States, the sexual culture is widely available to adolescents. In addition to any advice adolescents get from parents, they learn a great deal about sex from television, videos, magazines, the lyrics of popular music, and the Internet (Bleakley & others, 2017; Kinsler & others, 2018; van Oosten & Vandenbosch, 2017). In some schools, sexting is common, as indicated in a recent study of 656 high school students at one school in which 15.8 percent of males and 13.6 percent of females reported sending and 40.5 percent of males and 30.6 percent of females reported receiving explicit sexual pictures on cell phones (Strassberg, Cann, & Velarde, 2017). And in another recent study of 13- to 21-year-old Latinos, engaging in sexting was linked to engaging in penetrative sex (oral, vaginal, and anal sex) (Romo & others, 2017).
Sexual arousal emerges as a new phenomenon in adolescence and it is important to view sexuality as a normal aspect of adolescent development.
—Shirley Feldman
Contemporary Psychologist, Stanford University
Developing a Sexual Identity Mastering emerging sexual feelings and forming a sense of sexual identity are multifaceted and lengthy processes (Diamond & Alley, 2018; Savin-Williams, 2017, 2018). They involve learning to manage sexual feelings (such as sexual arousal and attraction), developing new forms of intimacy, and learning how to regulate sexual behavior to avoid undesirable consequences.
An adolescent’s sexual identity involves activities Page 346, interests, styles of behavior, and an indication of sexual orientation (whether an individual has same-sex or other-sex attractions, or both) (Goldberg & Halpern, 2017). For example, some adolescents have a high anxiety level about sex, others a low level. Some adolescents are strongly aroused sexually, others less so. Some adolescents are very active sexually, others not at all (Hyde & DeLamater, 2017). Some adolescents are sexually inactive in response to their strong religious upbringing; others go to church regularly and yet their religious training does not inhibit their sexual activity.
It is commonly thought that most gays and lesbians quietly struggle with same-sex attractions in childhood, do not engage in heterosexual dating, and gradually recognize that they are a gay or lesbian in mid- to late adolescence. Many youth do follow this developmental pathway, but others do not (Diamond & Alley, 2018; Savin-Williams, 2017, 2018). For example, many youth have no recollection of early same-sex attractions and experience a more abrupt sense of their same-sex attraction in late adolescence. The majority of adolescents with same-sex attractions also experience some degree of other-sex attractions (Carroll, 2018). Even though some adolescents who are attracted to individuals of their same sex fall in love with these individuals, others claim that their same-sex attractions are purely physical (Diamond & Alley, 2018; Savin-Williams, 2017, 2018).
Further, the majority of sexual minority (gay, lesbian, and bisexual) adolescents have competent and successful paths of development through adolescence and become healthy and productive adults. However, in a recent large-scale study, sexual minority adolescents did engage in a higher prevalence of health-risk behaviors (greater drug use and sexual risk taking, for example) compared with heterosexual adolescents (Kann & others, 2016b).
The Timing of Adolescent Sexual Behaviors What is the current profile of sexual activity of adolescents? In a U.S. national survey conducted in 2015, 58 percent of twelfth-graders reported having experienced sexual intercourse, compared with 24 percent of ninth-graders (Kann & others, 2016a). By age 20, 77 percent of U.S. youth report having engaged in sexual intercourse (Dworkin & Santelli, 2007). Nationally, 46 percent of twelfth-graders, 33.5 percent of eleventh-graders, 25.5 percent of tenth-graders, and 16 percent of ninth-graders recently reported that they were currently sexually active (Kann & others, 2016a).
developmental connection
Sexuality
What characterizes the sexual activity of emerging adults (18 to 25 years of age)? Connect to “Physical and Cognitive Development in Early Adulthood.”
What trends in adolescent sexual activity have occurred in recent decades? From 1991 to 2015, fewer adolescents reported any of the following: ever having had sexual intercourse, currently being sexually active, having had sexual intercourse before the age of 13, and having had sexual intercourse with four or more persons during their lifetime (Kann & others, 2016a) (see Figure 5).
FIGURE 5 SEXUAL ACTIVITY OF U.S. ADOLESCENTS FROM 1991 TO 2015
Sexual initiation varies by ethnic group in the United States (Kann & others, 2016a). African Americans are likely to engage in sexual behaviors earlier than other ethnic groups, whereas Asian Americans are likely to engage in them later (Feldman, Turner, & Araujo, 1999). In a more recent national U.S. survey of ninth- to twelfth-graders, 48.5 percent of African Americans, 42.5 percent of Latinos, and 39.9 percent of non-Latino Whites said they had experienced sexual intercourse (Kann & others, 2016a). In this study, 8 percent of African Americans (compared with 5 percent of Latinos and 2.5 percent of non-Latino Whites) said they had their first sexual experience before 13 years of age.
Research indicates that oral sex is now a common occurrence among U.S. adolescents (Fava & Bay-Cheng, 2012; Song & Halpern-Felsher, 2010). In a national survey, 51 percent of U.S. 15- to 19-year-old boys and 47 percent of girls in the same age range said they had engaged in oral sex (Child Trends, 2015). Researchers have also found that among female adolescents who reported having vaginal sex first, 31 percent reported having a teen pregnancy, whereas among those who initiated oral-genital sex first, only 8 percent reported having a teen pregnancy (Reese & others, 2013). Thus, how adolescents initiate their sex lives may have positive or negative consequences for their sexual health.
Risk Factors in Adolescent Sexual Behavior Many adolescents are not emotionally prepared to handle sexual experiences, especially in early adolescence (Cai & others, 2018; Donenberg & others, 2018; Ihongbe, Cha, & Masho, 2017). Early sexual activity is linked with risky behaviors Page 347such as drug use, delinquency, and school-related problems (Boisvert, Boislard, & Poulin, 2017; Rivera & others, 2018). A recent study of more than 3,000 Swedish adolescents revealed that sexual intercourse before age 14 was linked to risky behaviors such as an increased number of sexual partners, experience of oral and anal sex, negative health behaviors (smoking, drug and alcohol use), and antisocial behavior (being violent, stealing, running away from home) at 18 years of age (Kastbom & others, 2016). Further, a recent study found that early sexual debut (first sexual intercourse before age 13) was associated with sexual risk taking, substance use, violent victimization, and suicidal thoughts/attempts in both sexual minority (in this study, gay, lesbian, and bisexual adolescents) and heterosexual youth (Lowry, Robin, & Kann, 2017). And in a recent study of Korean adolescent girls, early menarche was linked with earlier initiation of sexual intercourse (Kim & others, 2018).
In addition to having sex in early adolescence, other risk factors for sexual problems in adolescence include contextual factors such as socioeconomic status (SES) and poverty, immigration/ethnic minority status, family/parenting and peer factors, and school-related influences (Simons & others, 2016; Warner, 2018). The percentage of sexually active young adolescents is higher in low-income areas of inner cities (Morrison-Beedy & others, 2013). One study revealed that neighborhood poverty concentrations predicted 15- to 17-year-old girls’ and boys’ sexual initiation (Cubbin & others, 2010). Also, a national survey of 15- to 20-year-olds found that Spanish-speaking immigrant youth were more likely to have a sexual partner age difference of 6 or more years and less likely to use contraception at first sexual intercourse than their native Latino, non-Latino White, and English-speaking Latino immigrant counterparts (Haderxhanaj & others, 2014).
What are some risks associated with early initiation of sexual intercourse?
©Stockbyte/PunchStock
A number of family factors are associated with sexual risk-taking (Ashcraft & Murray, 2017; Ruiz-Casares & others, 2017). For example, a recent study revealed that adolescents who in the eighth grade reported greater parental knowledge and more family rules about dating were less likely to initiate sex from the eighth to tenth grade (Ethier & others, 2016). Also, a recent study revealed that of a number of parenting practices the factor that best predicted a lower level of risky sexual behavior by adolescents was supportive parenting (Simons & others, 2016). Further, one study found that difficulties and disagreements between Latino adolescents and their parents were linked to the adolescents’ early sex initiation (Cordova & others, 2014). Also, having older sexually active siblings or pregnant/parenting teenage sisters placed adolescent girls at higher risk for pregnancy (Miller, Benson, & Galbraith, 2001).
Peer, school, sport, and religious contexts provide further information about sexual risk taking in adolescents (Choukas-Bradley & Prinstein, 2016). One study found that adolescents who associated with more deviant peers in early adolescence were likely to have more sexual partners at age 16 (Lansford & others, 2010). Also, a research review found that school connectedness was linked to positive sexuality outcomes (Markham & others, 2010). A study of middle school students revealed that better academic achievement was a protective factor in preventing boys and girls from engaging in early sexual intercourse (Laflin, Wang, & Barry, 2008). Also, a recent study found that adolescent males who play sports engage in a higher level of sexual risk taking, while adolescent females who play sports engage in a lower level of sexual risk taking (Lipowski & others, 2016). And a recent study of African American adolescent girls indicated that those who reported that religion was of low or moderate importance to them had a much earlier sexual debut that their counterparts who said that religion was very important or extremely important to them (George Dalmida & others, 2018).
Psychologists are exploring ways to encourage adolescents to make less risky sexual decisions. Here an adolescent participates in an interactive video session developed by Julie Downs and her colleagues at the Department of Social and Decision Making Sciences at Carnegie Mellon University. The videos help adolescents evaluate their responses and decisions in high-risk sexual contexts.
©Michael Ray
Cognitive and personality factors are increasingly implicated in sexual risk taking in adolescence. Weak self-regulation (difficulty controlling one’s emotions and behavior) and impulsiveness are two such factors. Another longitudinal study found that weak self-regulation at 8 to 9 years of age and risk proneness (tendency to seek sensation Page 348and make poor decisions) at 12 to 13 years of age set the stage for sexual risk taking at 16 to 17 years of age (Crockett, Raffaelli, & Shen, 2006). Also, a meta-analysis indicated that the link between impulsivity and risky sexual behavior was likely to be more characteristic of adolescent females than males (Dir, Coskunpinar, & Cyders, 2014).
Contraceptive Use Too many sexually active adolescents still do not use contraceptives, use them inconsistently, or use contraceptive methods that are less effective than others (Chandra-Mouli & others, 2018; Diedrich, Klein, & Peipert, 2017; Fridy & others, 2018; Jaramillo & others, 2017). In 2015, 14 percent of sexually active adolescents did not use any contraceptive method the last time they had sexual intercourse (Kann & others, 2016a). Researchers have found that U.S. adolescents are less likely to use condoms than their European counterparts (Jorgensen & others, 2015).
developmental connection
Conditions, Diseases, and Disorders
What are some good strategies for protecting against HIV and other sexually transmitted infections? Connect to “Physical and Cognitive Development in Early Adulthood.”
Recently, a number of leading medical organizations and experts have recommended that adolescents use long-acting reversible contraception (LARC). These include the Society for Adolescent Health and Medicine (2017), the American Academy of Pediatrics and American College of Obstetrics and Gynecology (Allen & Barlow, 2017), and the World Health Organization (2017). LARC consists of the use of intrauterine devices (IUDs) and contraceptive implants, which have a much lower failure rate and are more effective in preventing unwanted pregnancy than birth control pills and condoms (Diedrich, Klein, & Peipert, 2017; Fridy & others, 2018; Society for Adolescent Health and Medicine, 2017).
Sexually Transmitted Infections Some forms of contraception, such as birth control pills or implants, do not protect against sexually transmitted infections, or STIs. Sexually transmitted infections (STIs) are contracted primarily through sexual contact, including oral-genital and anal-genital contact. Every year more than 3 million American adolescents (about one-fourth of those who are sexually experienced) acquire an STI (Centers for Disease Control and Prevention, 2018). In a single act of unprotected sex with an infected partner, a teenage girl has a 1 percent risk of getting HIV, a 30 percent risk of acquiring genital herpes, and a 50 percent chance of contracting gonorrhea (Glei, 1999). Yet another very widespread STI is chlamydia. We will consider these and other sexually transmitted infections in more detail later.
Adolescent Pregnancy Adolescent pregnancy is another problematic outcome of sexuality in adolescence and requires major efforts to reduce its occurrence (Brindis, 2017; Chandra-Mouli & others, 2018; Fridy & others, 2018; Marseille & others, 2018; Romero & others, 2017; Tevendale & others, 2017). In cross-cultural comparisons, the United States continues to have one of the highest adolescent pregnancy and childbearing rates in the industrialized world, despite a considerable decline during the 1990s. The U.S. adolescent pregnancy rate is eight times as high as that in the Netherlands. Although U.S. adolescents are no more sexually active than their counterparts in the Netherlands, their adolescent pregnancy rate is dramatically higher. In the United States, 82 percent of pregnancies in adolescents 15 to 19 years of age are unintended (Koh, 2014). A cross-cultural comparison found that among 21 countries, the United States had the highest adolescent pregnancy rate among 15- to 19-year-olds and Switzerland the lowest (Sedgh & others, 2015).
Despite the negative comparisons of the United States with many other developed countries, there have been some encouraging trends in U.S. adolescent pregnancy rates. In 2015, the U.S. birth rate for 15- to 19-year-olds was 22.3 births per 1,000 females, the lowest rate ever recorded, which represents a dramatic decrease from the 61.8 births for the same age range in 1991 and down even 8 percent from 2014 (Martin & others, 2017) (see Figure 6). There also has been a substantial decrease in adolescent pregnancies across ethnic groups in recent years. Reasons for the decline include school/community health classes, increased contraceptive Page 349use, and fear of sexually transmitted infections such as AIDS.
FIGURE 6 BIRTH RATES FOR U.S. 15- TO 19-YEAR-OLD GIRLS FROM 1980 TO 2015.
Source: Martin, J. A. et al. “Births: Final data for 2015.” National Vital Statistics Reports, 66 (1), 2017, 1.
Ethnic variations characterize birth rates for U.S. adolescents. Latina adolescents are more likely than African American and non-Latina White adolescents to have a child (Martin & others, 2017). Latina and African American adolescent girls who have a child are also more likely to have a second child than are non-Latina White adolescent girls (Rosengard, 2009). And daughters of teenage mothers are at increased risk for teenage childbearing, thus perpetuating an intergenerational cycle (Meade, Kershaw, & Ickovics, 2008).
Adolescent pregnancy creates health risks for both the baby and the mother (Leftwich & Alves, 2017). Infants born to adolescent mothers are more likely to have low birth weights—a prominent factor in infant mortality—as well as neurological problems and childhood illness (Leftwich & Alves, 2017). A recent study assessed the reading and math achievement trajectories of children born to adolescent and non-adolescent mothers with different levels of education (Tang & others, 2016). In this study, higher levels of maternal education were linked to higher academic achievement through the eighth grade. Nonetheless, the achievement of children born to adolescent mothers never reached the levels of children born to adult mothers. Adolescent mothers are more likely to be depressed and to drop out of school than their peers are (Siegel & Brandon, 2014). Although many adolescent mothers resume their education later in life, they generally never catch up economically with women who postpone childbearing until their twenties. Also, a study of African American urban youth found that at 32 years of age, women who had become mothers as teenagers were more likely than non-teen mothers to be unemployed, live in poverty, depend on welfare, and not have completed college (Assini-Meytin & Green, 2015). In this study, at 32 years of age, men who had become fathers as teenagers were more likely than non-teen fathers to be unemployed.
A special concern is repeated adolescent pregnancy. In a recent national study, the percentage of teen births that were repeat births decreased from 2004 (21 percent) to 2015 (17 percent) (Dee & others, 2017). In a recent meta-analysis, use of effective contraception, especially LARC, and education-related factors (higher level of education and school continuation) resulted in a lower incidence of repeated teen pregnancy, while depression and a history of abortion were linked to a higher percentage of repeated teen pregnancy (Maravilla & others, 2017).
Researchers have found that adolescent mothers interact less effectively with their infants than do adult mothers (Leftwich & Alves, 2017). One study revealed that adolescent mothers spent more time negatively interacting and less time in play and positive interactions with their infants than did adult mothers (Riva Crugnola & others, 2014). Also, a recent intervention, “My Baby and Me,” that involved frequent, intensive home visitation coaching sessions with adolescent mothers across three years resulted in improved maternal behavior and child outcomes (Guttentag & others, 2014).
Although the consequences of America’s high rate of adolescent pregnancy are cause for great concern, it often is not pregnancy alone that leads to negative consequences for an adolescent mother and her offspring. Adolescent mothers are more likely to come from low-SES backgrounds (Mollborn, 2017). Many adolescent mothers also were not good students before they became pregnant (Malamitsi-Puchner & Boutsikou, 2006). However, not every adolescent female who bears a child lives a life of poverty and low achievement. Thus, although adolescent pregnancy is a high-risk circumstance, and adolescents who do not become pregnant generally fare better than those who do, some adolescent mothers do well in school and have positive outcomes (Schaffer & others, 2012).
Serious, extensive efforts are needed to help pregnant adolescents and young mothers enhance their educational and occupational opportunities (Carroll, 2018; Craft, Brandt, & Prince, 2016; Mueller & others, 2017; Romero & others, 2017). Adolescent mothers also need help obtaining competent child care and planning for the future.
Adolescents can benefit from age-appropriate family-life education (Barfield, Warner, & Kappeler, 2017; Mueller & others, 2017). Family and consumer science educators teach life skills, such as effective decision making, to adolescents. To read about the work of one family and consumer science educator, see Connecting with Careers. And to learn more about ways to reduce adolescent pregnancy, see Connecting Development to Life.
What are some consequences of adolescent pregnancy?
©Geoff Manasse/Getty ImagesPage 350
connecting with careers
Lynn Blankinship, Family and Consumer Science Educator
Lynn Blankinship is a family and consumer science educator with an undergraduate degree in this field from the University of Arizona. She has taught for more than 20 years, the last 14 at Tucson High Magnet School.
Blankinship has been honored as the Tucson Federation of Teachers Educator of the Year and the Arizona Teacher of the Year. Blankinship especially enjoys teaching life skills to adolescents. One of her favorite activities is having students care for an automated baby that imitates the needs of real babies. She says that this program has a profound impact on students because the baby must be cared for around the clock for the duration of the assignment. Blankinship also coordinates real-world work experiences and training for students in several child-care facilities in the Tucson area.
For more information about what family and consumer science educators do, see the Careers in Life-Span Development appendix.
Lynn Blankinship (center) teaches life skills to students.
Courtesy of Lynn Blankinship
connecting development to life
Reducing Adolescent Pregnancy
One strategy for reducing adolescent pregnancy, called the Teen Outreach Program (TOP), focuses on engaging adolescents in volunteer community service and stimulates discussions that help adolescents appreciate the lessons they learn through volunteerism.
Girls Inc. has four programs that are intended to increase adolescent girls’ motivation to avoid pregnancy until they are mature enough to make responsible decisions about motherhood (Roth & others, 1998). Growing Together, a series of five two-hour workshops for mothers and adolescents, and Will Power/Won’t Power, a series of six two-hour sessions that focus on assertiveness training, are for 12- to 14-year-old girls. For older adolescent girls, Taking Care of Business provides nine sessions that emphasize career planning as well as information about sexuality, reproduction, and contraception. Health Bridge coordinates health and education services—girls can participate in this program as one of their club activities. Girls who participated in these programs were less likely to get pregnant than girls who did not participate (Girls Inc., 1991).
In 2010, the U.S. government launched the Teen Pregnancy Prevention (TPP) program under the direction of the newly created Office of Adolescent Health (Koh, 2014). Currently, a number of studies are being funded by the program in an effort to find ways to reduce the rate of adolescent pregnancy.
The sources and the accuracy of adolescents’ sexual information are linked to adolescent pregnancy. Adolescents can get information about sex from many sources, including parents, siblings, schools, peers, magazines, television, and the Internet. A special concern is the accuracy of sexual information to which adolescents have access on the Internet.
Currently, a major controversy in sex education is whether schools should have an abstinence-only program or a program that emphasizes contraceptive knowledge (Erkut & others, 2013; MacKenzie, Hedge, & Enslin, 2017). Recent research reviews have concluded that abstinence-only programs do not delay the initiation of sexual intercourse and do not reduce HIV risk behaviors (Denford & others, 2017; Jaramillo & others, 2017; Santelli & others, 2017).
Despite the evidence that favors comprehensive sex education, there recently has been an increase in government funding for abstinence-only programs (Donovan, 2017). Also, in some states (Texas and Mississippi, for example), many students still either get abstinence-only or no sex education at all (Campbell, 2016; Pollock, 2017).
Recently, there also has been an increased emphasis in abstinence-only-until-marriage (AOUM) policies and programs. However, a major problem with such policies and programs is that a very large majority of individuals engage in sexual intercourse at some point in adolescence or emerging adulthood while the age of marriage continues to go up (27 for females, 29 for males in the United States) (Society for Adolescent Medicine, 2017).
Based on the information you read earlier about risk factors in adolescent sexual behavior, which segments of the adolescent population would benefit most from the types of sex education programs described here?
Page 351
Review Connect Reflect
LG2 Describe the changes involved in puberty, as well as changes in the brain and sexuality during adolescence.
Review
- What are some key aspects of puberty?
- What changes typically occur in the brain during adolescence?
- What are some important aspects of sexuality in adolescence?
Connect
- How might adolescent brain development be linked to adolescents’ decisions to engage in sexual activity or to abstain from it?
Reflect Your Own Personal Journey of Life
- Did you experience puberty earlier or later than your peers? How did this timing affect your development?
3 Issues in Adolescent Health
LG3 Identify adolescent problems related to health, substance use and abuse, and eating disorders.
Adolescent Health
Substance Use and Abuse
Eating Disorders
Many health experts argue that whether adolescents are healthy depends primarily on their own behavior. To improve adolescent health, adults should aim to (1) increase adolescents’ health-enhancing behaviors, such as eating nutritious foods, exercising, wearing seat belts, and getting adequate sleep; and (2) reduce adolescents’ health-compromising behaviors, such as drug abuse, violence, unprotected sexual intercourse, and dangerous driving.
ADOLESCENT HEALTH
Adolescence is a critical juncture in the adoption of behaviors that are relevant to health (Coore Desai, Reece, & Shakespeare-Pellington, 2017; Devenish, Hooley, & Mellor, 2017; Oldfield & others, 2018; Yap & others, 2017). Many of the behaviors that are linked to poor health habits and early death in adults begin during adolescence (Blake, 2017; Donatelle & Ketcham, 2018). Conversely, the early formation of healthy behavior patterns, such as regular exercise and a preference for foods low in fat and cholesterol, not only has immediate health benefits but helps in adulthood to delay or prevent disability and mortality from heart disease, stroke, diabetes, and cancer (Hales, 2018; Powers & Dodd, 2017).
Nutrition and Exercise Concerns are growing about adolescents’ nutrition and exercise habits (Donatelle, 2019; Powers & Dodd, 2017; Schiff, 2017, 2019; Smith & Collene, 2019). National data indicated that the percentage of overweight U.S. 12- to 19-year-olds increased from 11 percent in the early 1990s to nearly 20.5 percent in 2014 (Centers for Disease Control and Prevention, 2016). In another study, 12.4 percent of U.S. kindergarten children were obese, but by 14 years of age, 20.8 percent were obese (Cunningham, Kramer, & Narayan, 2014).
A special concern in American culture is the amount of fat we consume. Many of today’s adolescents virtually live on fast-food meals, which are high in fat. A comparison of adolescents in 28 countries found that U.S. and British adolescents were more likely to eat fried food and less likely to eat fruits and vegetables than adolescents in most other countries that were studied (World Health Organization, 2000). The National Youth Risk Survey found that U.S. high school students showed a linear decrease in their intake of fruits and vegetables from 1999 through 2015 (Kann & others, 2016a).
Being obese in adolescence predicts obesity in emerging adulthood. For example, a longitudinal study of more than 8,000 adolescents found that obese adolescents were more likely to develop severe obesity in emerging adulthood than were overweight or normal-weight adolescents (The & others, 2010). In another longitudinal study, the percentage of overweight individuals increased from 20 percent at 14 years of age to 33 percent at 24 years of age (Patton & others, 2011).
©Shutterstock/Thirteen
Researchers have found that individuals become Page 352less active as they reach and progress through adolescence (Alberga & others, 2012). A national study of U.S. adolescents revealed that physical activity increased until 13 years of age in boys and girls but then declined through 18 years of age (Kahn & others, 2008). A recent national study also found that adolescent girls were much less likely to have engaged in 60 minutes or more of vigorous exercise per day in 5 of the last 7 days (61 percent) than were boys (42 percent) (YRBSS, 2016). Ethnic differences in exercise participation rates of U.S. adolescents also occur, and these rates vary by gender. In the national study just mentioned, non-Latino White boys exercised the most, African American and Latino girls the least (YRBSS, 2016).
Positive physical outcomes of exercise in adolescence include a lower rate of obesity, reduced triglyceride levels, lower blood pressure, and a lower incidence of type II diabetes (Barton & others, 2017; Powers & Howley, 2018; Son & others, 2017; Walton-Fisette & Wuest, 2018; Xie & others, 2017). Also, one study found that adolescents who were high in physical fitness had better connectivity between brain regions than adolescents who were low in physical fitness (Herting & others, 2014). Exercise in adolescence also is linked to other positive outcomes. Higher levels of exercise are related to fewer depressive symptoms in adolescents (Gosmann & others, 2015). In a recent study, a high-intensity exercise program reduced depressive symptoms and improved the moods of depressed adolescents (Carter & others, 2016). In another study, young adolescents who exercised regularly had higher academic achievement (Hashim, Freddy, & Rosmatunisah, 2012). And in a recent research review, among a number of cognitive factors, memory was the factor that most often was improved by exercise in adolescence (Li & others, 2017).
What are some characteristics of adolescents’ exercise patterns?
©Tom Stewart/Corbis/Getty Images
Adolescents’ exercise is increasingly being found to be associated with parenting and peer relationships (Mason & others, 2017; Michaud & others, 2017). One study revealed that family meals during adolescence protected against becoming overweight or obese in adulthood (Berge & others, 2015). Another study revealed that female adolescents’ physical activity was linked to their male and female friends’ physical activity, while male adolescents’ physical activity was associated with their female friends’ physical activity (Sirard & others, 2013).
Researchers have found that screen time is associated with a number of adolescent health problems, including a lower rate of exercise and a higher rate of sedentary behavior (Pearson & others, 2017). In one research review, a higher level of screen-based sedentary behavior was associated with being overweight, having sleep problems, being depressed, and having lower levels of physical activity/fitness and psychological well-being (higher stress levels, for example (Costigan & others, 2013).
What types of interventions and activities have been successful in reducing overweight in adolescents and emerging adults? Research indicates that dietary changes and regular exercise are key components of weight reduction in adolescence and emerging adulthood (Fukerson & others, 2018; Lipsky & others, 2017; Martin & others, 2018; Powers & Howley, 2018). For example, a recent study found that a combination of regular exercise and a diet plan resulted in weight loss and enhanced executive function in adolescents (Xie & others, 2017).
Sleep Like nutrition and exercise, sleep is an important influence on well-being. Might changing sleep patterns in adolescence contribute to adolescents’ health-compromising behaviors? Recently there has been a surge of interest in adolescent sleep patterns (Hoyt & others, 2018; Meltzer, 2017; Palmer & others, 2018; Reddy & others, 2017; Seo & others, 2017; Wheaton & others, 2018). A longitudinal study in which adolescents completed a 24-hour diary every 14 days in ninth, tenth, and twelfth grades found that regardless of how much students studied each day, when the students sacrificed sleep time to study more than usual they had difficulty understanding what was taught in class and were more likely to struggle with class assignments the next day (Gillen-O’Neel, Huynh, & Fuligni, 2013). Also, a recent experimental study indicated that when adolescents’ sleep was restricted to five hours for five nights, then returned to ten hours for two nights, their sustained attention was negatively affected (especially in the early morning) and did not return to baseline levels during recovery (Agostini & others, 2017). Further, researchers have found that adolescents who get less than 7.7 hours of sleep per night on average have more emotional and peer-related problems, higher anxiety, and a higher level of suicidal ideation (Sarchiapone & others, 2014). And a recent national study of more than 10,000 13- to 18-year-olds revealed that later weeknight bedtime, shorter weekend bedtime delay, and both short and long periods of weekend oversleep were linked to increased rates of anxiety, mood, substance abuse, and behavioral disorders (Zhang & others, 2017). Further, in a four-year longitudinal study beginning at 12 years of age, poor sleep patterns (for example, shorter sleep duration and greater daytime sleepiness) at age 12 was associated with an increased likelihood Page 353of drinking alcohol and using marijuana at 16 years of age (Miller, Janssen, & Jackson, 2017). Also, recent Swedish studies revealed that adolescents with a shorter sleep duration were more likely to have more school absences, while shorter sleep duration and greater sleep deficits were linked to having a lower grade point average (Hysing & others, 2015, 2016).
In a recent national survey of youth, only 27 percent of U.S. adolescents got eight or more hours of sleep on an average school night (Kann & others, 2016a). In this study, the percentage of adolescents getting this much sleep on an average school night decreased as they got older (see Figure 7). Also, in other research with more than 270,000 U.S. adolescents from 1991–2012, adolescents were getting less sleep in recent years than in the past (Keyes & others, 2015).
FIGURE 7 DEVELOPMENTAL CHANGES IN U.S. ADOLESCENTS’ SLEEP PATTERNS ON AN AVERAGE SCHOOL NIGHT
The National Sleep Foundation (2006) conducted a U.S. survey of adolescent sleep patterns. Those who got inadequate sleep (eight hours or less) on school nights were more likely to feel tired or sleepy, to be cranky and irritable, to fall asleep in school, to be in a depressed mood, and to drink caffeinated beverages than their counterparts who got optimal sleep (nine or more hours). Also, a longitudinal study of more than 6,000 adolescents found that sleep problems were linked to subsequent suicidal thoughts and attempts in adolescence and early adulthood (Wong & Brower, 2012). Further, one study found that adolescents who got less than 7.7 hours of sleep per night on average had more emotional and peer-related problems, higher anxiety, and a higher level of suicidal ideation than their peers who got 7.7 hours of sleep or more (Sarchiapone & others, 2014).
Why are adolescents getting too little sleep? Among the reasons given are those involving electronic media, caffeine, and changes in the brain coupled with early school start times (Bartel, Scheeren, & Gradisar, 2018; Owens, 2014). In one study, adolescents averaged engaging in four electronic activities (in some cases, this involved simultaneous use of different devices) after 9 p.m. (Calamaro, Mason, & Ratcliffe, 2009). Engaging in these electronic activities in the evening can replace sleep time, and such media use may increase sleep-disrupting arousal (Cain & Gradisar, 2010). Also, a study of fourth- and seventh-graders found that sleeping near small screens (smartphones, for example), sleeping with a TV in the room, and more screen time were associated with shorter sleep duration in both children and adolescents (Falbe & others, 2015).
Caffeine intake by adolescents appears to be related to inadequate sleep (Owens, 2014). Greater caffeine intake as early as 12 years of age is linked to later sleep onset, shorter sleep duration, and increased daytime sleepiness (Carskadon & Tarokh, 2014). Further, researchers have yet to study the connection between adolescent sleep patterns and high levels of caffeine intake from energy drinks.
Mary Carskadon and her colleagues (2004, 2005, 2011a, b; Crowley & Carskadon, 2010; Tarokh & Carskadon, 2010) have conducted a number of research studies on adolescent sleep patterns. They found that when given the opportunity, adolescents will sleep an average of 9 hours and 25 minutes a night. Most get considerably less than nine hours of sleep, however, especially during the week. This shortfall creates a sleep deficit, which adolescents often attempt to make up on the weekend. The researchers also found that older adolescents tend to be sleepier during the day than younger adolescents. They theorized that this sleepiness was not due to academic work or social pressures. Rather, their research suggests that adolescents’ biological clocks undergo a shift as they get older, delaying their period of sleepiness by about one hour. A delay in the nightly release of the sleep-inducing hormone melatonin, which is produced in the brain’s pineal gland, seems to underlie this shift. Melatonin is secreted at about 9:30 p.m. in younger adolescents and approximately an hour later in older adolescents.
Carskadon concludes that early school starting times may cause grogginess, inattention in class, and poor performance on tests. Based on her research, school officials in Edina, Minnesota, decided to start classes at 8:30 a.m. rather than the usual 7:25 a.m. Since then there have been fewer referrals for discipline problems, and the number of students who report being ill or depressed has decreased. The school system reports that test scores have improved for high school students but not for middle school students. This finding supports Carskadon’s suspicion that early start times are likely to be more stressful for older than for younger adolescents.
In Mary Carskadon’s sleep laboratory at Brown University, an adolescent girl’s brain activity is being monitored. Carskadon (2005) says that in the morning, sleep-deprived adolescents’ “brains are telling them it’s night time . . . and the rest of the world is saying it’s time to go to school” (p. 19).
©Jim LoScalzo
One study found that just a 30-minute delay in school start time was linked to improvements in adolescents’ sleep, alertness, mood, and health (Owens, Belon, & Moss, 2010). In another study, early school start times were linked to a higher vehicle crash rate in adolescent Page 354drivers (Vorona & others, 2014). The American Academy of Pediatrics recommends that schools institute start times from 8:30 to 9:30 a.m. to improve adolescents’ academic performance and quality of life (Adolescent Sleep Working Group, AAP, 2014).
Do sleep patterns change in emerging adulthood? Research indicates that they do (Galambos, Howard, & Maggs, 2011). One study revealed that more than 60 percent of college students were categorized as poor-quality sleepers (Lund & others, 2010). In this study, the weekday bedtimes and rise times of first-year college students were approximately 1 hour and 15 minutes later than those of seniors in high school (Lund & others, 2010). However, the first-year college students had later bedtimes and rise times than third- and fourth-year college students, indicating that at about 20 to 22 years of age, a reverse in the timing of bedtimes and rise times occurs. In another study, consistently low sleep duration in college students was associated with less effective attention the next day (Whiting & Murdock, 2016). Also, in a recent study of college students, a higher level of text messaging (greater number of daily texts, awareness of nighttime cell phone notifications, and compulsion to check nighttime notifications) was linked to a lower level of sleep quality (Murdock, Horissian, & Crichlow-Ball, 2017).
Leading Causes of Death in Adolescence The three leading causes of death in adolescence are unintentional injuries, homicide, and suicide (National Center for Health Statistics, 2018). Almost half of all deaths from 15 to 24 years of age are due to unintentional injuries, the majority of them involving motor vehicle accidents. Risky driving habits, such as speeding, tailgating, and driving under the influence of alcohol or other drugs, may be more important contributors to these accidents than lack of driving experience (White & others, 2018; Williams & others, 2018). In about 50 percent of motor vehicle fatalities involving adolescents, the driver has a blood alcohol level of 0.10 percent—twice the level at which a driver is designated as “under the influence” in some states. Of growing concern is the increasingly common practice of mixing alcohol and energy drinks, which is linked to a higher rate of driving while intoxicated (Wilson & others, 2018). A high rate of intoxication is also found in adolescents who die as pedestrians or while using vehicles other than automobiles.
Homicide is the second leading cause of death in adolescence, especially among African American males (National Center for Health Statistics, 2018). Also notable is the adolescent suicide rate, which has tripled since the 1950s. Suicide accounts for 6 percent of deaths in the 10-to-14 age group and 12 percent of deaths in the 15-to-19 age group. We will discuss suicide in more detail later.
SUBSTANCE USE AND ABUSE
Each year since 1975, Lloyd Johnston and his colleagues at the Institute of Social Research at the University of Michigan have monitored the drug use of America’s high school seniors in a wide range of public and private high schools. Since 1991, they also have surveyed drug use by eighth- and tenth-graders. In 2017, the study surveyed approximately 45,000 secondary school students in 380 public and private schools (Johnston & others, 2018).
In the University of Michigan study, drug use among U.S. secondary school students declined in the 1980s but began to increase in the early 1990s before declining again in the early part of the first decade of the 21st century. However, from 2006 through 2017, overall use of illicit drugs began increasing again, due mainly to an increase in marijuana use by adolescents. In 2006, 36.5 percent of twelfth-graders reported annual use of an illicit drug but in 2017 that figure had increased to 39.9 percent. However, if marijuana use is subtracted from the annual use figures, there has been a significant decline in drug use by adolescents. When marijuana use is deleted, in 2006, 19.2 percent of twelfth-graders used an illicit drug annually, but that figure showed a significant decline to 13.3 percent in 2017 (Johnston & others, 2018). Marijuana is the most widely used illicit drug by adolescents.
The United States continues to have one of the highest rates of adolescent drug use of any industrialized nation. Because of the increased legalization of marijuana use for adults in a number of states, youth are likely to have increased access to the drug and it is expected that marijuana use by adolescents will increase in the future.
developmental connection
Substance Abuse
Does substance abuse increase or decrease in emerging adulthood? Connect to “Physical and Cognitive Development in Early Adulthood.”
Alcohol How extensive is alcohol use by U.S. adolescents? Sizable declines in adolescent alcohol use have occurred in recent years (Johnston & others, 2018). The percentage of U.S. eighth-graders who reported having had any alcohol to drink Page 355in the past 30 days fell from a 1996 high of 26 percent to 8.0 percent in 2017. The 30-day prevalence fell among tenth-graders from 39 percent in 2001 to 19.7 percent in 2017 and among high school seniors from 72 percent in 1980 to 33.2 percent in 2017. Binge drinking (defined in the University of Michigan surveys as having five or more drinks in a row in the last two weeks) by high school seniors declined from 41 percent in 1980 to 19.1 percent in 2015. Binge drinking by eighth- and tenth-graders also has dropped significantly in recent years. A consistent gender difference occurs in binge drinking, with males engaging in this behavior more than females do (Johnston & others, 2018).
A special concern is adolescents who drive while they are under the influence of alcohol or other substances (White & others, 2018; Williams & others, 2018; Wilson & others, 2018). In the University of Michigan Monitoring the Future Study, 30 percent of high school seniors said they had been in a vehicle with a drugged or drinking driver in the past two weeks (Johnston & others, 2008). And in a national study, one in four twelfth-graders reported that they had consumed alcohol mixed with energy drinks in the last 12 months, and this combination was linked to their unsafe driving (Martz, Patrick, & Schulenberg, 2015).
What are some trends in alcohol use by U.S. adolescents?
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Smoking Cigarette smoking (in which the active drug is nicotine) has been one of the most serious yet preventable health problems among adolescents and emerging adults (McKelvey & Halpern-Felsher, 2017). Cigarette smoking among U.S. adolescents peaked in 1996 and has declined significantly since then (Johnston & others, 2018). Following peak use in 1996, smoking rates for U.S. eighth-graders have fallen by 50 percent. In 2017, the percentage of twelfth-graders who reported having smoked cigarettes in the last 30 days was 9.7 percent, an 8 percent decrease from 2011, while the rate for tenth-graders was 5.0 percent and the rate for eighth-graders was 1.9 percent. Since the mid-1990s an increasing percentage of adolescents have reported that they perceive cigarette smoking as dangerous, that they disapprove of it, that they are less accepting of being around smokers, and that they prefer to date nonsmokers (Johnston & others, 2018).
E-cigarettes—battery-powered devices with a heating element—produce a vapor that users inhale. In most cases the vapor contains nicotine, but the specific contents of “vape” formulas are not regulated (Barrington-Trimis & others, 2017; Gorukanti & others, 2017). While adolescent cigarette use has decreased significantly in recent years, a substantial number of U.S. adolescents are now vaping nicotine. In the national study just described, in 2017, 11.0 percent of twelfth-graders, 8.2 percent of tenth-graders, and 3.5 percent of eighth-graders vaped nicotine (Johnston & others, 2018). Thus, adolescents currently are vaping nicotine more than they are smoking cigarettes. Also, in a recent meta-analysis of longitudinal studies, it was concluded that when adolescents use e-cigarettes they are at increased risk for subsequently smoking cigarettes (Soneji & others, 2018).
The Roles of Development, Parents, Peers, and Education There are serious consequences when adolescents begin to use drugs early in adolescence or even in childhood (Donatelle & Ketcham, 2018). For example, a study revealed that the onset of alcohol use before age 11 was linked to a higher risk of alcohol dependence in early adulthood (Guttmannova & others, 2012). Another study found that early onset of drinking and a quick progression to drinking to intoxication were linked to drinking problems in high school (Morean & others, 2014). Further, a longitudinal study found that earlier age at first use of alcohol was linked to increased risk of heavy alcohol use in early adulthood (Liang & Chikritzhs, 2015). And another study indicated that early- and rapid-onset trajectories of alcohol, marijuana, and substance use were associated with substance abuse in early adulthood (Nelson, Van Ryzin, & Dishion, 2015).
What are some of the ways that parents influence whether their adolescents take drugs?
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Parents play an important role in preventing adolescent drug abuse (Cruz & others, 2018; Garcia-Huidobro & others, 2018; Pena & others, 2017). Positive relationships with parents and others can reduce adolescents’ drug use (Chassin & others, 2016; Eun & others, 2018). Researchers have found that parental monitoring is linked with a lower incidence of drug use (Wang & others, 2014). For example, a recent study revealed that parental monitoring was linked to a lower level of polysubstance use by adolescents (Chan & others, 2017). Also, in a recent intervention study, Latino parents who participated in a program that emphasized the importance of parental monitoring had adolescents with a lower level of drug use than a control group of adolescents whose parents did not participate in the program (Estrada & others, 2017). A research review concluded that the more frequently adolescents ate dinner with their families, the less likely they were to have substance abuse problems (Sen, 2010).
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connecting through research
What Can Families Do to Reduce Drinking and Smoking by Young Adolescents?
Experimental studies have been conducted to determine whether family programs can reduce drinking and smoking by young adolescents. In one experimental study, 1,326 families with 12- to 14-year-old adolescents living in various parts of the United States were interviewed (Bauman & others, 2002). After the baseline interviews, participants were randomly assigned either to go through the Family Matters program (experimental group) or not to experience the program (control group) (Bauman & others, 2002).
The families assigned to the Family Matters program received four mailings of booklets. Each mailing was followed by a telephone call from a health educator to “encourage participation by all family members, answer any questions, and record information” (Bauman & others, 2002, pp. 36–37). The first booklet focused on the negative consequences of adolescent substance abuse to the family. The second emphasized “supervision, support, communication skills, attachment, time spent together, educational achievement, conflict reduction, and how well adolescence is understood.” The third booklet asked parents to list things they do that might inadvertently encourage their child’s use of tobacco or alcohol, identify rules that might influence the child’s use, and consider ways to monitor use. Then adult family members and the child met “to agree upon rules and sanctions related to adolescent use.” Booklet four dealt with “what the child can do to resist peer and media pressures for use.”
Two follow-up interviews with the parents and adolescents were conducted three months and one year after the experimental group had completed the program. Adolescents in the Family Matters program reported lower alcohol and cigarette use at three months and at one year after the program had been completed. Figure 8 shows the results for alcohol.
FIGURE 8 YOUNG ADOLESCENTS’ REPORTS OF ALCOHOL USE IN THE FAMILY MATTERS PROGRAM. Note that at baseline (before the program started) the young adolescents in the Family Matters program (experimental group) and their counterparts who did not go through the program (control group) reported approximately the same lifetime use of alcohol (slightly higher use by the experimental group). However, three months after the program ended, the experimental group reported lower alcohol use, and this reduction was still present one year after the program had ended, although at a reduced level.
Source: Johnston, L. D., et al. Monitoring the Future: National survey results on drug use 2016. Ann Arbor: Institute for Social Research, University of Michigan, 2017.
The topics covered in the second booklet underscore the importance of parental influence earlier in development. For instance, staying actively involved and establishing an authoritative, as opposed to a neglectful, parenting style early in children’s lives will better ensure that children have a clear understanding of the parents’ level of support and expectations when the children reach adolescence.
Along with parents, peers play a very important role in adolescent substance use (Cambron & others, 2018; Choukas-Bradley & Prinstein, 2016; Strong & others, 2017). For example, a large-scale national study of adolescents indicated that friends’ use of alcohol was a stronger influence on adolescent alcohol use than parental use (Deutsch, Wood, & Slutske, 2018).
Academic success is also a strong buffer for the emergence of drug problems in adolescence (Kendler & others, 2018). In one study, early educational achievement considerably reduced the likelihood that adolescents would develop drug problems (Bachman & others, 2008). But what can families do to educate themselves and their children and reduce adolescent drinking and smoking behavior? To find out, see Connecting Through Research.
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EATING DISORDERS
Let’s now examine two eating problems—anorexia nervosa and bulimia nervosa—that are far more common in adolescent girls than boys.
Anorexia Nervosa Although most U.S. girls have been on a diet at some point, slightly less than 1 percent ever develop anorexia nervosa. Anorexia nervosa is an eating disorder that involves the relentless pursuit of thinness through starvation. It is a serious disorder that can lead to death (Pinhas & others, 2017; Westmoreland, Krantz, & Mehler, 2016). Four main characteristics apply to people suffering from anorexia nervosa: (1) weight below 85 percent of what is considered normal for their age and height; (2) an intense fear of gaining weight that does not decrease with weight loss; (3) a distorted image of their body shape (Reville, O’Connor, & Frampton, 2016), and (4) amenorrhea (lack of menstruation) in girls who have reached puberty.
Obsessive thinking about weight and compulsive exercise also are linked to anorexia nervosa (Simpson & others, 2013). Even when they are extremely thin, they see themselves as too fat (Cornelissen & others, 2015). They never think they are thin enough, especially in the abdomen, buttocks, and thighs. They usually weigh themselves frequently, often take their body measurements, and gaze critically at themselves in mirrors.
Anorexia nervosa typically begins in the early to middle adolescent years, often following an episode of dieting and some type of life stress (Fitzpatrick, 2012). It is about 10 times more likely to occur in females than males. When anorexia nervosa does occur in males, the symptoms and other characteristics (such as a distorted body image and family conflict) are usually similar to those reported by females who have the disorder (Ariceli & others, 2005).
Most anorexics are non-Latina White adolescent or young adult females from well-educated middle- and upper-income families and are competitive and high-achieving (Darcy, 2012). They set high standards, become stressed about not being able to reach the standards, and are intensely concerned about how others perceive them (Murray & others, 2017; Stice & others, 2017). Unable to meet these high expectations, they turn to something they can control: their weight. Offspring of mothers with anorexia nervosa are at risk for becoming anorexic themselves (Machado & others, 2014). Problems in family functioning are increasingly being found to be linked to the appearance of anorexia nervosa in adolescent girls (Dimitropoulos & others, 2018; Espie & Eisler, 2015), and research indicates that family therapy is often an effective treatment for adolescent girls with anorexia nervosa (Ganci & others, 2018; Hail & Le Grange, 2018; Hughes & others, 2018).
Anorexia nervosa has become an increasing problem for adolescent girls and young adult women. What are some possible causes of anorexia nervosa?
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Biology and culture are involved in anorexia nervosa. Genes play an important role in anorexia nervosa (Meyre & others, 2018). Also, the physical effects of dieting may change neural networks and thus sustain the disordered pattern (Scaife & others, 2017). The thin fashion-model image in U.S. culture likely contributes to the incidence of anorexia nervosa (Cazzato & others, 2016). The media portray thin as beautiful in their choice of fashion models, whom many adolescent girls strive to emulate. Social media may also fuel the relentless pursuit of thinness by making it easier for anorexic adolescents to find each other online. A recent study found that having an increase in Facebook friends across two years was linked to enhanced motivation to be thin (Tiggemann & Slater, 2017).
Bulimia Nervosa Whereas anorexics control their weight by restricting food intake, most bulimics cannot. Bulimia nervosa is an eating disorder in which the individual consistently follows a binge-and-purge pattern. The bulimic goes on an eating binge and then purges by self-inducing vomiting or using a laxative. Although many people binge and purge occasionally and some experiment with it, a person is considered to have a serious bulimic disorder only if the episodes occur at least twice a week for three months (Castillo & Weiselberg, 2017).
As with anorexics, most bulimics are preoccupied with food, have a strong fear of becoming overweight, are depressed or anxious, and have a distorted body image (Murray & others, 2017; Stice & others, 2017). One study found that bulimics have difficulty controlling their emotions (Lavender & others, 2014). Like adolescents who are anorexic, bulimics are highly perfectionistic (Lampard & others, 2012). Unlike anorexics, individuals who binge and purge typically fall within a normal weight range, which makes bulimia more difficult to detect.
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Approximately 1 to 2 percent of U.S. women are estimated to develop bulimia nervosa, and about 90 percent of bulimics are women. Bulimia nervosa typically begins in late adolescence or early adulthood. Many women who develop bulimia nervosa were somewhat overweight before the onset of the disorder, and the binge eating often began during an episode of dieting. As with anorexia nervosa, about 70 percent of individuals who develop bulimia nervosa eventually recover from the disorder (Agras & others, 2004). Drug therapy and psychotherapy have been effective in treating anorexia nervosa and bulimia nervosa (Agras & others, 2017). Cognitive behavior therapy has especially been helpful in treating bulimia nervosa (Abreu & Cangelli Filho, 2017; Hail & Le Grange, 2018; Peterson & others, 2017).
Review Connect Reflect
LG3 Identify adolescent problems related to health, substance use and abuse, and eating disorders.
Review
- What are key concerns about the health of adolescents?
- What are some characteristics of adolescents’ substance use and abuse?
- What are the characteristics of the major eating disorders?
Connect
- In Connecting Through Research, you learned that attachment was one of the things that the Family Matters program emphasized as important in reducing drinking and smoking behavior in adolescents. Do the research findings discussed in the chapter entitled “Socioemotional Development in Infancy” support or contradict this emphasis on early attachment’s effect on development and behavior later in life?
Reflect Your Own Personal Journey of Life
- How health-enhancing and health-compromising were your patterns of behavior in adolescence? Explain.
4 Adolescent Cognition
LG4 Explain cognitive changes in adolescence.
Piaget’s Theory
Adolescent Egocentrism
Information Processing
Adolescents’ developing power of thought opens up new cognitive and social horizons. Let’s examine some explanations of how their power of thought develops, beginning with Piaget’s theory (1952).
PIAGET’S THEORY
Jean Piaget proposed that around 7 years of age children enter the concrete operational stage of cognitive development. They can reason logically about concrete events and objects, and they make gains in their ability to classify objects and to reason about the relationships between classes of objects. Around age 11, according to Piaget, the fourth and final stage of cognitive development—the formal operational stage—begins.
developmental connection
Cognitive Theory
Is there a fifth, postformal stage of cognitive development that characterizes young adults? Connect to “Physical and Cognitive Development in Early Adulthood.”
The Formal Operational Stage What are the characteristics of the formal operational stage? Formal operational thought is more abstract than concrete operational thought. Adolescents are no longer limited to actual, concrete experiences as anchors for thought. They can conjure up make-believe situations, abstract propositions, and events that are purely hypothetical, and can try to reason logically about them.
The abstract quality of thinking during the formal operational stage is evident in the adolescent’s verbal problem-solving ability. Whereas the concrete operational thinker needs to see the concrete elements A, B, and C to be able to make the logical Page 359inference that if A = B and B = C, then A = C, the formal operational thinker can solve this problem merely through verbal presentation.
Another indication of the abstract quality of adolescents’ thought is their increased tendency to think about thought itself. One adolescent commented, “I began thinking about why I was thinking what I was. Then I began thinking about why I was thinking about what I was thinking about what I was.” If this sounds abstract, it is, and it characterizes the adolescent’s enhanced focus on thought and its abstract qualities.
Accompanying the abstract nature of formal operational thought is thought full of idealism and possibilities, especially during the beginning of the formal operational stage, when assimilation dominates. Adolescents engage in extended speculation about ideal characteristics—qualities they desire in themselves and in others. Such thoughts often lead adolescents to compare themselves with others in regard to such ideal standards. And their thoughts are often fantasy flights into future possibilities.
Might adolescents’ ability to reason hypothetically and to evaluate what is ideal versus what is real lead them to engage in demonstrations such as this protest related to improving education? What other causes might be attractive to adolescents’ newfound cognitive abilities of hypothetical-deductive reasoning and idealistic thinking?
©Jim West/Alamy
At the same time that adolescents think more abstractly and idealistically, they also think more logically. Children are likely to solve problems through trial and error; adolescents begin to think more as a scientist thinks, devising plans to solve problems and systematically testing solutions. This type of problem solving requires hypothetical-deductive reasoning, which involves creating a hypothesis and deducing its implications, steps that provide ways to test the hypothesis. Thus, formal operational thinkers develop hypotheses about ways to solve problems and then systematically deduce the best path to follow to solve the problem.
Evaluating Piaget’s Theory Researchers have challenged some of Piaget’s ideas about the formal operational stage (Reyna & Zayas, 2014). Among their findings is that there is much more individual variation than Piaget envisioned: Only about one in three young adolescents is a formal operational thinker, and many American adults (and adults in other cultures) never become formal operational thinkers.
Furthermore, education in the logic of science and mathematics promotes the development of formal operational thinking. This point recalls a criticism of Piaget’s theory that suggests culture and education exert stronger influences on cognitive development than Piaget maintained (Petersen & others, 2017; Wagner, 2018).
Piaget’s theory of cognitive development has been challenged on other points as well. Children’s cognitive development is not as stage-like as Piaget envisioned (Siegler, 2017; Wu & Scerif, 2018). Because some cognitive abilities have found to emerge earlier than Piaget thought, and others later, children do not appear to move neatly from one stage to another (Bauer, 2018; Liu & Spelke, 2017). Other evidence casting doubt on the stage notion is that children often show more understanding on one task than on another, similar task.
Many adolescent girls spend long hours in front of the mirror, depleting cans of hairspray, tubes of lipstick, and jars of cosmetics. How might this behavior be related to changes in adolescent cognitive and physical development?
©Image Source/Getty Images
Despite these challenges to Piaget’s ideas, we owe him a tremendous debt (Miller, 2016). Piaget was the founder of the present field of cognitive development, and he developed a long list of masterful concepts of enduring power and fascination: assimilation, accommodation, object permanence, egocentrism, conservation, and others. Psychologists also owe him the current vision of children as active, constructive thinkers. And they are indebted to him for creating a theory that has generated a huge volume of research on children’s cognitive development (Miller, 2016).
Piaget also was a genius when it came to observing children. His careful observations demonstrated inventive ways to discover how children act on and adapt to their world. He showed us how children need to make their experiences fit their schemes yet simultaneously adapt their schemes to accommodate their experiences. And Piaget revealed how cognitive change is likely to occur if the context is structured to allow gradual movement to the next higher level.
ADOLESCENT EGOCENTRISM
Adolescent egocentrism is the heightened self-consciousness of adolescents. David Elkind (1976) points out that adolescent egocentrism has two key components—the imaginary audience and personal fable. The imaginary audience is reflected in adolescents’ belief that others are as interested in them as they themselves Page 360are, as well as attention-getting behavior—attempts to be noticed, visible, and “on stage.” For example, an eighth-grade boy might walk into a classroom and think that all eyes are riveted on his spotty complexion. Adolescents sense that they are “on stage” in early adolescence, believing they are the main actors and all others are the audience.
According to Elkind, the personal fable is the part of adolescent egocentrism involving a sense of uniqueness and invincibility (or invulnerability). For example, 13-year-old Adrienne says this about herself: “No one understands me, particularly my parents. They have no idea of what I am feeling.” Adolescents’ sense of personal uniqueness makes them believe that no one can understand how they really feel. As part of their effort to retain a sense of personal uniqueness, adolescents might craft a story about the self that is filled with fantasy, immersing themselves in a world that is far removed from reality. Personal fables frequently show up in adolescent diaries.
Might frequent use of social media, such as Facebook, increase adolescents’ egocentrism?
©Brendan O’Sullivan/Photolibrary/Getty Images
Adolescents often have been portrayed as having a sense of invincibility or invulnerability. For example, during a conversation with a girl who is the same age, 14-year-old Margaret says, “Are you kidding? I won’t get pregnant.” This sense of invincibility may lead adolescents to believe that they themselves are invulnerable to dangers and catastrophes (such as deadly car wrecks) that happen to other people. As a result, some adolescents engage in risky behaviors such as drag racing, drug use, suicide attempts, and having sexual intercourse without using contraceptives or barriers against STIs (Alberts, Elkind, & Ginsberg, 2007).
developmental connection
Cognitive Theory
Piaget described a form of egocentrism that characterizes young children. Connect to “Physical and Cognitive Development in Early Childhood.”
Might social media be an amplification tool for adolescent egocentrism? Earlier generations of adolescents did not have social media to connect with large numbers of people; instead, they connected with fewer people, either in person or via telephone. Might today’s teens be drawn to social media and its virtually unlimited friend base to express their imaginary audience and sense of uniqueness? One analysis concluded that amassing a large number of friends (audience) may help to validate adolescents’ perception that their life is on stage and everyone is watching them (Psychster Inc, 2010). A recent meta-analysis concluded that a greater use of social networking sites was linked to a higher level of narcissism (Gnambs & Appel, 2018).
developmental connection
The Brain
The prefrontal cortex is the location in the brain where much of executive function occurs. Connect to “Physical and Cognitive Development in Early Childhood.”
What about having a sense of invulnerability—is that aspect of adolescent egocentrism as accurate as Elkind argues? An increasing number of research studies suggest that rather than perceiving themselves to be invulnerable, adolescents tend to portray themselves as vulnerable to experiencing a premature death (Reyna & Rivers, 2008). For example, in one study, 12- to 18-year-olds were asked about their chances of dying in the next year and prior to age 20 (Fischhoff & others, 2010). The adolescents greatly overestimated their chance of dying prematurely.
INFORMATION PROCESSING
Deanna Kuhn (2009) identified some important characteristics of adolescents’ information processing and thinking. In her view, in the later years of childhood and continuing in adolescence, individuals approach cognitive levels that may or may not be achieved, in contrast to the largely universal cognitive levels that young children attain. By adolescence, considerable variation in cognitive functioning is present across individuals. This variability supports the argument that adolescents are producers of their own development to a greater extent than are children.
Kuhn (2009) further argues that the most important cognitive change in adolescence is improvement in executive function—an umbrella-like concept that consists of a number of higher-level cognitive processes linked to the development of the prefrontal cortex (Crone, Peters, & Steinbeis, 2018; Gerst & others, 2017). Executive function involves managing one’s thoughts to engage in goal-directed behavior and to exercise self-control (Bardikoff & Sabbagh, 2017; Knapp & Morton, 2017; Wiebe & Karbach, 2018). Our further coverage of executive function in adolescence focuses on cognitive control, decision making, and critical thinking.
Cognitive Control Earlier you read about the increase Page 361in cognitive control that occurs in middle and late childhood. Recall that cognitive control involves effective control in a number of areas, including controlling attention, reducing interfering thoughts, and being cognitively flexible (Stewart & others, 2017). Cognitive control continues to increase in adolescence and emerging adulthood (Chevalier, Dauvier, & Blaye, 2018; Romer, Reyna, & Satterthwaite, 2017; Somerville, 2016).
Think about all the times adolescents need to engage in cognitive control, such as the following situations (Galinsky, 2010):
- making a real effort to stick with a task, avoiding interfering thoughts or environmental events, and instead doing what is most effective;
- stopping and thinking before acting to avoid blurting out something that a minute or two later they wished they hadn’t said;
- continuing to work on something that is important but boring when there is something a lot more fun to do, inhibiting their behavior and doing the boring but important task, saying to themselves, “I have to show the self-discipline to finish this.”
What are some different aspects of cognitive control that can benefit adolescents’ development?
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Control Attention and Reduce Interfering Thoughts Controlling attention is a key aspect of learning and thinking in adolescence and emerging adulthood (Lau & Waters, 2017; Mueller & others, 2017). Distractions that can interfere with attention in adolescence and emerging adulthood come from the external environment (other students talking while the student is trying to listen to a lecture, or the student turning on a laptop or tablet PC during a lecture and looking at a new friend request on Facebook, for example) or intrusive distractions from competing thoughts in the individual’s mind. Self-oriented thoughts, such as worrying, self-doubt, and intense emotionally laden thoughts may especially interfere with focusing attention on thinking tasks (Gillig & Sanders, 2011).
Be Cognitively Flexible Cognitive flexibility involves being aware that options and alternatives are available and adapting to the situation (Buttelmann & Karbach, 2017; Wang, Ye, & Degol, 2017). Before adolescents and emerging adults adapt their behavior in a situation, they must be aware that they need to change their way of thinking and be motivated to do so (Gopnik & others, 2018). Having confidence in their ability to adapt their thinking to a particular situation, an aspect of self-efficacy, also is important in being cognitively flexible (Bandura, 2012).
Decision Making Adolescence is a time of increased decision making—which friends to choose; which person to date; whether to have sex, buy a car, go to college, and so on (Helm & Reyna, 2018; Meschkow & others, 2018; Reyna, 2018; Romer, Reyna, & Satterthwaite, 2017; Steinberg & others, 2018; van den Bos & Hertwig, 2017). How competent are adolescents at making decisions? Older adolescents are described as more competent than younger adolescents, who in turn are more competent than children (Keating, 1990). Compared with children, young adolescents are more likely to generate different options, examine a situation from a variety of perspectives, anticipate the consequences of decisions, and consider the credibility of sources.
Most people make better decisions when they are calm than when they are emotionally aroused. That may especially be true for adolescents, who have a tendency to be emotionally intense (Cohen & Casey, 2017). The same adolescent who makes a wise decision when calm may make an unwise decision when emotionally aroused. In the heat of the moment, emotions may overwhelm decision-making ability (Goddings & Mills, 2017).
How do emotions and social contexts influence adolescents’ decision making?
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The social context plays a key role in adolescent decision making (Breiner & others, 2018; Sherman, Steinberg, & Chein, 2018; Silva & others, 2017). For example, adolescents’ willingness to make risky decisions is more likely to occur in contexts where substances and other temptations are readily available (Helm & Reyna, 2018; Meschkow & others, 2018; Reyna, 2018; Reyna & Rivers, 2008). Recent research reveals that the presence of peers in risk-taking situations increases the likelihood that adolescents will make risky decisions (Silva & others, 2017; Steinberg, 2015a, b). In a recent study, adolescents took greater risks and showed stronger Page 362preference for immediate rewards when they were with three same-aged peers than when they were alone (Silva, Chein, & Steinberg, 2016).
To better understand adolescent decision making, Valerie Reyna and her colleagues (Helm & Reyna, 2018; Meschkow & othes, 2018; Reyna, 2018; Reyna & Farley, 2006; Reyna & others, 2011, 2015, 2017; Romer, Reyna, & Satterthwaite, 2017) have proposed the fuzzy-trace theory dual-process model, which states that decision making is influenced by two cognitive systems—“verbatim” analytical (literal and precise) and gist-based intuitional (simple bottom-line meaning)—which operate in parallel. Basing judgments and decisions on simple gist is viewed as more beneficial than analytical thinking to adolescents’ decision making. In this view, adolescents don’t benefit from engaging in reflective, detailed, higher-level cognitive analysis about a decision, especially in high-risk, real-world contexts where they would get bogged down in trivial detail. In such contexts, adolescents need to rely on their awareness that some circumstances are simply so dangerous that they must be avoided at all costs.
In risky situations it is important for an adolescent to quickly get the gist, or meaning, of what is happening and glean that the situation is a dangerous context, which can cue personal values that will protect the adolescent from making a risky decision (Helm, McCormick, & Reyna, 2018; Helm & Reyna, 2018; Meschkow & others, 2018; Rahimi-Golkhandan & others, 2017; Reyna, 2018; Reyna & others, 2011, 2015; Romer, Reyna, & Satterthwaite, 2017). An experiment showed that encouraging gist-based thinking about risks (along with factual information) reduced self-reported risk taking up to one year after exposure to the curriculum (Reyna & Mills, 2014). However, some experts on adolescent cognition argue that in many cases adolescents benefit from both analytical and experiential systems (Kuhn, 2009).
Adolescents need more opportunities to practice and discuss realistic decision making. Many real-world decisions on matters such as sex, drugs, and daredevil driving occur in an atmosphere of stress that includes time constraints and emotional involvement. One strategy for improving adolescent decision making is to provide more opportunities for them to engage in role playing and peer group problem solving.
Critical Thinking Adolescence is an important transitional period in the development of critical thinking (Keating, 1990). In one study of fifth-, eighth-, and eleventh-graders, critical thinking increased with age but still occurred in only 43 percent of even the eleventh-graders, and many adolescents showed self-serving biases in their reasoning.
If fundamental skills (such as literacy and math skills) are not developed during childhood, critical-thinking skills are unlikely to mature in adolescence. For the subset of adolescents who lack such fundamental skills, potential gains in adolescent thinking are unlikely. For other adolescents, however, cognitive changes that allow improved critical thinking in adolescence include the following: (1) increased speed, automaticity, and capacity of information processing, which free cognitive resources for other purposes; (2) more breadth of content knowledge in a variety of domains; (3) increased ability to construct new combinations of knowledge; and (4) a greater range and more spontaneous use of strategies or procedures for applying or obtaining knowledge, such as planning, considering alternatives, and cognitive monitoring.
Review Connect Reflect
LG4 Explain cognitive changes in adolescence.
Review
- What is Piaget’s theory of adolescent cognitive development?
- What is adolescent egocentrism?
- What are some important aspects of information processing in adolescence?
Connect
- Egocentrism was also mentioned earlier in the context of early childhood cognitive development. How is adolescent egocentrism similar to or different from egocentrism in early childhood?
Reflect Your Own Personal Journey of Life
- Evaluate the level of your thinking as you made the transition to adolescence and through adolescence. Does Piaget’s stage of formal operational thinking accurately describe the changes that occurred in your thinking? Explain.
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5 Schools
LG5 Summarize some key aspects of how schools influence adolescent development.
The Transition to Middle or Junior High School
Effective Schools for Young Adolescents
High School
Extracurricular Activities
Service Learning
What is the transition from elementary to middle or junior high school like? What are the characteristics of effective schools for adolescents? How can adolescents benefit from service learning?
THE TRANSITION TO MIDDLE OR JUNIOR HIGH SCHOOL
The first year of middle school or junior high school can be difficult for many students (Wigfield, Rosenzweig, & Eccles, 2017; Wigfield, Tonks, & Klauda, 2016). For example, in one study of the transition from sixth grade in an elementary school to seventh grade in a junior high school, adolescents’ perceptions of the quality of their school life plunged in the seventh grade (Hirsch & Rapkin, 1987). Compared with their earlier feelings as sixth-graders, the seventh-graders were less satisfied with school, were less committed to school, and liked their teachers less. The drop in school satisfaction occurred regardless of how academically successful the students were. The transition to middle or junior high school is less stressful when students have positive relationships with friends and go through the transition in team-oriented schools where 20 to 30 students take the same classes together (Hawkins & Berndt, 1985).
The transition to middle or junior high school takes place at a time when many changes—in the individual, in the family, and in school—are occurring simultaneously (Wigfield & others, 2015; Wigfield, Rosenzweig, & Eccles, 2017; Wigfield, Tonks, & Klauda, 2016). These changes include puberty and related concerns about body image; the emergence of at least some aspects of formal operational thought and changes in social cognition; increased responsibility and decreased dependency on parents; change to a larger, more impersonal school structure; change from one teacher to many teachers and from a small, homogeneous set of peers to a larger, more heterogeneous set of peers; and an increased focus on achievement and performance. Moreover, when students make the transition to middle or junior high school, they experience the top-dog phenomenon, moving from being the oldest, biggest, and most powerful students in the elementary school to being the youngest, smallest, and least powerful students in the middle or junior high school.
The transition from elementary to middle or junior high school occurs at the same time as a number of other developmental changes. What are some of these other developmental changes?
©Creatas/PunchStock
The transition to middle or junior high school also can have positive aspects. Students are more likely to feel grown up, have more subjects from which to select, have more opportunities to spend time with peers and locate compatible friends, and enjoy increased independence from direct parental monitoring. They also may be more challenged intellectually by academic work.
EFFECTIVE SCHOOLS FOR YOUNG ADOLESCENTS
Critics argue that middle and junior high schools should offer activities that reflect a wide range of individual differences in biological and psychological development among young adolescents. In 1989 the Carnegie Corporation issued an extremely negative evaluation of U.S. middle schools. It concluded that most young adolescents attended massive, impersonal schools; were taught from irrelevant curricula; trusted few adults in school; and lacked access to health care and counseling. It recommended that the nation develop smaller “communities” or “houses” to lessen the impersonal nature of large middle schools, have lower student-to-counselor ratios (10 to 1 instead of several hundred to 1), involve parents and community leaders in schools, develop new curricula, have teachers team teach in more flexibly designed curriculum blocks that integrate several disciplines, boost students’ health and fitness with more in-school programs, and help students who need public health care to get it. Twenty years later, experts are still finding that middle schools throughout the nation need a major redesign if they are to be effective in educating adolescents (Roeser, 2016; Wigfield & others, 2015).
To read about one individual whose main career focus is improving middle school students’ learning and education, see Connecting with Careers.
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connecting with careers
Katherine McMillan Culp, Research Scientist at an Educational Center
Katherine McMillan Culp wanted mainly to live in New York City when she graduated from college and became a receptionist at a center that focused on children and technology. More than 20 years later she is leading research projects at the center (Center for Children and Technology). Not long after her receptionist job, she combined work at the center with graduate school at Columbia University. Culp became especially interested in how content and instruction can best be created to link with the developmental level of children and adolescents.
Today she holds the position of principal research scientist at Education Development Center, directing a number of projects. One of her main current interests is middle school students’ science learning. In this area, she consults with game designers, teachers, and policy makers to improve their understanding of how adolescents think and learn.
Her advice to anyone wanting to do this type of work outside of academia is to get the best education and training possible, then become connected with schools, work with teachers, and obtain experience related to practical problems involved with schools and learning (Culp, 2012).
HIGH SCHOOL
Just as there are concerns about U.S. middle school education, so are there concerns about U.S. high school education (Kitsantas & Cleary, 2016). A recent analysis indicated that only 25 percent of U.S. high school graduates have the academic skills to succeed in college (Bill & Melinda Gates Foundation, 2017). Not only are many high school graduates poorly prepared for college, they also are poorly prepared for the demands of the modern, high-performance workplace (Bill & Melinda Gates Foundation, 2018).
Critics stress that in many high schools expectations for success and standards for learning are too low. Critics also argue that too often high schools foster passivity and that schools should create a variety of pathways for students to achieve an identity. Many students graduate from high school with inadequate reading, writing, and math skills—including many who go on to college and must enroll in remediation classes there. Other students drop out of high school and do not have skills that will allow them to obtain decent jobs, much less to be informed citizens.
The transition to high school can have problems just as the transition to middle school does. For example, high schools are often even larger, more bureaucratic, and more impersonal than middle schools are; there isn’t much opportunity for students and teachers to get to know each other, which can lead to distrust; and teachers rarely make content relevant to students’ interests (Eccles & Roeser, 2016). Such experiences likely undermine the motivation of students.
Robert Crosnoe’s (2011) book, Fitting In, Standing Out, highlighted another major problem with U.S. high schools: how the negative social aspects of adolescents’ lives undermine their academic achievement. In his view, adolescents become immersed in complex peer group cultures that demand conformity. High school is supposed to be about getting an education, but for many youth it is about navigating the social worlds of peer relations that may or may not value education and academic achievement. Adolescents who fail to fit in, especially those who are obese or gay, become stigmatized. Crosnoe recommends increased school counseling services, expanded extracurricular activities, and improved parental monitoring to reduce such problems (Crosnoe & Benner, 2015).
Dropout Rates Yet another concern about U.S. high schools involves students dropping out of school. In the last half of the twentieth century and the first decade of the twenty-first century, U.S. high school dropout rates declined (National Center for Education Statistics, 2017). In the 1940s, more than half of U.S. 16- to 24-year-olds had dropped out of school; by 2015, this figure had decreased to 5.9 percent. The dropout rate of Latino adolescents remains high, although it has been decreasing considerably in the twenty-first century (from 27.8 percent in 2000 to 9.2 percent in 2016). The lowest dropout rate in 2015 was for Asian American adolescents Page 365(2.1 percent), followed by non-Latino White adolescents (4.6 percent), African American adolescents (6.5 percent), and Latino adolescents
(9.2 percent) (National Center for Education Statistics, 2017).
National data on Native American adolescents are inadequate because statistics have been collected sporadically and/or from small samples. However, there are some indications that Native American adolescents may have the highest school dropout rate.
Gender differences have characterized U.S. dropout rates for many decades, but they have been narrowing in recent years. In 2015, the dropout rate for males was 6.3 percent and for females it was 5.4 percent (National Center for Education Statistics, 2017).
The average U.S. high school dropout rates just described mask some very high dropout rates in low-income areas of inner cities. For example, in cities such as Detroit, Cleveland, and Chicago, dropout rates are higher than 50 percent. Also, the percentages cited earlier are for 16- to 24-year-olds. When dropout rates are calculated in terms of students who do not graduate from high school within four years, the percentage of students who drop out is also much higher. Thus, in considering high school dropout rates, it is important to examine age, the number of years it takes to complete high school, and various contexts including ethnicity, gender, and school location.
An important educational goal is to increase the high school graduation rate of Native youth. An excellent strategy to accomplish this goal is high quality early childhood educational programs such as this one at St. Bonaventure Indian School on the Navajo Nation in Thoreau, New Mexico.
©Jim West/Alamy
Students drop out of school for many reasons (Dupere & others, 2015). In one study, almost 50 percent of the dropouts cited school-related reasons for leaving school, such as not liking school or being expelled or suspended (Rumberger, 1983). Twenty percent of the dropouts (but 40 percent of the Latino students) cited economic reasons for leaving school. One-third of the female students dropped out for personal reasons such as pregnancy or marriage.
According to a research review, the most effective programs to discourage dropping out of high school provide early intervention for reading problems, tutoring, counseling, and mentoring (Lehr & others, 2003). Clearly, then, early detection of children’s school-related difficulties and getting children engaged with school in positive ways are important strategies for reducing the dropout rate (Crosnoe, Bonazzo, & Wu, 2015).
One program that has been very effective in reducing school dropout rates is “I Have a Dream” (IHAD), an innovative, comprehensive, long-term dropout prevention program administered by the National “I Have a Dream” Foundation in New York (“I Have a Dream” Foundation, 2017). It has grown to encompass more than 180 projects in 64 cities and 28 states plus Washington, DC, and New Zealand, serving more than 16,000 children (“I Have a Dream” Foundation, 2017). Local IHAD projects around the country “adopt” entire grades (usually the third or fourth) from public elementary schools, or corresponding age cohorts from public housing developments. These children—“Dreamers”—are then provided with a program of academic, social, cultural, and recreational activities throughout their elementary, middle school, and high school years. Evaluations of IHAD programs have found improvements in grades, test scores, and school attendance, as well as a reduction in behavioral problems among Dreamers (Davis, Hyatt, & Arrasmith, 1998).
EXTRACURRICULAR ACTIVITIES
Adolescents in U.S. schools usually can choose from a wide array of extracurricular activities in addition to their academic courses. These adult-sanctioned activities typically occur during the after-school hours and can be sponsored either by the school or by the community. They include such diverse activities as sports, academic clubs, band, drama, and math clubs. Researchers have found that participation in extracurricular activities is linked to higher grades, greater school engagement, less likelihood of dropping out of school, improved probability of going to college, higher self-esteem, and lower rates of depression, delinquency, and substance abuse (Denault & Guay, 2017; Simpkins, Fredricks, & Eccles, 2015; Wigfield & others, 2015). A recent study revealed that immigrant adolescents who participated in extracurricular activities improved their academic achievement and increased Page 366their school engagement (Camacho & Fuligni, 2015). Adolescents gain more benefit from a breadth of extracurricular activities than from focusing on a single extracurricular activity.
These adolescents are participating in the “I Have a Dream” (IHAD) Program, a comprehensive, long-term dropout prevention program that has been very successful. What are some other strategies for reducing high school dropout rates?
Courtesy of “I Have a Dream” Foundation of Boulder County (www.ihadboulder.org)
Of course, the quality of the extracurricular activities matters (Simpkins, Fredricks, & Eccles, 2015). High-quality extracurricular activities that are likely to promote positive adolescent development provide competent, supportive adult mentors; opportunities for increasing school connectedness; challenging and meaningful activities; and opportunities for improving skills.
What are some of the positive effects of service learning?
©Ariel Skelley/Blend Images
SERVICE LEARNING
Service learning is a form of education that promotes social responsibility and service to the community. In service learning, adolescents engage in activities such as tutoring, helping older adults, working in a hospital, assisting at a child-care center, or cleaning up a vacant lot to make a play area. An important goal of service learning is that adolescents become less self-centered and more strongly motivated to help others (Hart, Goel, & Atkins, 2017; Hart & van Goethem, 2017; Hart & others, 2017; Kackar-Cam & Schmidt, 2014). Service learning is often more effective when two conditions are met (Nucci, 2006): (1) giving students some degree of choice in the service activities in which they participate, and (2) providing students opportunities to reflect about their participation.
Researchers have found that service learning benefits adolescents in a number of ways (Hart & others, 2017). Improvements in adolescent development related to service learning include higher grades in school, increased goal setting, higher self-esteem, and a greater sense of being able to make a difference for others (Hart & van Goethem, 2017). Also, one study revealed that adolescents’ volunteer activities provided opportunities to explore and reason about moral issues (van Goethem & others, 2012).
Review Connect Reflect
LG5 Summarize some key aspects of how schools influence adolescent development.
Review
- What is the transition to middle or junior high school like?
- What are some characteristics of effective schools for young adolescents?
- What are some important things to know about high school dropouts and improving high schools?
- How does participation in extracurricular activities influence adolescent development?
- What is service learning, and how does it affect adolescent development?
Connect
- Compare the optimal school learning environments for adolescents described in this chapter with those described for younger children in previous chapters. Aside from age-appropriate curricula, what else is similar or different?
Reflect Your Own Personal Journey of Life
- What was your middle or junior high school like? How did it measure up to the Carnegie Corporation’s recommendations?
topical connections looking forward
From 18 to 25 years of age, individuals make a transition from adolescence to adulthood. This transitional period, called emerging adulthood, is characterized by identity exploration, instability, and awareness of possibilities. Individuals often reach the peak of their physical skills between 19 and 26 years of age, followed by declining physical development during the early thirties. Cognitive development becomes more pragmatic and realistic, as well as more reflective and relativistic. Work becomes a more central aspect of individuals’ lives.
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reach your learning goals
Physical and Cognitive Development in Adolescence
1 The Nature of Adolescence
LG1 Discuss the nature of adolescence.
- Many stereotypes of adolescents are too negative. Most adolescents today successfully negotiate the path from childhood to adulthood. However, too many of today’s adolescents are not provided with adequate opportunities and support to become competent adults. It is important to view adolescents as a heterogeneous group because different portraits of adolescents emerge, depending on the particular set of adolescents being described.
- Social policy regarding adolescents too often has focused on health-compromising behaviors and not enough on strength-based approaches. Adolescents need more caring adults in their lives.
2 Physical Changes
LG2 Describe the changes involved in puberty, as well as changes in the brain and sexuality during adolescence.
Puberty
The Brain
Adolescent Sexuality
- Puberty is a period of rapid physical maturation involving hormonal and bodily changes that occur primarily during early adolescence. Determinants of pubertal timing include nutrition, health, and heredity. The pubertal growth spurt begins at an average age of 9 years for girls and 11 for boys, reaching a peak at 11½ for girls and 13½ for boys. Individual variation in pubertal changes is substantial.
- Adolescents show considerable interest in their body image, with girls having more negative body images than boys do. For boys, early maturation brings benefits, at least during early adolescence. Early-maturing girls are vulnerable to a number of risks.
- Changes in the brain during adolescence involve the thickening of the corpus callosum and a gap in maturation between the limbic system and the prefrontal cortex, which functions in reasoning and self-regulation.
- Adolescence is a time of sexual exploration and sexual experimentation. Having sexual intercourse in early adolescence is associated with negative developmental outcomes.
- Contraceptive use by adolescents is increasing. About one in four sexually experienced adolescents acquires a sexually transmitted infection (STI). The adolescent pregnancy rate is higher in the United States than in other industrialized nations, but the U.S. rate of adolescent pregnancy has been decreasing in recent years.
3 Issues in Adolescent Health
LG3 Identify adolescent problems related to health, substance use and abuse, and eating disorders.
Adolescent Health
Substance Use and Abuse
Eating Disorders
- Adolescence is a critical juncture in health because many of the factors related to poor health habits and early death in the adult years begin during adolescence. Poor nutrition, lack of exercise, and inadequate sleep are concerns. The three leading causes of death in adolescence are unintentional injuries, homicide, and suicide.
- Despite recent declines, the United States has one of the highest rates of adolescent illicit drug use of any industrialized nation. Alcohol abuse is a major adolescent problem, although its rate has been dropping in recent years, as has the rate of cigarette smoking. Parents, peers, social support, and educational success play important roles in determining whether adolescents take drugs.
- Eating disorders have increased in adolescence, along with the percentage of adolescents who are overweight. Two eating disorders that may emerge in adolescence are anorexia nervosa and bulimia nervosa. Anorexia nervosa typically starts in the early to middle adolescent years following a dieting episode and involves the relentless pursuit of thinness through starvation. Bulimia nervosa involves a binge-and-purge pattern, and bulimics (unlike anorexics) typically fall within a normal weight range.
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4 Adolescent Cognition
LG4 Explain cognitive changes in adolescence.
Piaget’s Theory
Adolescent Egocentrism
Information Processing
- During the formal operational stage, Piaget’s fourth stage of cognitive development, thinking becomes more abstract, idealistic, and logical than during the concrete operational stage. However, many adolescents are not formal operational thinkers but are consolidating their concrete operational thought.
- Elkind describes adolescent egocentrism as the heightened self-consciousness of adolescents that consists of two parts: the imaginary audience and the personal fable. Recent research questions whether adolescents perceive themselves to be invulnerable.
- Adolescence is characterized by a number of advances in executive function. Cognitive control involves effective control and flexible thinking in a number of areas, including controlling attention, reducing interfering thoughts, remaining cognitively flexible, making decisions, and thinking critically.
5 Schools
LG5 Summarize some key aspects of how schools influence adolescent development.
The Transition to Middle or Junior High School
Effective Schools for
Young Adolescents
High School
Extracurricular Activities
Service Learning
- The transition to middle or junior high school coincides with many social, familial, and individual changes in the adolescent’s life, and this transition is often stressful. One source of stress is the move from the top-dog position to the lowest position in school.
- Some critics argue that a major redesign of U.S. middle schools is needed. Critics say that U.S. high schools foster passivity and do not develop students’ academic skills adequately. Characteristics of effective schools include lower student-to-counselor ratios, involvement of parents and community leaders in schools, team teaching, and efforts to boost students’ health and fitness.
- A number of strategies have been proposed for improving U.S. high schools, including raising expectations and providing better support. The overall high school dropout rate declined considerably in the last half of the twentieth century, but the dropout rates among Latino and Native American youth remain very high.
- Participation in extracurricular activities is associated with positive academic and psychological outcomes. Adolescents benefit from participating in a variety of extracurricular activities; the quality of the activities also matters.
- Service learning, a form of education that promotes social responsibility and service to the community, has been linked with positive benefits for adolescents such as higher grades, increased goal setting, and improved self-esteem.
key terms
fuzzy-trace theory dual-process model
hypothetical-deductive reasoning
sexually transmitted infections (STIs)
key people
David Elkind
Deanna Kuhn
Lloyd Johnston
Jean Piaget
Valerie Reyna
Link (webpage):
Course Outcomes (CO): 1, 3, 4, 5
chapter 1
INTRODUCTION
chapter outline
Learning Goal 1 Discuss the distinctive features of a life-span perspective on development.
The Importance of Studying Life-Span Development
Characteristics of the Life-Span Perspective
Learning Goal 2 Identify the most important processes, periods, and issues in development.
Biological, Cognitive, and Socioemotional Processes
Learning Goal 3 Describe the main theories of human development.
Behavioral and Social Cognitive Theories
An Eclectic Theoretical Orientation
4 Research on Life-Span Development
Learning Goal 4 Explain how research on life-span development is conducted.
©Ariel Skelley/Blend Images LLC
Page 3
Ted Kaczynski sprinted through high school, not bothering with his junior year and making only passing efforts at social contact. Off to Harvard at age 16, Kaczynski was a loner during his college years.
One of his roommates at Harvard said that he avoided people by quickly shuffling by them and slamming the door behind him. After obtaining his Ph.D. in mathematics at the University of Michigan, Kaczynski became a professor at the University of California at Berkeley. His colleagues there remember him as hiding from social contact—no friends, no allies, no networking.
Ted Kaczynski, the convicted Unabomber, traced his difficulties to growing up as a genius in a kid’s body and not fitting in when he was a child.©Seanna O’Sullivan
After several years at Berkeley, Kaczynski resigned and moved to a rural area of Montana where he lived as a hermit in a crude shack for 25 years. Town residents described him as a bearded eccentric. Kaczynski traced his own difficulties to growing up as a genius in a kid’s body and sticking out like a sore thumb in his surroundings as a child. In 1996, he was arrested and charged as the notorious Unabomber, America’s most-wanted killer. Over the course of 17 years, Kaczynski had sent 16 mail bombs that left 23 people wounded or maimed and 3 people dead. In 1998, he pleaded guilty to the offenses and was sentenced to life in prison.
Ted Kaczynski, about age 15–16.©WBBM-TV/AFP/Getty Images
A decade before Kaczynski mailed his first bomb, Alice Walker spent her days battling racism in Mississippi. She had recently won her first writing fellowship, but rather than use the money to follow her dream of moving to Senegal, Africa, she put herself into the heart and heat of the civil rights movement. Walker had grown up knowing the brutal effects of poverty and racism. Born in 1944, she was the eighth child of Georgia sharecroppers who earned $300 a year. When Walker was 8, her brother accidentally shot her in the left eye with a BB gun. By the time her parents got her to the hospital a week later (they had no car), she was blind in that eye, and it had developed a disfiguring layer of scar tissue. Despite the counts against her, Walker overcame pain and anger and went on to win a Pulitzer Prize for her book The Color Purple. She became not only a novelist but also an essayist, a poet, a short-story writer, and a social activist.
Alice Walker won the Pulitzer Prize for her book The Color Purple. Like the characters in her book, Walker overcame pain and anger to triumph and celebrate the human spirit.©AP ImagesAlice Walker, about age 8.Courtesy of Alice Walker
Page 4
preview
What leads one individual, so full of promise, to commit brutal acts of violence and another to turn poverty and trauma into a rich literary harvest? If you have ever wondered why people turn out the way they do, you have asked yourself the central question we will be exploring. This text traces the journey of human development—your own and that of every other member of the human species. In this chapter, we will explore what it means to take a life-span perspective on development, examine the nature of development, and outline how science helps us to understand it.
1 The Life-Span Perspective
LG1 Discuss the distinctive features of a life-span perspective on development.
The Importance of Studying Life-Span Development
Characteristics of the Life-Span Perspective
Some Contemporary Concerns
Each of us develops partly like all other individuals, partly like some other individuals, and partly like no other individual. Most of the time our attention is directed to each individual’s uniqueness. But as humans, we have all traveled some common paths. Each of us—Leonardo da Vinci, Joan of Arc, George Washington, Martin Luther King, Jr., and you—walked at about 1 year, engaged in fantasy play as a young child, and became more independent as a youth. Each of us, if we live long enough, will experience hearing problems and the death of family members and friends. This is the general course of our development, the pattern of movement or change that begins at conception and continues through the human life span.
We reach backward to our parents and forward to our children, and through their children to a future we will never see, but about which we need to care.
—Carl Jung
Swiss Psychiatrist, 20th Century
In this section, we will explore what is meant by the concept of development and why the study of life-span development is important. We will outline the main characteristics of the life-span perspective and discuss various sources of contextual influences. In addition, we will examine some contemporary concerns in life-span development.
THE IMPORTANCE OF STUDYING LIFE-SPAN DEVELOPMENT
How might people benefit from examining life-span development? Perhaps you are, or will be, a parent or teacher. If so, responsibility for children is, or will be, a part of your everyday life. The more you learn about them, the better you can deal with them. Perhaps you hope to gain some insight about your own history—as an infant, a child, an adolescent, or a young adult. Perhaps you want to know more about what your life will be like as you grow through the adult years—as a middle-aged adult, or as an adult in old age, for example. Or perhaps you just stumbled onto this course, thinking that it sounded intriguing and that the study of the human life span might raise some provocative issues. Whatever your reasons for taking this course, you will discover that the study of life-span development is intriguing and filled with information about who we are, how we came to be this way, and where our future will take us.
Most development involves growth, but it also includes decline (as in dying). In exploring development, we will examine the life span from the point of conception until the time when life (or at least life as we know it) ends. You will see yourself as an infant, as a child, and as an adolescent, and be stimulated to think about how those years influenced the kind of individual you are today. And you will see yourself as a young adult, as a middle-aged adult, and as an adult in old age, and be motivated to think about how your experiences today will influence your development through the remainder of your adult years.Page 5
CHARACTERISTICS OF THE LIFE-SPAN PERSPECTIVE
Although growth and development are dramatic during the first two decades of life, development is not something that happens only to children and adolescents (Kennedy & Raz, 2015). The traditional approach to the study of development emphasizes extensive change from birth to adolescence (especially during infancy), little or no change in adulthood, and decline in old age. But a great deal of change does occur in the five or six decades after adolescence. The life-span approach emphasizes developmental change throughout adulthood as well as childhood (Park & Festini, 2018; Schaie & Willis, 2016).
Life Expectancy Recent increases in human life expectancy have contributed to the popularity of the life-span approach to development. The upper boundary of the human life span (based on the oldest age documented) is 122 years, as indicated in Figure 1; this maximum life span of humans has not changed since the beginning of recorded history. What has changed is life expectancy—the average number of years that a person born in a particular year can expect to live. In the twentieth century alone, life expectancy in the United States increased by 32 years, thanks to improvements in sanitation, nutrition, and medicine (see Figure 2). In 2016, the life expectancy in the United States was 79 years of age (U.S. Census Bureau, 2017). Today, for most individuals in developed countries, childhood and adolescence represent only about one-fourth of their lives.
FIGURE 1 MAXIMUM RECORDED LIFE SPAN FOR DIFFERENT SPECIES. Our only competitor for the maximum recorded life span is the Galápagos turtle.(Tortoise image on top) ©MedioImages/SuperStock; (mouse image at bottom) ©Redmond Durrell/AlamyFIGURE 2 HUMAN LIFE EXPECTANCY AT BIRTH FROM PREHISTORIC TO CONTEMPORARY TIMES. It took 5,000 years to extend human life expectancy from 18 to 41 years of age.
For the first time in U.S. history, there are more people over 60 years of age than under 15 years of age. In less than a century, more years were added to human life expectancy than in all of the prior millennia.
Laura Carstensen (2015, 2016) recently described the challenges and opportunities presented by this dramatic increase in life expectancy. In her view, the remarkable increase in the number of people living to an old age has happened so quickly that science, technology, and social expectations have not kept pace. She proposes that the challenge is to change from a world constructed mainly for young people to a world that is more compatible and supportive for the increasing number of people living to age 100 and beyond.
In further commentary, Carstensen (2015, p. 70) remarked that making this transformation would be no small feat:
. . . parks, transportation systems, staircases, and even hospitals presume that the users have both strength and stamina; suburbs across the country are built for two parents and their young children, not single people, multiple generations or elderly people who are not able to drive. Our education system serves the needs of young children and young adults and offers little more than recreation for experienced people.
Indeed, the very conception of work as a full-time endeavor ending in the early sixties is ill suited for long lives. Arguably the most troubling aspect of our view of aging is that we fret about ways the older people lack the qualities of younger people rather than exploit a growing new resource right before our eyes: citizens who have deep expertise, emotional balance, and the motivation to make a difference.
Certainly some progress has been made recently in improving the lives of older adults. In our discussion of late adulthood, you will read about progress in understanding and influencing the aging process through interventions such as modifying the activity of genes related to aging, improving brain function in the elderly, and slowing or even reversing the effects of various chronic diseases. You’ll also learn about ways to help people plan for a better life when they get old, become more cognitively sharp as they age, improve their physical fitness, and feel more satisfied with their lives as older adults. But much more remains to be accomplished, as suggested earlier by Laura Carstensen, as well as others (Bergeron, Ossenkoppele, & Laforce, 2018; Shrestha & others, 2018).
One-hundred-year-old Don Pellman from Santa Clara, California, keeps breaking world records in track for older adults, beating many contestants who are 20 and 30 years younger than he is.©Sandy Huffaker/The New York Times/Redux
The Life-Span Perspective The belief that development occurs throughout life is central to the life-span perspective on human development, but this perspective has other characteristics as well. According to life-span development expert Paul Baltes (1939–2006), the life-span perspective views development as lifelong, multidimensional, multidirectional, plastic, multidisciplinary, and contextual, and as a process that involves growth, maintenance, and regulation of loss (Baltes, 1987, 2003; Baltes, Lindenberger, & Staudinger, 2006). In Baltes’ Page 6view, it is important to understand that development is constructed through biological, sociocultural, and individual factors working together. Let’s explore each of these components of the life-span perspective.
Development Is Lifelong In the life-span perspective, early adulthood is not the endpoint of development; rather, no age period dominates development. Researchers increasingly study the experiences and psychological orientations of adults at different points in their lives. Later in this chapter, we will describe the age periods of development and their characteristics.
Development Is Multidimensional No matter what your age might be, your body, mind, emotions, and relationships are changing and affecting each other. Consider the development of Ted Kaczynski, the Unabomber discussed at the beginning of this chapter. When he was 6 months old, he was hospitalized with a severe allergic reaction and his parents were rarely allowed to visit him. According to his mother, the previously happy baby was never the same after his hospitalization. He became withdrawn and unresponsive. As Ted grew up, he had periodic “shutdowns” accompanied by rage. In his mother’s view, a biological event during infancy warped the development of her son’s mind and emotions.
Development has biological, cognitive, and socioemotional dimensions. Even within a dimension, there are many components (Dale & others, 2018; Moss & Wilson, 2018; Zammit & others, 2018). For example, attention, memory, abstract thinking, speed of processing information, and social intelligence are just a few of the components of the cognitive dimension.
Development Is Multidirectional Throughout life, some dimensions or components of a dimension expand and others shrink. For example, when one language (such as English) is acquired early in development, the capacity for acquiring second and third languages (such as Spanish and Chinese) decreases later in development, especially after early childhood (Levelt, 1989). During adolescence, as individuals establish romantic relationships, their time spent with friends may decrease. During late adulthood, older adults might become wiser because they have more experience than younger adults to draw upon to guide their decision making (Rakoczy & others, 2018; Thomas & others, 2018), but they perform more poorly on tasks that require speed in processing information (Salthouse, 2017).
Development Is Plastic Even at 10 years old, Ted Kaczynski was extraordinarily shy. Was he destined to remain forever uncomfortable with people? Developmentalists debate how much plasticity people have in various dimensions at different points in their development (Roisman & Cicchetti, 2017; Park & Festini, 2018). Plasticity means the capacity for change. For example, can you still improve your intellectual skills when you are in your seventies or eighties? Or might these intellectual skills be fixed by the time you are in your thirties so that further improvement is impossible? Researchers have found that the cognitive skills of older adults can be improved through training and acquisition of effective strategies (Motes & others, 2018; Shah & others, 2017). However, possibly we possess less capacity for change as we grow older (Shivarama Shetty & Sajikumar, 2017). Understanding plasticity and its constraints is a key element on the contemporary agenda for developmental research (Almy & Cicchetti, 2018; Park & Festini, 2018).
Paul Baltes, a leading architect of the life-span perspective of development, converses with one of the long-time research participants in the Berlin Aging Study that he directs. She joined the study in the early 1990s and has participated six times in extensive physical, medical, psychological, and social assessments. In her professional life, she was a physician.©Margaret M. and Paul B. Baltes Foundation
Developmental Science Is Multidisciplinary Psychologists, sociologists, anthropologists, neuroscientists, and medical researchers all share an interest in unlocking the mysteries of development through the life span. How do your heredity and health limit your intelligence? Do intelligence and social relationships change with age in the same ways around the world? How do families and schools influence intellectual development? These are examples of research questions that cut across disciplines.
Development Is Contextual All development occurs within a context, or setting. Contexts include families, schools, peer groups, churches, cities, neighborhoods, university laboratories, countries, and so on. Each of these settings is influenced by historical, economic, social, and cultural factors (Lubetkin & Jia, 2017; Nair, Roche, & White, 2018).
Contexts, like individuals, change (Taylor, Widaman, & Robins, 2018). Thus, individuals are changing beings in a changing world. As a result of these changes, contexts exert three types of influences (Baltes, 2003): (1) normative age-graded influences, (2) normative history-graded Page 7influences, and (3) nonnormative or highly individualized life events. Each type of influence can have a biological or environmental impact on development.
Normative age-graded influences are similar for individuals in a particular age group. These influences include biological processes such as puberty and menopause. They also include sociocultural factors and environmental processes such as beginning formal education (usually at about age 6 in most cultures) and retiring from the workforce (which takes place during the fifties and sixties in most cultures).
Normative history-graded influences are common to people of a particular generation because of historical circumstances (Ganguli, 2017; Heo & others, 2018). For example, during their youth American baby boomers shared the experience of the Cuban missile crisis, the assassination of John F. Kennedy, and the Beatles invasion. Other examples of normative history-graded influences include economic, political, and social upheavals such as the Great Depression in the 1930s, World War II in the 1940s, the civil rights and women’s rights movements of the 1960s and 1970s, the terrorist attacks of 9/11/2001, the integration of computers and cell phones into everyday life during the 1990s, and time spent on social media in the last decade (Schaie, 2016a, b; Tsai, Shillair, & Cotton, 2017). Long-term changes in the genetic and cultural makeup of a population (due to immigration or changes in fertility rates) are also part of normative historical change.
What characterizes the life-span perspective of development?©Derek E. Rothchild/Getty Images
Nonnormative life events are unusual occurrences that have a major impact on the lives of individual people. These events do not happen to everyone, and when they do occur they can influence people in different ways (Fredriksen-Goldsen & others, 2017; Jacobson & others, 2018; Shah & others, 2018). Examples include the death of a parent when a child is young, pregnancy in early adolescence, a fire that destroys a home, winning the lottery, or getting an unexpected career opportunity.
Nonnormative life events, such as Hurricane Sandy in 2012, are unusual circumstances that have a major impact on a person’s life.©Adam Hunger/Reuters/Landov
Development Involves Growth, Maintenance, and Regulation of Loss Baltes and his colleagues (2006) assert that the mastery of life often involves conflicts and competition among three goals of human development: growth, maintenance, and regulation of loss. As individuals age into middle and late adulthood, the maintenance and regulation of loss in their capacities takes center stage. Thus, a 75-year-old man might aim not to improve his memory or his golf swing but to maintain his independence and his ability to play golf at all. In the chapters on “Physical and Cognitive Development in Middle Adulthood” and “Socioemotional Development in Middle Adulthood” we will discuss these ideas about maintenance and regulation of loss in greater depth.
Development Is a Co-construction of Biology, Culture, and the Individual Development is a co-construction of biological, cultural, and individual factors working together (Baltes, Reuter-Lorenz, & Rösler, 2012). For example, the brain shapes culture, but it is also shaped by culture and the experiences that individuals have or pursue. In terms of individual factors, we can go beyond what our genetic inheritance and our environment give us. We can author a unique developmental path by actively choosing from the environment the things that optimize our lives (Rathunde & Csikszentmihalyi, 2006).
developmental connection
Middle Age
Adults typically face more losses in middle age than earlier in life. Connect to “Physical and Cognitive Development in Middle Adulthood.”
SOME CONTEMPORARY CONCERNS
Pick up a newspaper or magazine and you might see headlines like these: “Technology Shortens Toddlers’ Attention Spans,” “Political Leanings May Be Written in the Genes,” “Mother Accused of Tossing Children into Bay,” “Transgender Bathroom Laws Face Controversy,” “FDA Warns About Long-Term Effects of ADHD Drug,” “Heart Attack Deaths Higher in African American Patients,” or “Test May Predict Alzheimer Disease.” Researchers using the life-span perspective are examining these and many other topics of contemporary concern. The roles that health and well-being, parenting, education, sociocultural contexts, and technology play in life-span development, as well as how social policy is related to these issues, are a particular focus of this edition.
developmental connection
Exercise
What effect might exercise have on children’s and older adults’ ability to process information? Connect to “Physical and Cognitive Development in Middle and Late Childhood” and “Physical Development in Late Adulthood.”
Health and Well-Being Health professionals today recognize the powerful influences of lifestyles and psychological states on health and well-being (Hales, 2018; Rolfes, Pinna, & Whitney, 2018). In every chapter of Life-Span Development, issues of health and well-being are integrated into our discussions.
Clinical psychologists are among the health professionals who help people improve their well-being. Read about one clinical psychologist who helps adolescents and adults improve their developmental outcomes in Connecting with Careers.Page 8
connecting with careers
Gustavo Medrano, Clinical Psychologist
Gustavo Medrano specializes in helping children, adolescents, and adults of all ages improve their lives when they have problems involving depression, anxiety, emotion regulation, chronic health conditions, and life transitions. He works individually with clients and also provides therapy for couples and families. As a native Spanish speaker, he also provides bicultural and bilingual therapy for clients.
Gustavo Medrano, clinical psychologist, who does therapy with children, adolescents, and adults, especially using his bilingual background and skills to work with Latino clients.©Avis Mandel Pictures
Dr. Medrano is a faculty member at the Family Institute at Northwestern University in Evanston, Illinois. He obtained his undergraduate degree in psychology at Northwestern and then became a high school teacher through Teach for America, a program where participants spend at least two years teaching in a high-poverty area. He received his master’s and doctoral degrees in clinical psychology at the University of Wisconsin–Milwaukee. As a faculty member at Northwestern, in addition to doing clinical therapy with clients, he conducts research focusing on how family experiences, especially parenting, influence children’s and adolescents’ ability to cope with chronic pain and other challenges.
For more information about what clinical psychologists do, see the Careers in Life-Span Development appendix.
Parenting and Education Can two gay men raise a healthy family? Are children harmed if both parents work outside the home? Are U.S. schools failing to teach children how to read and write and calculate adequately? We hear many questions like these involving pressures on the contemporary family and conditions impairing the effectiveness of U.S. schools (Trejos-Castillo & Trevino-Schafer, 2018; Walsh, DeFlorio, & Burnham, 2017). In later chapters, we will analyze child care, the effects of divorce, parenting styles, child maltreatment, intergenerational relationships, early childhood education, links between childhood poverty and education, bilingual education, recent efforts to improve lifelong learning, and many other issues related to parenting and education (Gewirtz & Youssef, 2017; Morrison, 2018).
©Robert Maust/Photo Agora
Sociocultural Contexts and Diversity Health, parenting, and education—like development itself—are all shaped by their sociocultural context (Duncan, Magnuson, & Votruba-Drzal, 2017; Lansford & Banati, 2018). To analyze this context, four concepts are especially useful: culture, ethnicity, socioeconomic status, and gender.
Culture encompasses the behavior patterns, beliefs, and all other products of a particular group of people that are passed on from generation to generation (Kim & others, 2018). Culture results from the interaction of people over many years (Huo & Kim, 2018; Inglehart, 2018). A cultural group can be as large as the United States or as small as an isolated Appalachian town. Whatever its size, the group’s culture influences the behavior of its members (Erez, 2018; Matsumoto & Juang, 2017).Page 9
Cross-cultural studies compare aspects of two or more cultures. The comparison provides information about the degree to which development is similar (or universal) across cultures, or is instead culture-specific (Duell & others, 2018; Petersen & others, 2017; Wagner, 2018). For example, in a recent study of 26 countries, individuals in Chile had the highest life satisfaction, while those in Bulgaria and Spain had the lowest (Jang & others, 2017).
Ethnicity (the word ethnic comes from the Greek word for “nation”) is rooted in cultural heritage, nationality, race, religion, and language. African Americans, Latinos, Asian Americans, Native Americans, European Americans, and Arab Americans are a few examples of broad ethnic groups in the United States. Diversity exists within each ethnic group (Nieto & Bode, 2018; Suarez-Orozco, 2018a, b, c). A special concern is the discrimination and prejudice experienced by ethnic minority children (Brown, 2017; Motti-Stefanidi, 2018; Zeiders & others, 2018). Recent research indicates that pride in one’s ethnic identity group has positive outcomes (Umana-Taylor & Douglass, 2017; Umana-Taylor & others, 2018). For example, in a recent study, strong ethnic group affiliation and connection served a protective function in reducing risk for psychiatric problems (Anglin & others, 2018).
Asian American and Latino children are the fastest-growing immigrant groups in the United States. How diverse are the students in your life-span development class? How are their experiences in growing up likely similar to or different from yours?©Skip O’Rourke/Zuma Press Inc./Alamy
Socioeconomic status (SES) refers to a person’s position within society based on occupational, educational, and economic characteristics. Socioeconomic status implies certain inequalities (Duncan, Magnuson, & Votruba-Drzal, 2017; Loria & Caughy, 2018). Differences in the ability to control resources and to participate in society’s rewards produce unequal opportunities (Koller, Prates Santana, & Raffaelli, 2018; Singh & Mukherjee, 2018).
Gender refers to the characteristics of people as males and females. Few aspects of our development are more central to our identity and social relationships than gender (Dettori & Gupta, 2018; Ellemers, 2018; Liben, 2017).
Recently, considerable interest has been generated about a category of gender classification, transgender, a broad term that refers to individuals who adopt a gender identity that differs from the one assigned to them at birth (Budge & Orovecz, 2018; Savin-Williams, 2017). For example, individuals may have a female body but identify more strongly with being masculine than feminine, or have a male body but identify more strongly with being feminine than masculine. A transgender identity of being born male but identifying with being a female is much more common than the reverse (Zucker, Lawrence, & Kreukels, 2016). We will have much more to say about gender and transgender later in the text.
In the United States, the sociocultural context has become increasingly diverse in recent years. The U.S. population includes a greater variety of cultures and ethnic groups than ever before. This changing demographic tapestry promises not only the richness that diversity brings but also difficult challenges in extending the American dream to all individuals (Cano & others, 2017; Nieto & Bode, 2018). We will discuss sociocultural contexts and diversity in each chapter.
A special cross-cultural concern is the educational and psychological conditions of women around the world (UNICEF, 2017, 2018). Inadequate educational opportunities, violence, and mental health issues are among the problems faced by many women.
Considerable progress has been made in many parts of the world in girls’ school attendance (UNICEF, 2017). However, in some regions, girls continue to receive less education. For example, in secondary schools in West and Central Africa, only 76 girls are enrolled for every 100 boys (UNICEF, 2015).
Doly Akter, age 17, lives in a slum in Dhaka, Bangladesh, where sewers overflow, garbage rots in the streets, and children are undernourished. Nearly two-thirds of young women in Bangladesh marry before they are 18. Doly organized a club supported by UNICEF in which girls go door-to-door to monitor the hygiene habits of households in their neighborhood. The monitoring has led to improved hygiene and health in the families. Also, her group has managed to stop several child marriages by meeting with parents and convincing them that it is not in their daughter’s best interests. When talking with parents in their neighborhoods, the girls in the club emphasize the importance of staying in school and how this will improve their daughters’ future. Doly says that the girls in her UNICEF group are far more aware of their rights than their mothers ever were. (UNICEF, 2007).Courtesy of Naser Siddique/UNICEF Bangladesh
Social Policy Social policy is a government’s course of action designed to promote the welfare of its citizens. Values, economics, and politics all shape a nation’s social policy (Lansford & Banati, 2018; Ruck, Peterson-Badali, & Freeman, 2017). Out of concern that policy makers are doing too little to protect the well-being of children and older adults, life-span researchers are increasingly undertaking studies that they hope will lead to effective social policy (Lerner & others, 2018; McQueen, 2017).
Statistics such as infant mortality rates, mortality among children under 5, and the percentage of children who are malnourished or living in poverty provide benchmarks for evaluating how well children are doing in a particular society (UNICEF, 2017, 2018). Marian Wright Edelman, a tireless advocate for children’s rights, has pointed out that such indicators place the United States at or near the lowest rank for industrialized nations in the treatment of children.
Children who grow up in poverty represent a special concern (Duncan, Magnuson, & Votruba-Drzal, 2017; Suarez-Orozco, 2018a, b, c). In 2015, 19.7 percent of U.S. children under 18 years of age were living in families with incomes below the poverty line, with African American (36 percent) and Latino (30 percent) families with children having especially high rates of Page 10poverty (Jiang, Granja, & Koball, 2017). In 2015, 12 percent of non-Latino White children were living in poverty. Compared with non-Latino White children, ethnic minority children are more likely to experience persistent poverty over many years and live in isolated poor neighborhoods where social supports are minimal and threats to positive development are abundant.
Marian Wright Edelman, president of the Children’s Defense Fund (shown here advocating for health care), has been a tireless advocate of children’s rights and has been instrumental in calling attention to the needs of children. What are some of these needs?Courtesy of the Children’s Defense Fund and Marian Wright Edelman
The overall poverty rate for U.S. children did drop from 21.2 percent in 2014 to 19.7 percent in 2015 (Proctor, Semega, & Kollar, 2016). The 19.7 percent figure represents an increase from 2001 (14.5 percent) but reflects a slight drop from a peak of 23 percent in 1993.The U.S. figure of 19.7 percent of children living in poverty is much higher than the rates in other developed countries. For example, Canada has a child poverty rate of 9 percent and Sweden has a rate of 2 percent.
Ann Masten (far right) with a homeless mother and her child who are participating in her research on resilience. Masten and her colleagues have found that good parenting skills and good cognitive skills (especially attention and self-control) increase the likelihood that children in challenging circumstances will do well in elementary school.©Dawn Villella Photography
As indicated in Figure 3, one study found that a higher percentage of U.S. children in poor families than in middle-income families were exposed to family turmoil, separation from a parent, violence, crowding, excessive noise, and poor housing (Evans & English, 2002). One study also revealed that the more years children spent living in poverty, the higher were their physiological indices of stress (Evans & Kim, 2007).
FIGURE 3 EXPOSURE TO SIX STRESSORS AMONG POOR AND MIDDLE-INCOME CHILDREN. One study analyzed the exposure to six stressors among poor children and middle-income children (Evans & English, 2002). Poor children were much more likely to face each of these stressors.
Edelman says that parenting and nurturing the next generation of children is our society’s most important function and that we need to take it more seriously than we have in the past. To read about efforts to improve the lives of children through social policies, see Connecting Development to Life.
Some children triumph over poverty or other adversities. They show resilience (Masten, 2015, 2017). Think back to the chapter-opening story about Alice Walker. In spite of racism, poverty, low socioeconomic status, and a disfiguring eye injury, she went on to become a successful author and champion for equality.
Are there certain characteristics that make children like Alice Walker resilient? Are there other characteristics that influence the development of children like Ted Kaczynski, who, despite his intelligence and education, became a killer? After analyzing research on this topic, Ann Masten and her colleagues (Masten, 2006, 2009, 2011, 2013, 2014, 2015, 2016, 2017; Masten, Burt, & Coatsworth, 2006; Masten & Kalstabakken, 2018) concluded that a number of individual factors, such as good intellectual functioning, influence resiliency. In addition, as Figure 4 shows, the families and extrafamilial contexts of resilient individuals tend to share certain features. For example, resilient children are likely to have a close relationship with a caring parent figure and bonds to caring adults outside the family.
FIGURE 4 CHARACTERISTICS OF RESILIENT CHILDREN AND THEIR CONTEXTS
At the other end of the life span, the well-being of older adults also creates policy issues (Burns, Browning, and Kendig, 2017; Jennifer, 2018; Volkwein-Caplan & Tahmaseb-McConatha, 2018). Key concerns are escalating health care costs and the access of older adults to adequate health care (Cunningham, Green, & Braun, 2018; Kane, Saliba, & Hollmann, 2017). One study found that the U.S. health care system fails older adults in many areas (Wenger & others, 2003). For example, older adults received the recommended care for general medical conditions such as heart disease only 52 percent of the time; they received appropriate care for undernutrition and Alzheimer disease only 31 percent of the time.Page 11
connecting development to life
Improving Family Policy
In the United States, the actions of the national government, state governments, and city governments influence the well-being of children (Gottlieb & DeLoache, 2017; Lerner & others, 2018). When families seriously endanger a child’s well-being, governments often step in to help. At the national and state levels, policy makers have debated for decades about whether helping poor parents ends up helping their children as well. Researchers are providing some answers by examining the effects of specific policies (Duncan, Magnuson, & Vrtoba-Drzal, 2017).
For example, the Minnesota Family Investment Program (MFIP) was designed in the 1990s primarily to influence the behavior of adults—specifically, to move adults off the welfare rolls and into paid employment. A key element of the program was its guarantee that adults participating in the program would receive more income if they worked than if they did not. When the adults’ income rose, how did that affect their children? A study of the effects of MFIP found that increased incomes of working poor parents were linked with benefits for their children (Gennetian & Miller, 2002). The children’s achievement in school improved, and their behavior problems decreased. A current MFIP study is examining the influence of providing specific services to low-income families at risk for child maltreatment and other negative outcomes for children (Minnesota Family Investment Program, 2009).
There is increasing interest in developing two-generation educational interventions to improve the academic success of children living in poverty (Gardner, Brooks-Gunn, & Chase-Lansdale, 2016; Sommer & others, 2016). For example, a recent large-scale effort to help children escape from poverty is the Ascend two-generation education intervention being conducted by the Aspen Institute (2013, 2018; King, Chase-Lansdale, & Small, 2015). The focus of the intervention emphasizes education (increasing postsecondary education for mothers and improving the quality of their children’s early childhood education), economic support (housing, transportation, financial education, health insurance, and food assistance), and social capital (peer support including friends and neighbors; participation in community and faith-based organizations; school and work contacts).
Developmental psychologists and other researchers have examined the effects of many other government policies. They are seeking ways to help families living in poverty improve their well-being, and they have offered many suggestions for improving government policies (Lansford & Banati, 2018; McQueen, 2017; Motti-Stefanidi, 2018; Yoshikawa & others, 2017).
Earlier, we learned that children who live in poverty experience higher levels of physiological stress. How might a child’s stress level be affected by the implementation of MFIP?
These concerns about the well-being of older adults are heightened by two facts. First, the number of older adults in the United States is growing dramatically, as Figure 5 shows. Second, many of these older Americans are likely to need society’s help (Conway & others, 2018; Simon, Soni, & Cawley, 2017). Not only is the population of older adults growing in the United States, but the world’s population of people 60 years and older is projected to increase from 900 million in 2015 to 2.1 billion in 2050 (United Nations, 2015). The world’s population of those 80 years and older is expected to triple or quadruple in this time frame.
FIGURE 5 THE AGING OF AMERICA. The number of Americans over age 65 has grown dramatically since 1900 and is projected to increase further from the present to the year 2040. A significant increase will also occur in the number of individuals in the 85-and-over group. Centenarians—persons 100 years of age or older—are the fastest-growing age group in the United States, and their numbers are expected to swell in the coming decades.
Compared with adults in earlier decades, U.S. adults today are less likely to be married, more likely to be childless, and more likely to be living alone (Poey, Burr, & Roberts, 2017). As the older population continues to expand during the twenty-first century, an increasing number of older adults will be without either a spouse or children—traditionally the main sources of support for older adults. These individuals will need social relationships, networks, and other forms of support (Andrew & Meeks, 2018; Shankar & others, 2017).Page 12
Technology A final discussion in our exploration of contemporary topics is the recent dramatic, almost overwhelming increase in the use of technology at all points in human development (Lever-Duffy & McDonald, 2018; Vernon, Modecki, & Barber, 2018). From the introduction of television in the mid ’50s, to the replacement of typewriters with computers that can do far more than just print words, and later to the remarkable invention of the Internet and the proliferation of smartphones, followed by the pervasiveness of social media and the development of robots that can do some jobs better than humans can, our way of life has been changed permanently by technological advances.
How might the infusion of technology into children’s, adolescents’, and adults’ lives be changing the way they function and learn?©DaydreamsGirl/Getty Images
We will explore many technology topics in this edition. Later in this chapter you will read about the emerging field of developmental robotics in our discussion of information processing, and you will ponder the influence of technology on generations such as the millennials. Other topics we will explore include whether babies should watch television and videos, with special attention to potential effects of audiovisual media on language development; indications that too much screen time reduces children’s participation in physical activities and increases their risk for obesity and cardiovascular disease; the effects on learning when many adolescents spend more time using various media than they do in school and the question of whether multitasking with various electronic devices is harmful or beneficial; as well as the degree to which older adults are adapting to the extensive role of technology in their lives, especially since they grew up without so much technology.
Review Connect Reflect
LG1 Discuss the distinctive features of a life-span perspective on development.
Review
- What is meant by the concept of development? Why is the study of life-span development important?
- What are the main characteristics of the life-span perspective? What are three sources of contextual influences?
- What are some contemporary concerns in life-span development?
Connect
- Give your own example (not found in this chapter) of how biology, culture, and individual experience interact to affect development.
Reflect Your Own Personal Journey of Life
- Imagine what your development would have been like in a culture that offered fewer or distinctly different choices. How might your development have been different if your family had been significantly richer or poorer?
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2 The Nature of Development
LG2 Identify the most important processes, periods, and issues in development.
Biological, Cognitive, and Socioemotional Processes
Periods of Development
The Significance of Age
Developmental Issues
In this section, we will explore what is meant by developmental processes and periods, as well as variations in the way age is conceptualized. We will examine key developmental issues and strategies we can use to evaluate them.
If you wanted to describe how and why Alice Walker or Ted Kaczynski developed during their lifetimes, how would you go about it? A chronicle of the events in any person’s life can quickly become a confusing and tedious array of details. Two concepts help provide a framework for describing and understanding an individual’s development: developmental processes and periods.
BIOLOGICAL, COGNITIVE, AND SOCIOEMOTIONAL PROCESSES
At the beginning of this chapter, we defined development as the pattern of change that begins at conception and continues through the life span. The pattern is complex because it is the product of biological, cognitive, and socioemotional processes (see Figure 6).
FIGURE 6 PROCESSES INVOLVED IN DEVELOPMENTAL CHANGES. Biological, cognitive, and socioemotional processes interact as individuals develop.
Biological Processes Biological processes produce changes in an individual’s physical nature. Genes inherited from parents, brain development, height and weight gains, changes in motor skills, nutrition, exercise, the hormonal changes of puberty, and cardiovascular decline are all examples of biological processes that affect development. Especially in recent years with the advent of new techniques to study people’s actual genetic makeup, there has been a substantial increase in studies that focus on the role of genes in development at different points in the life span (Amare & others, 2017; Bardak & others, 2018). Likewise, with the invention of brain-imaging techniques such as magnetic resonance imaging, there has been an explosion of research on how the brain influences many aspects of development at different points in the life span (Bell & others, 2018; Park & Festini, 2018).
Cognitive Processes Cognitive processes refer to changes in the individual’s thought, intelligence, and language. Watching a colorful mobile swinging above the crib, putting together a two-word sentence, memorizing a poem, imagining what it would be like to be a movie star, and solving a crossword puzzle all involve cognitive processes.
Socioemotional Processes Socioemotional processes involve changes in the individual’s relationships with other people, changes in emotions, and changes in personality. An infant’s smile in response to a parent’s touch, a toddler’s aggressive attack on a playmate, a school-age child’s development of assertiveness, an adolescent’s joy at the senior prom, and the affection of an elderly couple all reflect the role of socioemotional processes in development.
developmental connection
Brain Development
Is there a link between changes in the adolescent’s brain and their mood swings and increased risk taking? Connect to “Physical and Cognitive Development in Adolescence.”
Connecting Biological, Cognitive, and Socioemotional Processes Biological, cognitive, and socioemotional processes are inextricably intertwined (Diamond, 2013). Consider a baby smiling in response to a parent’s touch. This response depends on biological processes (the physical nature of touch and responsiveness to it), cognitive processes (the ability to understand intentional acts), and socioemotional processes (the fact that smiling often reflects a positive emotional feeling and helps to connect us in positive ways with other human beings). Nowhere is the connection across biological, cognitive, and socioemotional processes more obvious than in two rapidly emerging fields:
- developmental cognitive neuroscience, which explores links between development, cognitive processes, and the brain (Bell & others, 2018; Nyberg, Pudas, & Lundquist, 2017).
- developmental social neuroscience, which examines connections between socioemotional processes, development, and the brain (Silvers & others, 2017; Sullivan & Wilson, 2018).
Page 14In many instances, biological, cognitive, and socioemotional processes are bidirectional. For example, biological processes can influence cognitive processes and vice versa. Thus, although usually we will study the different processes of development (biological, cognitive, and socioemotional) separately, keep in mind that we are talking about the development of an integrated individual with a mind and body that are interdependent. In many places throughout the book, we will call attention to these connections.
PERIODS OF DEVELOPMENT
The interplay of biological, cognitive, and socioemotional processes produces the periods of the human life span (see Figure 7). A developmental period refers to a time frame in a person’s life that is characterized by certain features. For the purposes of organization and understanding, we commonly describe development in terms of these periods. The most widely used classification of developmental periods involves the eight-period sequence shown in Figure 7. Approximate age ranges are listed for the periods to provide a general idea of when each period begins and ends.
FIGURE 7 PROCESSES AND PERIODS OF DEVELOPMENT. The unfolding of life’s periods of development is influenced by the interaction of biological, cognitive, and socioemotional processes.(Photo credit left to right) ©Brand X Pictures/PunchStock; Courtesy of Dr. John Santrock; ©Laurence Mouton/Photoalto/PictureQuest; ©Digital Vision/Getty Images; ©SW Productions/Getty Images; ©Blue Moon Stock/Alamy Images; ©Sam Edwards/Glow Images; ©Ronnie Kaufman/Blend Images LLC
The prenatal period is the time from conception to birth. It involves tremendous growth—from a single cell to an organism complete with brain and behavioral capabilities—and takes place in approximately a 9-month period.
Infancy is the developmental period from birth to 18 or 24 months. Infancy is a time of extreme dependence upon adults. During this period, many psychological activities—language, symbolic thought, sensorimotor coordination, and social learning, for example—are just beginning.
The term toddler is often used to describe a child from about 1 ½ to 3 years of age. Toddlers are in a transitional period between infancy and the next period, early childhood.
Early childhood is the developmental period from 3 through 5 years of age. This period is sometimes called the “preschool years.” During this time, young children learn to become more self-sufficient and to care for themselves, develop school readiness skills (following instructions, identifying letters), and spend many hours playing with peers. First grade typically marks the end of early childhood.
Middle and late childhood is the developmental period from about 6 to 10 or 11 years of age, approximately corresponding to the elementary school years. During this period, children Page 15master the fundamental skills of reading, writing, and arithmetic, and they are formally exposed to the larger world and its culture. Achievement becomes a more central theme of the child’s world, and self-control increases.
Adolescence is the developmental period of transition from childhood to early adulthood, entered at approximately 10 to 12 years of age and ending at 18 to 21 years of age. Adolescence begins with rapid physical changes—dramatic gains in height and weight, changes in body contour, and the development of sexual characteristics such as enlargement of the breasts, growth of pubic and facial hair, and deepening of the voice. At this point in development, the pursuit of independence and an identity are preeminent. Thought is more logical, abstract, and idealistic. More time is spent outside the family.
There has been a substantial increase in interest in the transition between adolescence and early adulthood, a transition that can be a long one as individuals develop more effective skills to become full members of society. Recently, the transition from adolescence to adulthood has been referred to as emerging adulthood, the period from approximately 18 to 25 years of age (Arnett, 2015, 2016a, b). Experimentation and exploration characterize the emerging adult. At this point in their development, many individuals are still exploring which career path they want to follow, what they want their identity to be, and which lifestyle they want to adopt (for example, single, cohabiting, or married) (Jensen, 2018; Padilla-Walker & Nelson, 2017).
Early adulthood is the developmental period that begins in the early twenties and lasts through the thirties. It is a time of establishing personal and economic independence, advancing in a career, and for many, selecting a mate, learning to live with that person in an intimate way, starting a family, and rearing children.
Middle adulthood is the developmental period from approximately 40 to about 60 years of age. It is a time of expanding personal and social involvement and responsibility; of assisting the next generation in becoming competent, mature individuals; and of reaching and maintaining satisfaction in a career.
Late adulthood is the developmental period that begins during the sixties or seventies and lasts until death. It is a time of life review, retirement, and adjustment to new social roles and diminishing strength and health.
One’s children’s children’s children. Look back to us as we look to you; we are related by our imaginations. If we are able to touch, it is because we have imagined each other’s existence, our dreams running back and forth along a cable from age to age.
—Roger Rosenblatt
Contemporary American Writer
Late adulthood has the longest span of any period of development, and as noted earlier, the number of people in this age group has been increasing dramatically. As a result, life-span developmentalists have been paying more attention to late adulthood (Bangerter & others, 2018; Frankenmolen & others, 2018; Orkaby & others, 2018). Paul Baltes and Jacqui Smith (2003) argue that a major change takes place in older adults’ lives as they become the “oldest-old,” on average at about 85 years of age. For example, the “young-old” (classified as 65 through 84 in this analysis) have substantial potential for physical and cognitive fitness, retain much of their cognitive capacity, and can develop strategies to cope with the gains and losses of aging. In contrast, the oldest-old (85 and older) show considerable loss in cognitive skills, experience an increase in chronic stress, and become more frail.
Thus, Baltes and Smith concluded that considerable plasticity and adaptability characterize adults from their sixties until their mid-eighties but that the oldest-old have reached the limits of their functional capacity, which makes interventions to improve their lives difficult. Nonetheless, as will be described in later chapters, considerable variation exists in the degree to which the oldest-old retain their capabilities (Mejia & others, 2017).
Four Ages Life-span developmentalists who focus on adult development and aging increasingly describe life-span development in terms of four “ages” (Baltes, 2006; Willis & Schaie, 2006):
- First age: Childhood and adolescence
- Second age: Prime adulthood, ages 20 through 59
- Third age: Approximately 60 to 79 years of age
- Fourth age: Approximately 80 years and older
The major emphasis in this conceptualization is on the third and fourth ages, especially the increasing evidence that individuals in the third age are healthier and can lead more active, productive lives than their predecessors in earlier generations. However, when older adults reach their eighties (fourth age), especially 85 and over, health and well-being decline for many individuals.Page 16
Three Developmental Patterns of Aging K. Warner Schaie (2016a, b) recently described three different developmental patterns that provide a portrait of how aging can encompass individual variations:
- Normal aging characterizes most individuals, for whom psychological functioning often peaks in early middle age, remains relatively stable until the late fifties to early sixties, and then shows a modest decline through the early eighties. However, marked decline can occur as individuals approach death.
- Pathological aging characterizes individuals who show greater than average decline as they age through the adult years. In early old age, they may have mild cognitive impairment, develop Alzheimer disease later on, or have a chronic disease that impairs their daily functioning.
- Successful aging characterizes individuals whose positive physical, cognitive, and socioemotional development is maintained longer, declining later in old age than is the case for most people. For too long, only the declines that occur in late adulthood were highlighted, but recently there has been increased interest in the concept of successful aging (Docking & Stock, 2018).
Connections Across Periods of Development A final important point needs to be made about the periods of the human life span. Just as there are many connections between biological, cognitive, and socioemotional processes, so are there many connections between the periods of the human life span. A key element in the study of life-span development is how development in one period is connected to development in another period. For example, when individuals reach adolescence, many developments and experiences have already taken place in their lives. If an adolescent girl becomes depressed, might her depression be linked to development early in her life, as well as recent and current development? Throughout the text we will call attention to such connections across periods of development through Developmental Connection inserts that guide you to earlier or later connections with the material you are currently reading.
THE SIGNIFICANCE OF AGE
In our description of developmental periods, we linked an approximate age range with each period. But we also have noted that there are variations in the capabilities of individuals of the same age, and we have seen how age-related changes can be exaggerated. How important is age in understanding the characteristics of an individual?
Age and Happiness Is there a best age to be? An increasing number of studies indicate that in the United States adults are happier as they age. Consider also a U.S. study of approximately 28,000 individuals from 18 to 88 that revealed happiness increased with age (Yang, 2008). About 33 percent were very happy at 88 years of age compared with only about 24 percent in their late teens and early twenties. Why might older people report being happier and more satisfied with their lives than younger people? Despite facing higher incidences of physical problems and losses, older adults are more content with what they have in their lives, have better relationships with the people who matter to them, are less pressured to achieve, have more time for leisurely pursuits, and have many years of experience resulting in wisdom that may help them adapt better to their circumstances than younger adults do (Carstensen, 2015; Sims, Hogan, & Carstensen, 2015). Researchers have also found that baby boomers (those born between 1946 and 1964) tend to report being less happy than individuals born earlier—possibly because they are not lowering their aspirations and idealistic hopes as they age, as did earlier generations. Because growing older is a certain outcome of staying alive, it is good to know that we are likely to be happier as older adults than we were when we were younger.
Which of these individuals is likely to be the happiest and to report the highest level of psychological well-being?©Jetta Productions/Blend Images/Getty Images
Page 17Not all studies, though, have found an increase in life satisfaction with age (Steptoe, Deaton, & Stone, 2015). Some studies indicate that the lowest levels of life satisfaction occur in middle age, especially from 45 to 54 years of age (OECD, 2014). Other studies have found that life satisfaction varies across some countries. For example, respondents in research studies conducted in the former Soviet Union and Eastern Europe, as well as in South American countries, reported a decrease in life satisfaction with advancing age (Deaton, 2008). Further, older adults in poor health, such as those with cardiovascular disease, chronic lung disease, and depression, tend to be less satisfied with their lives than their healthier older adult counterparts (Lamont & others, 2017).
Now that you have read about age variations in life satisfaction, think about how satisfied you are with your life. To help you answer this question, complete the items in Figure 8, which presents the most widely used measure in research on life satisfaction (Diener, 2018).
FIGURE 8 HOW SATISFIED AM I WITH MY LIFE?Source: E. Diener, R. A. Emmons, R. J. Larson, & S. Griffin. “The Satisfaction with Life Scale.” Journal of Personality Assessment, 48, 1985, 71–75.
Conceptions of Age According to some life-span experts, chronological age is not very relevant to understanding a person’s psychological development (Botwinick, 1978). Chronological age is the number of years that have elapsed since birth. But time is a crude index of experience, and it does not cause anything. Chronological age, moreover, is not the only way to measure age (MacDonald & Stawski, 2016). Just as there are different domains of development, there are different ways of thinking about age.
Age has been conceptualized not just as chronological age but also as biological age, psychological age, and social age (Hoyer & Roodin, 2009). Biological age is a person’s age in terms of biological health. Determining biological age involves knowing the functional capacities of a person’s vital organs. One person’s vital capacities may be better or worse than those of other people of comparable age (Richards & others, 2015). A recent study of 17-year survival rates in Korean adults 20 to 93 years of age found that when biological age was greater than chronological age individuals were less likely to have died (Yoo & others, 2017). The younger the person’s biological age, the longer the person is expected to live, regardless of chronological age.
(Left): Seventy-four year old Barbara Jordan participating in the long jump competition at a Senior Games in Maine; (right): a sedentary overweight middle-aged man. Even though Barbara Jordan’s chronological age is older, might her biological age be younger than the middle-aged man’s?(left) ©John Patriquin/Portland Press Herald/Getty Images; (right) ©Owaki-Kulla/Corbis/Getty Images
Page 18Psychological age is an individual’s adaptive capacities compared with those of other individuals of the same chronological age. Thus, older adults who continue to learn, are flexible, are motivated, have positive personality traits, control their emotions, and think clearly are engaging in more adaptive behaviors than their chronological age-mates who do not continue to learn, are rigid, are unmotivated, do not control their emotions, and do not think clearly (Rakoczy & others, 2018; Thomas & others, 2018). A longitudinal study of more than 1,200 individuals across seven decades revealed that the personality trait of conscientiousness (being organized, careful, and disciplined, for example) predicted lower mortality (frequency of death) risk from childhood through late adulthood (Martin, Friedman, & Schwartz, 2007). And a recent study found that a higher level of conscientiousness was protective of cognitive functioning in older adults (Wilson & others, 2015).
How old would you be if you didn’t know how old you were?
—Satchel Paige
American Baseball Pitcher, 20th Century
Social age refers to connectedness with others and the social roles individuals adopt. Individuals who have better social relationships with others are happier and more likely to live longer than individuals who are lonely (Carstensen & others, 2015; Reed & Carstensen, 2015).
Life-span expert Bernice Neugarten (1988) argues that in U.S. society chronological age is becoming irrelevant. The 28-year-old mayor, the 35-year-old grandmother, the 65-year-old father of a preschooler, the 55-year-old widow who starts a business, and the 70-year-old student illustrate that old assumptions about the proper timing of life events no longer govern our lives. We still have some expectations for when certain life events—such as getting married, having children, and retiring—should occur. However, chronological age has become a less accurate predictor of these life events in our society. Moreover, issues such as how to deal with intimacy and how to cope with success and failure appear and reappear throughout the life span.
From a life-span perspective, an overall age profile of an individual involves not just chronological age but also biological age, psychological age, and social age. For example, a 70-year-old man (chronological age) might be in good physical health (biological age), be experiencing memory problems and not be coping well with the demands placed on him by his wife’s recent hospitalization (psychological age), and have a number of friends with whom he regularly plays golf (social age).
developmental connection
Nature and Nurture
Can specific genes be linked to specific environmental experiences to influence development? Connect to “Biological Beginnings.”
DEVELOPMENTAL ISSUES
Was Ted Kaczynski born a killer, or did his life turn him into one? Kaczynski himself thought that his childhood was the root of his troubles, saying that he grew up as a genius in a boy’s body and never fit in with other children. Did his early experiences determine his later life? Is your own journey through life marked out ahead of time, or can your experiences change your path? Are the experiences you have early in your journey more important than later ones? Is your journey more like taking an elevator up a skyscraper with distinct stops along the way or more like a cruise down a river with smoother ebbs and flows? These questions point to three issues about the nature of development: the roles played by nature and nurture, stability and change, and continuity and discontinuity.
developmental connection
Personality
How much does personality change as people go through the adult years? Connect to “Socioemotional Development in Middle Adulthood.”
What are some key developmental issues?©Rubberball/PictureQuest
Nature and Nurture The nature-nurture issue involves the extent to which development is influenced by nature and by nurture. Nature refers to an organism’s biological inheritance, nurture to its environmental experiences.
According to those who emphasize the role of nature, just as a sunflower grows in an orderly way—unless flattened by an unfriendly environment—so too the human grows in an orderly way. An evolutionary and genetic foundation produces commonalities in growth and development (Freedman, 2017; Starr, Evers, & Starr, 2018). We walk before we talk, speak one word before two words, grow rapidly in infancy and less so in early childhood, experience a rush of sex hormones in puberty, reach the peak of our physical strength in late adolescence and early adulthood, and then physically decline. Proponents of the importance of nature acknowledge that extreme environments—those that are psychologically barren or hostile—can depress development. However, they believe that basic growth tendencies are genetically programmed into humans (Johnson, 2017).
By contrast, other psychologists emphasize the importance of nurture, or environmental experiences, in development (Almy & Cicchetti, 2018; Nicolaisen & Thorsen, 2017; Rubin & Barstead, 2018). Experiences run the gamut from the individual’s biological environment Page 19(nutrition, medical care, drugs, and physical accidents) to the social environment (family, peers, schools, community, media, and culture).
There has been a dramatic increase in the number of studies that reflect the epigenetic view, which states that development reflects an ongoing, bidirectional interchange between genes and the environment. These studies involve specific DNA sequences (Bakusic & others, 2017; Halldorsdottir & Binder, 2017). The epigenetic mechanisms involve the actual molecular modification of the DNA strand as a result of environmental inputs in ways that alter gene functioning (Moore, 2017; Clukay & others, 2018; Marzi & others, 2018). In “Biological Beginnings” we will explore the epigenetic approach in greater depth.
Stability and Change Is the shy child who hides behind the sofa when visitors arrive destined to become a wallflower at college dances, or might the child become a sociable, talkative individual? Is the fun-loving, carefree adolescent bound to have difficulty holding down a 9-to-5 job as an adult? These questions reflect the stability-change issue, which involves the degree to which early traits and characteristics persist through life or change.
Many developmentalists who emphasize stability in development argue that stability is the result of heredity and possibly early experiences in life. For example, many argue that if an individual is shy throughout life (as Ted Kaczynski was), this stability is due to heredity and possibly early experiences in which the infant or young child encountered considerable stress when interacting with people.
Developmentalists who emphasize change take the more optimistic view that later experiences can produce change. Recall that in the life-span perspective, plasticity, the potential for change, exists throughout the life span, although possibly to different degrees (Park & Festini, 2018; Motes & others, 2018). Experts such as Paul Baltes (2003) argue that older adults often show less capacity for learning new things than younger adults do. However, many older adults continue to be good at practicing what they have learned earlier in life.
The roles of early and later experience are an aspect of the stability-change issue that has long been hotly debated (Chen & others, 2018; Roisman & Cicchetti, 2017). Some argue that warm, nurturant caregiving during infancy and toddlerhood predicts optimal development later in life (Cassidy, 2016). The later-experience advocates see children as malleable throughout development and believe later sensitive caregiving is just as important as earlier sensitive caregiving (Joling & others, 2018; Taylor & others, 2018).
Continuity and Discontinuity When developmental change occurs, is it gradual or abrupt? Think about your own development for a moment. Did you gradually become the person you are today? Or did you experience sudden, distinct changes as you matured? For the most part, developmentalists who emphasize nurture describe development as a gradual, continuous process. Those who emphasize nature often describe development as a series of distinct stages.
The continuity-discontinuity issue focuses on the degree to which development involves either gradual, cumulative change (continuity) or distinct stages (discontinuity). In terms of continuity, as the oak grows from seedling to giant oak, it becomes more of an oak—its development is continuous (see Figure 9). Similarly, a child’s first word, though seemingly an abrupt, discontinuous event, is actually the result of weeks and months of growth and practice. Puberty might seem abrupt, but it is a gradual process that occurs over several years.
FIGURE 9 CONTINUITY AND DISCONTINUITY IN DEVELOPMENT. Is our development like that of a seedling gradually growing into a giant oak? Or is it more like that of a caterpillar suddenly becoming a butterfly?
In terms of discontinuity, as an insect grows from a caterpillar to a chrysalis to a butterfly, it passes through a sequence of stages in which change is qualitatively rather than quantitatively different. Similarly, at some point a child moves from not being able to think abstractly about the world to being able to do so. This is a qualitative, discontinuous change in development rather than a quantitative, continuous change.
Evaluating the Developmental Issues Most life-span developmentalists acknowledge that development is not all nature or all nurture, not all stability or all change, and not all continuity or all discontinuity. Nature and nurture, stability and change, continuity and discontinuity characterize development throughout the human life span.
Although most developmentalists do not take extreme positions on these three important issues, there is spirited debate regarding how strongly development is influenced by each of these factors (Almy & Cicchetti, 2018; Moore, 2017).
Page 20
Review Connect Reflect
LG2 Identify the most important processes, periods, and issues in development.
Review
- What are three key developmental processes?
- What are eight main developmental periods?
- How is age related to development?
- What are three main developmental issues?
Connect
- In the previous section, we discussed biological, cognitive, and socioemotional processes. What concepts do these processes have in common with the issue of nature versus nurture, which was also discussed in this section?
Reflect Your Own Personal Journey of Life
- Do you think there was/is/will be a best age for you to be? If so, what is it? Why?
3 Theories of Development
LG3 Describe the main theories of human development.
Psychoanalytic Theories
Cognitive Theories
Behavioral and Social Cognitive Theories
Ethological Theory
Ecological Theory
An Eclectic Theoretical Orientation
How can we answer questions about the roles of nature and nurture, stability and change, and continuity and discontinuity in development? How can we determine, for example, whether deterioration of memory in older adults can be prevented or whether special care can repair the harm inflicted by child neglect? The scientific method is the best tool we have to answer such questions (Smith & Davis, 2016).
There is nothing quite so practical as a good theory.
—Kurt Lewin
American Social Psychologist, 20th Century
The scientific method is essentially a four-step process: (1) conceptualize a process or problem to be studied, (2) collect research information (data), (3) analyze the data, and (4) draw conclusions.
In step 1, when researchers are formulating a problem to study, they often draw on theories and develop hypotheses. A theory is an interrelated, coherent set of ideas that helps to explain phenomena and facilitate predictions. It may suggest hypotheses, which are specific assertions and predictions that can be tested. For example, a theory on mentoring might state that sustained support and guidance from an adult makes a difference in the lives of children from impoverished backgrounds because the mentor gives the children opportunities to observe and imitate the behavior and strategies of the mentor.
This section outlines key aspects of five theoretical orientations to development: psychoanalytic, cognitive, behavioral and social cognitive, ethological, and ecological. Each contributes an important piece to the life-span development puzzle. Although the theories disagree about certain aspects of development, many of their ideas are complementary rather than contradictory. Together they let us see the total landscape of life-span development in all its richness.
PSYCHOANALYTIC THEORIES
Psychoanalytic theories describe development as primarily unconscious (beyond awareness) and heavily colored by emotion. Psychoanalytic theorists emphasize that behavior is merely a surface characteristic and that a true understanding of development requires analyzing the symbolic meanings of behavior and the deep inner workings of the mind. Psychoanalytic theorists also stress that early experiences with parents extensively shape development. These characteristics are highlighted in the main psychoanalytic theory, that of Sigmund Freud (1856–1939).
Freud’s Theory As Freud listened to, probed, and analyzed his patients, he became convinced that their problems were the result of experiences early in life. He thought that as children grow up, their focus of pleasure and sexual impulsesPage 21 shifts from the mouth to the anus and eventually to the genitals. As a result, we go through five stages of psychosexual development: oral, anal, phallic, latency, and genital (see Figure 10). Our adult personality, Freud (1917) claimed, is determined by the way we resolve conflicts between sources of pleasure at each stage and the demands of reality.
FIGURE 10 FREUDIAN STAGES. Because Freud emphasized sexual motivation, his stages of development are known as psychosexual stages. In his view, if the need for pleasure at any stage is either undergratified or overgratified, an individual may become fixated, or locked in, at that stage of development.
Freud’s theory has been significantly revised by a number of psychoanalytic theorists. Many of today’s psychoanalytic theorists maintain that Freud overemphasized sexual instincts; they argue that more emphasis should be placed on cultural experiences as determinants of an individual’s development. Unconscious thought remains a central theme, but conscious thought plays a greater role than Freud envisioned. One of the most influential revisionists of Freud’s ideas was Erik Erikson.
Sigmund Freud, the pioneering architect of psychoanalytic theory. How did Freud portray the organization of an individual’s personality?©Bettmann/Getty Images
Erikson’s Psychosocial Theory Erik Erikson (1902–1994) recognized Freud’s contributions but believed that Freud misjudged some important dimensions of human development. For one thing, Erikson (1950, 1968) said we develop in psychosocial stages, rather than in psychosexual stages as Freud maintained. According to Freud, the primary motivation for human behavior is sexual in nature; according to Erikson, it is social and reflects a desire to affiliate with other people. According to Freud, our basic personality is shaped during the first five years of life; according to Erikson, developmental change occurs throughout the life span. Thus, in terms of the early-versus-later-experience issue described earlier in the chapter, Freud viewed early experience as being far more important than later experiences, whereas Erikson emphasized the importance of both early and later experiences.
In Erikson’s theory, eight stages of development unfold as we go through life (see Figure 11). At each stage, a unique developmental task confronts individuals with a crisis that must be resolved. According to Erikson, this crisis is not a catastrophe but a turning point marked by both increased vulnerability and enhanced potential. The more successfully an individual resolves each crisis, the healthier development will be.
FIGURE 11 ERIKSON’S EIGHT LIFE-SPAN STAGES. Like Freud, Erikson proposed that individuals go through distinct, universal stages of development. Thus, in terms of the continuity-discontinuity issue discussed in this chapter, both favor the discontinuity side of the debate. Notice that the timing of Erikson’s first four stages is similar to that of Freud’s stages. What are the implications of saying that people go through stages of development?
Trust versus mistrust is Erikson’s first psychosocial stage, which is experienced in the first year of life. The development of trust during infancy sets the stage for a lifelong expectation that the world will be a good and pleasant place to live.
Autonomy versus shame and doubt is Erikson’s second stage. This stage occurs in late infancy and toddlerhood (1 to 3 years). After gaining trust in their caregivers, infants begin to discover that their behavior is their own. They start to assert their sense of independence or autonomy. They realize their will. If infants and toddlers are restrained too much or punished too harshly, they are likely to develop a sense of shame and doubt.
Erik Erikson with his wife, Joan, an artist. Erikson generated one of the most important developmental theories of the twentieth century. Which stage of Erikson’s theory are you in? Does Erikson’s description of this stage characterize you?©Jon Erikson/The Image Works
Initiative versus guilt, Erikson’s third stage of development, occurs during the preschool years. As preschool children encounter a widening social world, they face new challenges that require active, purposeful, responsible behavior. Feelings of guilt may arise, though, if the child is irresponsible and is made to feel too anxious.
Industry versus inferiority is Erikson’s fourth developmental stage, occurring approximately during the elementary school years. Children now need to direct their energy toward mastering knowledge and intellectual skills. The negative outcome is that the child may developPage 22 a sense of inferiority—feeling incompetent and unproductive.
During the adolescent years, individuals need to find out who they are, what they are all about, and where they are going in life. This is Erikson’s fifth developmental stage, identity versus identity confusion. If adolescents explore roles in a healthy manner and arrive at a positive path to follow in life, then they achieve a positive identity; if they do not, identity confusion reigns.
Intimacy versus isolation is Erikson’s sixth developmental stage, which individuals experience during early adulthood. At this time, individuals face the developmental task of forming intimate relationships. If young adults form healthy friendships and an intimate relationship with another, intimacy will be achieved; if not, isolation will result.
Generativity versus stagnation, Erikson’s seventh developmental stage, occurs during middle adulthood. By generativity Erikson means primarily a concern for helping the younger generation to develop and lead useful lives. The feeling of having done nothing to help the next generation is stagnation.
Integrity versus despair is Erikson’s eighth and final stage of development, which individuals experience in late adulthood. During this stage, a person reflects on the past. If the person’s life review reveals a life well spent, integrity will be achieved; if not, the retrospective glances likely will yield doubt or gloom—the despair Erikson described.
Jean Piaget, the famous Swiss developmental psychologist, changed the way we think about the development of children’s minds. What are some key ideas in Piaget’s theory?©Yves de Braine/Black Star/Stock Photo
Evaluating Psychoanalytic Theories Contributions of psychoanalytic theories include an emphasis on a developmental framework, family relationships, and unconscious aspects of the mind. Criticisms include a lack of scientific support, too much emphasis on sexual underpinnings, and an image of people that is too negative.
COGNITIVE THEORIES
Whereas psychoanalytic theories stress the importance of the unconscious, cognitive theories emphasize conscious thoughts. Three important cognitive theories are Jean Piaget’s cognitive developmental theory, Lev Vygotsky’s sociocultural cognitive theory, and the information-processing theory.
Piaget’s Cognitive Developmental Theory Piaget’s theory states that children go through four stages of cognitive development as they actively construct their understanding of the world. Two processes underlie this cognitive construction of the world: organization and adaptation. To make sense of our world, we organize our experiences. For example, we separate important ideas from less important ideas, and we connect one idea to another. In addition to organizing our observations and experiences, we adapt, adjusting to new environmental demands (Miller, 2015).
Piaget (1954) identified four stages in understanding the world (see Figure 12). Each stage is age-related and consists of a distinct way of thinking, a different way of understanding the world. Thus, according to Piaget (1896–1980), the child’s cognition is qualitatively different from one stage to another. What are Piaget’s four stages of cognitive development?
FIGURE 12 Piaget’s Four Stages of Cognitive Development. According to Piaget, how a child thinks—not how much the child knows—determines the child’s stage of cognitive development.(Photo credit left to right) ©Stockbyte/Getty Images; ©BananaStock/PunchStock; ©image100/Corbis; ©Purestock/Getty Images
- The sensorimotor stage, which lasts from birth to about 2 years of age, is the first Piagetian stage. In this stage, infants construct an understanding of the world by coordinating sensory experiences (such as seeing and hearing) with physical, motoric actions—hence the term sensorimotor.
- The preoperational stage, which lasts from approximatelyPage 23 2 to 7 years of age, is Piaget’s second stage. In this stage, children begin to go beyond simply connecting sensory information with physical action and represent the world with words, images, and drawings. However, according to Piaget, preschool children still lack the ability to perform what he calls operations, which are internalized mental actions that allow children to do mentally what they previously could only do physically. For example, if you imagine putting two sticks together to see whether they would be as long as another stick, without actually moving the sticks, you are performing a concrete operation.
- The concrete operational stage, which lasts from approximately 7 to 11 years of age, is the third Piagetian stage. In this stage, children can perform operations that involve objects, and they can reason logically when the reasoning can be applied to specific or concrete examples. For instance, concrete operational thinkers cannot imagine the steps necessary to complete an algebraic equation, a task that is too abstract for individuals at this stage of development.
- The formal operational stage, which appears between the ages of 11 and 15 and continues through adulthood, is Piaget’s fourth and final stage. In this stage, individuals move beyond concrete experiences and begin to think in abstract and more logical terms. As part of thinking more abstractly, adolescents develop images of ideal circumstances. They might think about what an ideal parent would be like and compare their parents to this ideal standard. They begin to entertain possibilities for the future and are fascinated with what they can be. In solving problems, they become more systematic, developing hypotheses about why something is happening the way it is and then testing these hypotheses. We will examine Piaget’s cognitive developmental theory further in other chapters.
Vygotsky’s Sociocultural Cognitive Theory Like Piaget, the Russian developmentalist Lev Vygotsky (1896–1934) argued that children actively construct their knowledge. However, Vygotsky (1962) gave social interaction and culture far more important roles in cognitive development than PiagetPage 24 did. Vygotsky’s theory is a sociocultural cognitive theory that emphasizes how culture and social interaction guide cognitive development.
Vygotsky portrayed the child’s development as inseparable from social and cultural activities (Daniels, 2017). He maintained that cognitive development involves learning to use the inventions of society, such as language, mathematical systems, and memory strategies. Thus in one culture, children might learn to count with the help of a computer; in another, they might learn by using beads. According to Vygotsky, children’s social interaction with more-skilled adults and peers is indispensable to their cognitive development. Through this interaction, they learn to use the tools that will help them adapt and be successful in their culture (Holzman, 2017). In later chapters, we will examine ideas about learning and teaching that are based on Vygotsky’s theory.
Lev Vygotsky was born the same year as Piaget, but he died much earlier, at the age of 37. There is considerable interest today in Vygotsky’s sociocultural cognitive theory of child development. What are some key characteristics of Vygotsky’s theory?©A.R. Lauria/Dr. Michael Cole, Laboratory of Human Cognition, University of California, San Diego
The Information-Processing Theory Information-processing theory emphasizes that individuals manipulate information, monitor it, and strategize about it. Unlike Piaget’s theory, but like Vygotsky’s theory, information-processing theory does not describe development as stage-like. Instead, according to this theory, individuals develop a gradually increasing capacity for processing information, which allows them to acquire increasingly complex knowledge and skills (Knapp & Morton, 2017).
Robert Siegler (2006, 2017), a leading expert on children’s information processing, states that thinking is information processing. In other words, when individuals perceive, encode, represent, store, and retrieve information, they are thinking. Siegler emphasizes that an important aspect of development is learning good strategies for processing information. For example, becoming a better reader might involve learning to monitor the key themes of the material being read.
Siegler (2006, 2017) also argues that the best way to understand how children learn is to observe them while they are learning. He emphasizes the importance of using the microgenetic method to obtain detailed information about processing mechanisms as they are occurring from moment to moment. Siegler concludes that most research methods indirectly assess cognitive change, being more like snapshots than movies. The microgenetic method seeks to discover not just what children know but the cognitive processes involved in how they acquired the knowledge. A typical microgenetic study will be conducted across a number of trials assessed at various times over weeks or months (Miller, 2015). A number of microgenetic studies have focused on a specific aspect of academic learning, such as how children learn whole number arithmetic, fractions, and other areas of math (Braithwaite & Siegler, 2018; Braithwaite, Tian, & Siegler, 2018). Microgenetic studies also have been used to discover how children learn a particular concept in science or a key component of learning to read.
The information-processing approach often uses the computer as an analogy to help explain the connection between cognition and the brain (Radvansky & Ashcraft, 2018). They describe the physical brain as the computer’s hardware, and cognition as its software. In this analogy, the sensory and perceptual systems provide an “input channel,” similar to the way data are entered into the computer. As input (information) comes into the mind, mental processes, or operations, act on it, just as the computer’s software acts on the data. The transformed input generates information that remains in memory much in the way a computer stores what it has worked on. Finally, the information is retrieved from memory and “printed out” or “displayed” (so to speak) as an observable response.
Computers provide a logical and concrete, but oversimplified, model of the mind’s processing of information. Inanimate computers and human brains function quite differently in some respects. For example, most computers receive information from a human who has already coded the information and removed much of its ambiguity. In contrast, each brain cell, or neuron, can respond to ambiguous information transmitted through sensory receptors such as the eyes and ears.
Computers can do some things better than humans. For instance, computers can perform complex numerical calculations much faster and more accurately than humans could ever hope to. Computers can also apply and follow rules more consistently and with fewer errors than humans and can represent complex mathematical patterns better than humans.
Still, the brain’s extraordinary capabilities will probably not be mimicked completely by computers at any time in the near future (Sternberg, 2017). For example, although a computer can improve its ability to recognize patterns or use rules of thumb to make decisions, it does not have the means to develop new learning goals. Furthermore, the human mind is aware of itself; the computer is not. Indeed, no computer isPage 25 likely to approach the richness of human consciousness.
Nonetheless, the computer’s role in cognitive and developmental psychology continues to increase. An entire scientific field called artificial intelligence (AI) focuses on creating machines capable of performing activities that require intelligence when they are done by people. And a new field titled developmental robotics is emerging that examines various developmental topics and issues using robots, such as motor development, perceptual development, information processing, and language development (Cangelosi & Schlesinger, 2015; Faghihi & Moustafa, 2017; Morse & Cangelosi, 2017). The hope is to build robots that are as much like humans as possible in order to gain a better understanding of human development (Vujovic & others, 2017).
Above is the humanoid robot iCub created by the Italian Institute of Technology to study aspects of children’s development such as perception, cognition, and motor development. In this situation, the robot, the size of a 3.5-year-old child, is catching a ball. This robot is being used by more than 20 laboratories worldwide and has 53 motors that move the head, arms and hands, waist, and legs. It also can see and hear, and has the sense of proprioception (body configuration) and movement (using gyroscopes).©Marco Destefanis/Pacific Press/Sipa/Newscom
Evaluating Cognitive Theories Contributions of cognitive theories include a positive view of development and an emphasis on the active construction of understanding. Criticisms include skepticism about the pureness of Piaget’s stages and too little attention to individual variations.
BEHAVIORAL AND SOCIAL COGNITIVE THEORIES
Behaviorism essentially holds that we can study scientifically only what can be directly observed and measured. Out of the behavioral tradition grew the belief that development is observable behavior that can be learned through experience with the environment (Maag, 2018). In terms of the continuity-discontinuity issue discussed earlier in this chapter, the behavioral and social cognitive theories emphasize continuity in development and argue that development does not occur in stage-like fashion. Let’s explore two versions of behaviorism: Skinner’s operant conditioning and Bandura’s social cognitive theory.
Skinner’s Operant Conditioning According to B. F. Skinner (1904–1990), through operant conditioning the consequences of a behavior produce changes in the probability of the behavior’s occurrence. A behavior followed by a rewarding stimulus is more likely to recur, whereas a behavior followed by a punishing stimulus is less likely to recur. For example, when an adult smiles at a child after the child has done something, the child is more likely to engage in that behavior again than if the adult gives the child a disapproving look.
In Skinner’s (1938) view, such rewards and punishments shape development. For Skinner the key aspect of development is behavior, not thoughts and feelings. He emphasized that development consists of the pattern of behavioral changes that are brought about by rewards and punishments. For example, Skinner would say that shy people learned to be shy as a result of experiences they had while growing up. It follows that modifications in an environment can help a shy person become more socially oriented.
- F. Skinner was a tinkerer who liked to make new gadgets. During her first two years of life the younger of his two daughters, Deborah, slept and played in Skinner’s enclosed Air-Crib, which he invented because he wanted to control her environment completely. The Air-Crib was sound-proofed and temperature controlled. Debbie, shown here as a child with her parents, is currently a successful artist, is married, and lives in London. What do you think about Skinner’s Air-Crib?©AP Images
Bandura’s Social Cognitive Theory Some psychologists agree with the behaviorists’ notion that development is learned and is influenced strongly by environmental interactions. However, unlike Skinner, they also see cognition as important in understanding development (Mischel, 2014). Social cognitive theory holds that behavior, environment, and cognition are the key factors in development.
American psychologist Albert Bandura (1925– ) is the leading architect of social cognitive theory. Bandura (1986, 2004, 2010a, b, 2012, 2015) emphasizes that cognitive processes have important links with the environment and behavior. His early research program focused heavily on observational learning (also called imitation or modeling), which is learning that occurs through observing what others do. For example, a young boy might observe his father yelling in anger and treating other people with hostility; with his peers, the young boy later acts very aggressively, showing the same characteristics asPage 26 his father’s behavior. Social cognitive theorists stress that people acquire a wide range of behaviors, thoughts, and feelings through observing others’ behavior and that these observations play a central role in life-span development.
Albert Bandura has been one of the leading architects of social cognitive theory. How does Bandura’s theory differ from Skinner’s?©Linda A Cicero/Stanford News Service
What is cognitive about observational learning in Bandura’s view? He proposes that people cognitively represent the behavior of others and then sometimes adopt this behavior themselves.
Bandura’s (2004, 2010a, b, 2012, 2015) most recent model of learning and development includes three elements: behavior, the person/cognition, and the environment. An individual’s confidence in being able to control his or her success is an example of a person factor; strategies are an example of a cognitive factor. As shown in Figure 13, behavior, person/cognitive, and environmental factors operate interactively.
FIGURE 13 BANDURA’S SOCIAL COGNITIVE MODEL. The arrows illustrate how relations between behavior, person/cognitive, and environment are reciprocal rather than one-way. Person/cognitive refers to cognitive processes (for example, thinking and planning) and personal characteristics (for example, believing that you can control your experiences).
Evaluating Behavioral and Social Cognitive Theories Contributions of the behavioral and social cognitive theories include an emphasis on scientific research and environmental determinants of behavior. Criticisms include too little emphasis on cognition in Skinner’s theory and inadequate attention paid to developmental changes.
developmental connection
Achievement
Bandura emphasizes that self-efficacy is a key person/cognitive factor in children’s achievement. Connect to “Socioemotional Development in Middle and Late Childhood.”
ETHOLOGICAL THEORY
Ethology stresses that behavior is strongly influenced by biology, is tied to evolution, and is characterized by critical or sensitive periods. These are specific time frames during which, according to ethologists, the presence or absence of certain experiences has a long-lasting influence on individuals (Bateson, 2015).
developmental connection
Attachment
Human babies go through a series of phases in developing an attachment to a caregiver. Connect to “Socioemotional Development in Infancy.”
European zoologist Konrad Lorenz (1903–1989) helped bring ethology to prominence. In his best-known research, Lorenz (1965) studied the behavior of greylag geese, which will follow their mothers as soon as they hatch. Lorenz separated the eggs laid by one goose into two groups. One group he returned to the goose to be hatched by her. The other group was hatched in an incubator. The goslings in the first group performed as predicted. They followed their mother as soon as they hatched. However, those in the second group, which saw Lorenz when they first hatched, followed him everywhere, as though he were their mother. Lorenz marked the goslings and then placed both groups under a box. Mother goose and “mother” Lorenz stood aside as the box was lifted. Each group of goslings went directly to its “mother.” Lorenz called this process imprinting—the rapid, innate learning that involves attachment to the first moving object seen.
Konrad Lorenz, a pioneering student of animal behavior, is followed through the water by three imprinted greylag geese. Describe Lorenz’s experiment with the geese. Do you think his experiment would have had the same results with human babies? Explain.©Nina Leen/Time Life Pictures/Getty Images
John Bowlby (1969, 1989) illustrated an important applicationPage 27 of ethological theory to human development. Bowlby stressed that attachment to a caregiver over the first year of life has important consequences throughout the life span. In his view, if this attachment is positive and secure, the individual will likely develop positively in childhood and adulthood. If the attachment is negative and insecure, life-span development will likely not be optimal. We will explore the concept of infant attachment in much greater detail later in this edition.
In Lorenz’s view, imprinting needs to take place at a certain, very early time in the life of the animal, or else it will not take place. This point in time is called a critical period. A related concept is that of a sensitive period, and an example of this is the time during infancy when, according to Bowlby, attachment should occur in order to promote optimal development of social relationships.
Another theory that emphasizes biological foundations of development—evolutionary psychology—will be presented in the chapter on “Biological Beginnings,” along with views on the role of heredity in development (Lickliter, 2018). In addition, we will examine a number of biological theories of aging in later chapters (Kauppila, Kauppila, & Larsson, 2017).
Contributions of ethological theory include a focus on the biological and evolutionary basis of development, and the use of careful observations in naturalistic settings. Criticisms include too much emphasis on biological foundations and a belief that the critical and sensitive period concepts might be too rigid.
ECOLOGICAL THEORY
While ethological theory stresses biological factors, ecological theory emphasizes environmental factors. One ecological theory that has important implications for understanding life-span development was created by Urie Bronfenbrenner (1917–2005). Bronfenbrenner’s ecological theory (Bronfenbrenner, 1986, 2004; Bronfenbrenner & Morris, 1998, 2006) holds that development reflects the influence of several environmental systems. The theory identifies five environmental systems: microsystem, mesosystem, exosystem, macrosystem, and chronosystem (see Figure 14).
FIGURE 14 Bronfenbrenner’s Ecological Theory of Development. Bronfenbrenner’s ecological theory consists of five environmental systems: microsystem, mesosystem, exosystem, macrosystem, and chronosystem.
The microsystem is the setting in which the individual lives. These contexts include the person’s family, peers, school, and neighborhood. It is in the microsystem that the most direct interactions with social agents take place—with parents, peers, and teachers, for example. The individual is not a passive recipient of experiences in these settings, but someone who helps to construct the settings.
The mesosystem involves relations between microsystems or connections between contexts. Examples are the relation of family experiences to school experiences, school experiences to religious experiences, and family experiences to peer experiences. For example, children whose parents have rejected them may have difficulty developing positive relationships with teachers.
developmental connection
Parenting
How are parent-child relationships and children’s peer relations linked? Connect to “Socioemotional Development in Early Childhood.”
The exosystem consists of links between a social setting in which the individual does not have an active role and the individual’s immediate context. For example, a husband’s or child’s experiences at home may be influenced by a mother’s experiences at work. The mother might receive a promotion that requires more travel, which might increase conflict with the husband and change patterns of interaction with the child.
The macrosystem involves the culture in which individuals live. Remember from earlier in the chapter that culture refers to the behavior patterns, beliefs, and all other products of a group of people that are passed on from generation to generation. Remember also that cross-cultural studies—the comparison of one culture with one or more other cultures—provide information about the generality of development.
The chronosystem consists of the patterning of environmental events and transitions over the life course, as well as sociohistorical circumstances. For example, divorce is one transition. Researchers have found that the negative effects of divorce on children often peak during the first year after the divorcePage 28 (Hetherington, 1993, 2006). By two years after the divorce, family interaction has become more stable. As an example of sociohistorical circumstances, consider how career opportunities for women have increased since the 1960s.
Bronfenbrenner (2004; Bronfenbrenner & Morris, 2006) subsequently added biological influences to his theory, describing it as a bioecological theory. Nonetheless, it is still dominated by ecological, environmental contexts.
Contributions of ecological theory include a systematic examination of macro and micro dimensions of environmental systems, and attention to connections between environmental systems. A further contribution of Bronfenbrenner’s theory is an emphasis on a range of social contexts beyond the family, such as neighborhood, religion, school, and workplace, as influential in children’s development (Shelton, 2018). Criticisms include inadequate attention to biological factors, as well as too little emphasis on cognitive factors.
Urie Bronfenbrenner developed ecological theory, a perspective that is receiving increased attention today. His theory emphasizes the importance of both micro and macro dimensions of the environment in which the child lives.Courtesy of Cornell University
AN ECLECTIC THEORETICAL ORIENTATION
No single theory described in this chapter can explain entirely the rich complexity of life-span development, but each has contributed to our understanding of development. Psychoanalytic theory best explains the unconscious mind. Erikson’s theory best describes the changes that occur during adult development. Piaget’s, Vygotsky’s, and the information-processing views provide the most complete description of cognitive development. The behavioral and social cognitive and ecological theories have been the most adept at examining the environmental determinants of development. The ethological theories have highlighted biology’s role and the importance of sensitive periods in development.
In short, although theories are helpful guides, relying on a single theory to explain development is probably a mistake. This book instead takes an eclectic theoretical orientation, which does not follow any one theoretical approach but rather selects from each theory whatever is considered its best features. In this way, you can view the study of development as it actually exists—with different theorists making different assumptions, stressing different empirical problems, and using different strategies to discover information. Figure 15 compares the main theoretical perspectives in terms of how they view important issues in life-span development.
FIGURE 15 A COMPARISON OF THEORIES AND ISSUES IN LIFE-SPAN DEVELOPMENTPage 29
Review Connect Reflect
LG3 Describe the main theories of human development.
Review
- What are the four steps of the scientific method? How can theory and hypotheses be defined? What are two main psychoanalytic theories? What are some contributions and criticisms of the psychoanalytic theories?
- What are three main cognitive theories? What are some contributions and criticisms of the cognitive theories?
- What are two main behavioral and social cognitive theories? What are some contributions and criticisms of the behavioral and social cognitive theories?
- What is the nature of ethological theory? What are some contributions and criticisms of the theory?
- What characterizes ecological theory? What are some contributions and criticisms of the theory?
- What is an eclectic theoretical orientation?
Connect
- The beginning of this section started with a question about whether special care might be able to repair the harm inflicted by child neglect. How might this question be answered differently using the various theories outlined?
Reflect Your Own Personal Journey of Life
- Which of the life-span theories do you think best explains your own development? Why?
4 Research on Life-Span Development
LG4 Explain how research on life-span development is conducted.
Methods for Collecting Data
Research Designs
Time Span of Research
Conducting Ethical Research
Minimizing Bias
If they follow an eclectic orientation, how do scholars and researchers determine that one feature of a theory is somehow better than another? Through scientific research, the features of theories can be tested and refined (Smetana, 2018; Smith & Davis, 2016).
Generally, research on life-span development is designed to test hypotheses, which in some cases are derived from the theories just described. Through research, theories are modified to reflect new data, and occasionally new theories arise. How are data about life-span development collected? What types of research designs are used to study life-span development? And what are some ethical considerations in conducting research on life-span development?
Science refines everyday thinking.
—Albert Einstein
German-born American Physicist, 20th Century
METHODS FOR COLLECTING DATA
Whether we are interested in studying attachment in infants, the cognitive skills of children, or social relationships in older adults, we can choose from several ways of collecting data (Salkind, 2017). Here we outline the measures most often used, beginning with observation.
Observation Scientific observation requires an important set of skills. For observations to be effective, they have to be systematic. We have to have some idea of what we are looking for. We have to know whom we are observing, when and where we will observe, how the observations will be made, and how they will be recorded.
Where should we make our observations? We have two choices: the laboratory and the everyday world.
When we observe scientifically, we often need to control certain factors that determine behavior but are not the focus of our inquiry (Leary, 2017). For this reason, some research on life-span development is conducted in a laboratory, a controlled setting where many of the complex factors of the “real world” are absent. For example, suppose you want to observe how children react when they see other people act aggressively. If you observe children in their homes or schools, you have no control over Page 30how much aggression the children observe, what kind of aggression they see, which people they see acting aggressively, or how other people treat the children. In contrast, if you observe the children in a laboratory, you can control these and other factors and therefore have more confidence about how to interpret your observations.
Laboratory research does have some drawbacks, however, including the following:
- It is almost impossible to conduct research without the participants knowing they are being studied.
- The laboratory setting is unnatural and therefore can cause the participants to behave unnaturally.
- People who are willing to come to a university laboratory may not accurately represent groups from diverse cultural backgrounds.
- People who are unfamiliar with university settings and with the idea of “helping science” may be intimidated by the laboratory setting.
Naturalistic observation provides insights that sometimes cannot be attained in the laboratory (Babbie, 2017). Naturalistic observation means observing behavior in real-world settings, making no effort to manipulate or control the situation. Life-span researchers conduct naturalistic observations at sporting events, child-care centers, work settings, malls, and other places people live in and frequent.
Naturalistic observation was used in one study that focused on conversations in a children’s science museum (Crowley & others, 2001). When visiting exhibits at the science museum, parents were far more likely to engage boys than girls in explanatory talk. This finding suggests a gender bias that encourages boys more than girls to be interested in science (see Figure 16).
FIGURE 16 Parents’ Explanations of Science to Sons and Daughters at a Science Museum. In a naturalistic observation study at a children’s science museum, parents were three times more likely to explain science to boys than to girls (Crowley & others, 2001). The gender difference occurred regardless of whether the father, the mother, or both parents were with the child, although the gender difference was greatest for fathers’ science explanations to sons and daughters.
Survey and Interview Sometimes the best and quickest way to get information about people is to ask them for it. One technique is to interview them directly. A related method is the survey (sometimes referred to as a questionnaire), which is especially useful when information from many people is needed. A standard set of questions is used to obtain peoples’ self-reported attitudes or beliefs about a particular topic. In a good survey, the questions are clear and unbiased, allowing respondents to answer unambiguously.
Surveys and interviews can be used to study topics ranging from religious beliefs to sexual habits to attitudes about gun control to beliefs about how to improve schools. Surveys and interviews may be conducted in person, over the telephone, and over the Internet.
One problem with surveys and interviews is the tendency of participants to answer questions in a way that they think is socially acceptable or desirable rather than to say what they truly think or feel (Madill, 2012). For example, on a survey or in an interview some individuals might say that they do not take drugs even though they do.
What are some important strategies in conducting observational research with children?©Philadelphia Inquirer/MCT/Landov Images
Standardized Test A standardized test has uniform procedures for administration and scoring. Many standardized tests allow a person’s performance to be compared with that of other individuals; thus they provide information about individual differences among people (Kaplan & Saccuzzo, 2018). One example is the Stanford-Binet intelligence test, which will be discussed in more detail later. Your score on the Stanford-Binet test tells you how your performance compares with that of thousands of other people who have taken the test.
One criticism of standardized tests is that they assume a person’s behavior is consistent and stable, yet personality and intelligence—two primary targets of standardized testing—can vary with the situation. For example, a person may perform poorly on a standardized intelligence test in an office setting but score much higher at home, where he or she is less anxious.
Case Study A case study is an in-depth look atPage 31 a single individual. Case studies are performed mainly by mental health professionals when, for either practical or ethical reasons, the unique aspects of an individual’s life cannot be duplicated and tested in other individuals. A case study provides information about one person’s experiences; it may focus on nearly any aspect of the subject’s life that helps the researcher understand the person’s mind, behavior, or other attributes (Yin, 2012). A researcher may gather information for a case study from interviews and medical records. In later chapters, we discuss vivid case studies, such as that of Michael Rehbein, who had much of the left side of his brain removed at 7 years of age to end severe epileptic seizures.
A case study can provide a dramatic, in-depth portrayal of an individual’s life, but we must be cautious when generalizing from this information. The subject of a case study is unique, with a genetic makeup and personal history that no one else shares. In addition, case studies involve judgments of unknown reliability. Researchers who conduct case studies rarely check to see if other professionals agree with their observations or findings.
Mahatma Gandhi was the spiritual leader of India in the middle of the twentieth century. Erik Erikson conducted an extensive case study of Gandhi’s life to determine what contributed to his identity development. What are some limitations of the case study approach?©Bettmann/Getty Images
Physiological Measures Researchers are increasingly using physiological measures when they study development at different points in the life span (Bell & others, 2018). Hormone levels are increasingly used in developmental research.
developmental connection
Cognitive Neuroscience and Aging
The cognitive neuroscience of aging involves the study of links between the brain’s development in older adults and changes in their cognitive skills. Connect to “Cognitive Development in Late Adulthood.”
Cortisol is a hormone produced by the adrenal gland that is linked to the body’s stress level and has been measured in studies of temperament, emotional reactivity, mood, and peer relations (Bangerter & others, 2017). Also, as puberty unfolds, the blood levels of certain hormones increase. To determine the nature of these hormonal changes, researchers analyze blood samples from adolescent volunteers (Ji & others, 2016).
Another physiological measure that is increasingly being used is neuroimaging, especially functional magnetic resonance imaging (fMRI), in which electromagnetic waves are used to construct images of a person’s brain tissue and biochemical activity (Park & Festini, 2018; Sullivan & Wilson, 2018). Figure 17 compares the brain images of two adolescents—one a non-drinker and the other a heavy drinker—while they are engaged in a memory task.
FIGURE 17 Brain Imaging of 15-Year-Old Adolescents. These two brain images indicate how alcohol can influence the functioning of an adolescent’s brain. Notice the pink and red coloring (which indicates effective brain functioning involving memory) in the brain of the 15-year-old non-drinker (left) while engaging in a memory task, and compare it with the lack of those colors in the brain of the 15-year-old heavy drinker (right) under the influence of alcohol.©Dr. Susan Tapert, University of California, San Diego
Electroencephalography (EEG) is a physiological measure that has been used for many decades to monitor overall electrical activity in the brain (Najjar & Brooker, 2017). Recent electroencephalograph researchPage 32 includes studies of infants’ attention and memory (Bell & others, 2018; Lusby & others, 2016). In many chapters of this edition, you will read about recent research on changes in the brain during prenatal development, infancy, childhood, adolescence, and aging.
developmental connection
Gene × Environment (G × E) Interaction
Increasingly, researchers are exploring how the interaction of a specific gene and a specific aspect of the environment affects development. Connect to “Biological Beginnings.”
Heart rate has been used as an indicator of infants’ and children’s development of perception, attention, and memory (Kim, Yang, & Lee, 2015). Further, heart rate has served as an index of different aspects of emotional development, such as inhibition, stress, and anxiety (Amole & others, 2017).
Researchers study eye movement to learn more about perceptual development and other developmental topics. Sophisticated eye-tracking equipment is especially being used to discover more detailed information about infants’ perception (Boardman & Fletcher-Watson, 2017), attention (Meng, Uto, & Hashiya, 2017), autism (Finke, Wilkinson, & Hickerson, 2017), and preterm birth effects on language development (Loi & others, 2017).
Yet another dramatic change in physiological methods is the advancement in methods to assess the actual units of hereditary information—genes—in studies of biological influences on development (Xing & others, 2018). For example, recent advances in gene assessment have revealed several specific genes that are linked to childhood obesity (Zandona & others, 2017). Also, in a later chapter you will read about the role of the ApoE4 gene in Alzheimer disease (Lancaster, Tabet, & Rusted, 2017; Parcon & others, 2018; Park & Festini, 2018).
RESEARCH DESIGNS
When you are conducting research on life-span development, in addition to selecting a method for collecting data, you also need to choose a research design (Jackson, 2017). There are three main types of research designs: descriptive, correlational, and experimental.
Descriptive Research All of the data-collection methods that we have discussed can be used in descriptive research, which aims to observe and record behavior. For example, a researcher might observe the extent to which people are altruistic or aggressive toward each other. By itself, descriptive research cannot prove what causes some phenomenon, but it can reveal important information about people’s behavior (Gravetter & Forzano, 2017).
Correlational Research In contrast with descriptive research, correlational research goes beyond describing phenomena to provide information that will help us to predict how people will behave (Gravetter & Forzano, 2017). In correlational research, the goal is to describe the strength of the relationship between two or more events or characteristics. The more strongly the two events are correlated (or related or associated), the more accurately we can predict one event from the other (Aron, Aron, & Coups, 2017).
For example, to find out whether children of permissive parents have less self-control than other children, you would need to carefully record observations of parents’ permissiveness and their children’s self-control. You might observe that the higher a parent was in permissiveness, the lower the child was in self-control. You would then analyze these data statistically to yield a numerical measure called a correlation coefficient, which is a number based on a statistical analysis that describes the degree of association between two variables. The correlation coefficient ranges from −1.00 to +1.00. A negative number means an inverse relation. In this example, you might find an inverse correlation between permissive parenting and children’s self-control with a coefficient of, say, −.30. By contrast, you might find a positive correlation of +.30 between parental monitoring of children and children’s self-control.
The higher the correlation coefficient (whether positive or negative), the stronger the association between the two variables. A correlation of 0 means that there is no association between the variables. A correlation of −.40 is stronger than a correlation of +.20 because we disregard whether the correlation is positive or negative in determining the strength of the correlation.
A caution is in order, however. Correlation does not equal causation (Howell, 2017). The correlational finding just mentioned does not mean that permissive parenting necessarily causes low self-control in children. It could have that meaning, but it also could indicate that a child’s lack of self-control caused the parents to throw up their arms in despair and give up trying to control the child. It also could mean that other factors, such as heredity or poverty, caused the correlation between permissive parenting and low self-control in children. Figure 18 illustrates these possible interpretations of correlational data.
FIGURE 18 POSSIBLE EXPLANATIONS OF CORRELATIONAL DATA©Jupiterimages/Getty Images
Experimental Research To study causality, researchersPage 33 turn to experimental research. An experiment is a carefully regulated procedure in which one or more factors believed to influence the behavior being studied are manipulated while all other factors are held constant. If the behavior under study changes when a factor is manipulated, we say that the manipulated factor has caused the behavior to change. In other words, the experiment has demonstrated cause and effect. The cause is the factor that was manipulated. The effect is the behavior that changed because of the manipulation. Nonexperimental research methods (descriptive and correlational research) cannot establish cause and effect because they do not involve manipulating factors in a controlled way.
Independent and Dependent Variables Experiments include two types of changeable factors, or variables: independent and dependent. An independent variable is a manipulated, influential, experimental factor. It is a potential cause. The label “independent” is used because this variable can be manipulated independently of other factors to determine its effect. An experiment may include one independent variable or several of them.
A dependent variable is a factor that can change in an experiment, in response to changes in the independent variable. As researchers manipulate the independent variable, they measure the dependent variable for any resulting effect.
For example, suppose that you conducted a study to determine whether women could change the breathing and sleeping patterns of their newborn babies by meditating during pregnancy. You might require one group of pregnant women to engage in a certain amount and type of meditation each day while another group would not meditate; the meditation is thus the independent variable. When the infants are born, you would observe and measure their breathing and sleeping patterns. These patterns are the dependent variable, the factor that changes as the result of your manipulation.
Experimental and Control Groups Experiments can involve one or more experimental groups and one or more control groups (Gravetter & Forzano, 2017). An experimental group is a group whose experience is manipulated. A control group is a comparison group that is as similar to the experimental group as possible and that is treated in every way like the experimental group except for the manipulated factor (independent variable). The control group serves as a baseline against which the effects of the manipulated condition can be compared.
Random assignment is an important principle for deciding whether each participant will be placed in the experimental group or in the control group. Random assignment means that researchers assign participants to experimental and control groups by chance. It reduces the likelihood that the experiment’s results will be due to any preexisting differences between groups. In the example involving the effects of meditation by pregnant women on the breathing and sleeping patterns of their newborns, you would randomly assign half of the pregnant women to engage in meditation over a period of weeks (the experimental group) and the other half to not meditate over the same number of weeks (the control group). Figure 19 illustrates the nature of experimental research.
FIGURE 19 Principles of Experimental Research. Imagine that you decide to conduct an experimental study of the effects of meditation by pregnant women on their newborns’ breathing and sleeping patterns. You would randomly assign pregnant women to experimental and control groups. The experimental-group women would engage in meditation over a specified number of sessions and weeks. The control group would not. Then, when the infants are born, you would assess their breathing and sleeping patterns. If the breathing and sleeping patterns of newborns whose mothers were in the experimental group are more positive than those of the control group, you would conclude that meditation caused the positive effects.Page 34
TIME SPAN OF RESEARCH
Researchers in life-span development have a special concern with studies that focus on the relation of age to some other variable. We have several options: Researchers can study different individuals of varying ages and compare them or they can study the same individuals as they age over time.
Cross-Sectional Approach The cross-sectional approach is a research strategy that simultaneously compares individuals of different ages. A typical cross-sectional study might include three groups of children: 5-year-olds, 8-year-olds, and 11-year-olds. Another study might include groups of 15-year-olds, 25-year-olds, and 45-year-olds. The groups can be compared with respect to a variety of dependent variables: IQ, memory, peer relations, attachment to parents, hormonal changes, and so on. All of this can be accomplished in a short time. In some studies, data are collected in a single day. Even in large-scale cross-sectional studies with hundreds of subjects, data collection does not usually take longer than several months to complete.
The main advantage of the cross-sectional study is that the researcher does not have to wait for the individuals to grow up or become older. Despite its efficiency, though, the cross-sectional approach has its drawbacks. It gives no information about how individuals change or about the stability of their characteristics. It can obscure the increases and decreases of development—the hills and valleys of growth and development. For example, a cross-sectional study of life satisfaction might reveal average increases and decreases, but it would not show how the life satisfaction of individual adults waxed and waned over the years. It also would not tell us whether the same adults who had positive or negative perceptions of life satisfaction in early adulthood maintained their relative degree of life satisfaction as they became middle-aged or older adults.
Longitudinal Approach The longitudinal approach is a research strategy in which the same individuals are studied over a period of time, usually several years or more. For example, in a longitudinal study of life satisfaction, the same adults might be assessed periodically over a 70-year time span—at the ages of 20, 35, 45, 65, and 90, for example.
Longitudinal studies provide a wealth of information about vital issues such as stability and change in development and the influence of early experience on later development, but they do have drawbacks (Almy & Cicchetti, 2018). They are expensive and time-consuming. The longer the study lasts, the more participants drop out—they move, get sick, lose interest, and so forth. The participants who remain may be dissimilar to those who drop out, biasing the outcome of the study. Those individuals who remain in a longitudinal study over a number of years may be more responsible and conformity-oriented, for example, or they might lead more stable lives.
Cohort Effects A cohort is a group of people who are born at a similar point in history and share similar experiences as a result, such as living through the Vietnam War or growing up in the same city around the same time. These shared experiences may produce a range of differences among cohorts (Ganguli, 2017; Messerlian & Basso, 2018; Schaie, 2016a, b). For example, people who were teenagers during the Great Depression are likely to differ from people who were teenagers during the booming 1990s in regard to their educational opportunities and economic status, how they were raised, and their attitudes toward sex and religion. In life-span development research, cohort effects are due to a person’s time of birth, era, or generation but not to actual age.
developmental connection
Intelligence
Cohort effects help to explain differences in the intelligence of people born at different points in time. Connect to “Physical and Cognitive Development in Middle Adulthood.”
Cohort effects are important because they can powerfully affect the dependent measures in a study ostensibly concerned with age (Grondahl & others, 2017; MacDonald & Stawski, 2016). Researchers have shown that it is especially important to be aware of cohort effects when assessing adult intelligence (Schaie, 2016a, b). Individuals born at different points in time—such as 1920, 1940, and 1960—have had varying opportunities for education. Individuals born in earlier years had less access to education, and this fact may have a significant effect on how this cohort performs on intelligence tests. Some researchers have found that cross-sectional studies indicate more than 90 percent of cognitive decline in aging is due to a slowing of processing speed, whereas longitudinal studies reveal that 20 percent or less of cognitive decline is due to processing speed (MacDonald & others, 2003; MacDonald & Stawski, 2015, 2016; Stawski, Sliwinski, & Hofer, 2013).
A recent example of a cohort effect occurred in a study in which older adults assessed in 2013–2014 engaged in a higher level of abstract reasoning than their counterparts assessed two decades earlier in 1990–1993 (Gerstorf & others, 2015). Another study illustrated how even a 10-year difference in when people are born can produce differences in cognitive and health outcomes (Christensen & others, 2013). In this study, Danish cohorts bornPage 35 in 1905 and 1915 were compared when each cohort reached their nineties, with the 1915 cohort showing significantly better cognitive and health profiles.
Cohort effects are due to a person’s time of birth or generation but not actually to age. Think for a moment about growing up in (left) the Great Depression and (right) today. How might your development differ depending on which of these time frames has dominated your life? your parents’ lives? your grandparents’ lives?(Left) Source: George Grantham Bain Collection, Library of Congress, Reproduction Number #LC-USZ62-63966; (right) ©Jamie Grill/Blend Images
Cross-sectional studies can show how different cohorts respond, but they can confuse age changes and cohort effects. Longitudinal studies are effective in studying age changes but only within one cohort.
Various generations have been given labels by the popular culture. Figure 20 describes the labels given to various generations, their historical periods, and the reasons for these labels. Consider the following description of the current generation of youth and think about how they differ from earlier youth generations:
FIGURE 20 Generations, Their Historical Periods, and Characteristics
They are history’s first “always connected” generation. Steeped in digital technology and social media, they treat their multi-tasking hand-held gadgets almost like a body part—for better or worse. More than 8 in 10 say they sleep with a cell phone glowing by the bed, poised to disgorge texts, phone calls, e-mails, songs, news, videos, games, and wake-up jingles. But sometimes convenience yields to temptation. Nearly two-thirds admit to texting while driving (Pew Research Center, 2010, p. 1).
How are today’s millennials experiencing youth differently from earlier generations?©Mark Bowden/Getty ImagesPage 36
CONDUCTING ETHICAL RESEARCH
Ethics in research may affect you personally if you ever serve as a participant in a study. In that event, you need to know your rights as a participant and the responsibilities of researchers to assure that these rights are safeguarded.
If you ever become a researcher in life-span development yourself, you will need an even deeper understanding of ethics. Even if you only carry out experimental projects in psychology courses, you must consider the rights of the participants in those projects (Salkind, 2017). A student might think, “I volunteer in a home for people with intellectual disabilities several hours per week. I can use the residents of the home in my study to see if a particular treatment helps improve their memory for everyday tasks.” But without proper permissions, the most well-meaning, kind, and considerate studies still violate the rights of the participants.
Today, proposed research at colleges and universities must pass the scrutiny of a research ethics committee before the research can be initiated (Kazdin, 2017; Leary, 2017). In addition, the American Psychological Association (APA) has developed ethics guidelines for its members. The code of ethics instructs psychologists to protect their participants from mental and physical harm. The participants’ best interests need to be kept foremost in the researcher’s mind. APA’s guidelines address four important issues:
- Informed consent. All participants must know what their research participation will involve and what risks might develop. Even after informed consent is given, participants must retain the right to withdraw from the study at any time and for any reason.
- Confidentiality. Researchers are responsible for keeping all of the data they gather on individuals completely confidential and, when possible, completely anonymous.
- Debriefing. After the study has been completed, participants should be informed of its purpose and the methods that were used. In most cases, the experimenter also can inform participants in a general manner beforehand about the purpose of the research without leading participants to behave in a way they think that the experimenter is expecting.
- Deception. In some circumstances, telling the participants beforehand what the research study is about substantially alters the participants’ behavior and invalidates the researcher’s data. In all cases of deception, however, the psychologist must ensure that the deception will not harm the participants and that the participants will be debriefed (told the complete nature of the study) as soon as possible after the study is completed.
MINIMIZING BIAS
Studies of life-span development are most useful when they are conducted without bias or prejudice toward any particular group of people. Of special concern is bias based on gender and bias based on culture or ethnicity.
Gender Bias For most of its existence, our society has had a strong gender bias, a preconceived notion about the abilities of women and men that prevented individuals from pursuing their own interests and achieving their potential (Brannon, 2017; Helgeson, 2017). Gender bias also has had a less obvious effect within the field of life-span development. For example, it is not unusual for conclusions to be drawn about females’ attitudes and behaviors from research conducted with males as the only participants.
Furthermore, when researchers find gender differences, their reports sometimes magnify those differences (Denmark & others, 1988). For example, a researcher might report that 74 percent of the men in a study had high achievement expectations versus only 67 percent of the women and go on to talk about the differences in some detail. In reality, this might be a rather small difference. It also might disappear if the study were repeated, or the study might have methodological problems that don’t allow such strong interpretations.
Pam Reid is a leading researcher who studies the effects of gender and ethnic bias on development. You can read about Dr. Reid’s interests in Connecting with Careers.
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connecting with careers
Pam Reid, Educational and Developmental Psychologist
When she was a child, Pam Reid liked to play with chemistry sets. Reid majored in chemistry during college and wanted to become a doctor. However, when some of her friends signed up for a psychology class as an elective, she decided to take the course. She was intrigued by learning about how people think, behave, and develop—so much so that she changed her major to psychology. Reid went on to obtain her Ph.D. in psychology (American Psychological Association, 2003, p. 16).
Pam Reid (center) with students at the University of Saint Joseph.Courtesy of Dr. Pam Reid
For a number of years, Reid was a professor of education and psychology at the University of Michigan, where she also was a research scientist at the Institute for Research on Women and Gender. Her main focus has been on how children and adolescents develop social skills, with a special interest in the development of African American girls (Reid & Zalk, 2001). She has been involved in numerous community activities, including the creation of a math and technology enrichment program for middle-school girls. In 2004, Reid became provost and executive vice-president at Roosevelt University in Chicago. From 2008 to 2015, she was president of the University of Saint Joseph in Hartford, Connecticut, before retiring to pursue other interests.
For more information about what educational psychologists do, see the Careers in Life-Span Development appendix.
Cultural and Ethnic Bias Today there is a growing realization that research on life-span development needs to include more people from diverse ethnic groups (Nieto & Bode, 2018). Historically, people from ethnic minority groups (African American, Latino, Asian American, and Native American) were excluded from most research in the United States and simply thought of as variations from the norm or average. If minority individuals were included in samples and their scores didn’t fit the norm, they were viewed as confounds or “noise” in data and discounted. Given the fact that individuals from diverse ethnic groups were excluded from research on life-span development for so long, we might reasonably conclude that people’s real lives are perhaps more varied than research data have indicated in the past.
Researchers also have tended to overgeneralize about ethnic groups (Schaefer, 2015). Ethnic gloss is using an ethnic label such as African American or Latino in a superficial way that portrays an ethnic group as being more homogeneous than it really is (Trimble, 1988). For example, a researcher might describe a research sample like this: “The participants were 60 Latinos.” A more complete description of the group might be something like this: “The 60 Latino participants were Mexican Americans from low-income neighborhoods in the southwestern area of Los Angeles. Thirty-six were from homes in which Spanish is the dominant language spoken, 24 from homes in which English is the main language spoken. Thirty were born in the United States, 30 in Mexico. Twenty-eight described themselves as Mexican American, 14 as Mexican, 9 as American, 6 as Chicano, and 3 as Latino.” Ethnic gloss can cause researchers to obtain samples of ethnic groups that are not representative of the group’s diversity, which can lead to overgeneralization and stereotyping.
Look at these two photographs, one of all non-Latino White males, the other of a diverse group of females and males from different ethnic groups, including some non-Latino White males. Consider a topic in life-span development, such as parenting, love, or cultural values. If you were conducting research on this topic, might the results of the study differ depending on whether the participants in your study were the individuals in the photograph on the left or on the right?(Left) ©Anthony Cassidy/The Image Bank/Getty Images; (right) ©Punchstock/Digital Vision
Ross Parke and Raymond Buriel (2006) described how research on ethnic minority children and their families has not been given adequate attention, especially in light of their significant rates of growth. Until recently, ethnic minority families were combined in the category “minority,” which masks important differences among ethnic groups as well as diversity within an ethnic group. When research has been conducted on ethnic groups, most often they are compared to non–Latino Whites to identify group differences. An assumption in two-group studies is that ethnic minority children have not advanced far enough to be the same as non–Latino White children and that this developmentalPage 38 lag contributes to ethnic minority children’s problems. Recently, some researchers have replaced two-group studies with more in-depth examination of variations within a single ethnic group. For example, a researcher might study how parents in an ethnic group adapt to the challenges they face as a minority in U.S. society and how these experiences contribute to the goals they have for their children. The continued growth of minority families in the United States in approaching decades will mainly be due to the immigration of Latino and Asian families (Bas-Sarmiento & others, 2017; Lo & others, 2017). Researchers need “to take into account their acculturation level and generational status of parents and children,” and consider how these factors might influence family processes and child outcomes (Parke & Buriel, 2006, p. 487). More attention also needs to be given to biculturalism because the complexity of diversity means that some children of color identify with two or more ethnic groups (Coard, 2017; Nieto & Bode, 2018). And language development research needs to focus more on second-language acquisition (usually English) and bilingualism and how they are linked to school achievement (Echevarria, Vogt, & Short, 2017).
Review Connect Reflect
LG4 Explain how research on life-span development is conducted.
Review
- What methods do researchers use to collect data on life-span development?
- What research designs are used to study human development?
- How is research conducted on the time span of people’s lives?
- What are researchers’ ethical responsibilities to the people they study?
- How can gender, cultural, and ethnic bias affect the outcome of a research study?
Connect
- Earlier in the chapter, you read about normative age-graded influences, normative history-graded influences, and nonnormative life events. Describe how these influences relate to what you just read about cohort effects.
Reflect Your Own Personal Journey of Life
- You and your parents grew up at different points in time. Consider some ways that you are different from your parents. Do you think some of your differences might be due to cohort effects? Explain.
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topical connections looking forward
In the chapter on “Biological Beginnings,” you will continue to learn about theory and research as you explore the biological underpinnings of life-span development. The influence of human evolution on development will be covered, including a discussion of natural selection and adaptive behavior. You will examine how the human genome works, the collaborative nature of genes, and how DNA plays a role in creating the person each of us becomes. You also will explore the challenges and choices people encounter when deciding to reproduce, including infertility treatments and adoption. And you will read in greater depth about the many sides of the age-old nature-nurture debate, focusing on the way heredity and environment interact.
reach your learning goals
Introduction
1 The Life-Span Perspective
LG1 Discuss the distinctive features of a life-span perspective on development.
The Importance of Studying Life-Span Development
Characteristics of the Life-Span Perspective
Some Contemporary Concerns
- Development is the pattern of change that begins at conception and continues through the human life span. It includes both growth and decline.
- Studying life-span development helps prepare us to take responsibility for children, gives us insight about our own lives, and gives us knowledge about what our lives will be like as we age.
- Life expectancy has increased dramatically in the last century, but life span has remained virtually the same.
- The life-span perspective includes these basic concepts: development is lifelong, multidimensional, multidirectional, and plastic; its study is multidisciplinary; it is contextual; it involves growth, maintenance, and regulation of loss; and it is a co-construction of biological, cultural, and individual factors.
- Three important sources of contextual influences are (1) normative age-graded influences, (2) normative history-graded influences, and (3) nonnormative life events.
- Health and well-being, parenting, education, sociocultural contexts and diversity, social policy, and technology are all areas of contemporary concern that are closely tied to life-span development.
- Important dimensions of the sociocultural context include culture, ethnicity, socioeconomic status, and gender.
- There is increasing interest in social policy issues related to children and to older adults.
- Recently, there also has been a dramatic infusion of technology in the lives of people of all ages, and the influence of technology on development is an important contemporary issue.
2 The Nature of Development
LG2 Identify the most important processes, periods, and issues in development.
Biological, Cognitive, and Socioemotional Processes
Periods of Development
The Significance of Age
Developmental Issues
- Three key categories of developmental processes are biological, cognitive, and socioemotional. Throughout development, there are extensive connections between these types of processes.
- The life span is commonly divided into the followingPage 40 development periods: prenatal, infancy, early childhood, middle and late childhood, adolescence, early adulthood, middle adulthood, and late adulthood.
- Recently, life-span developmentalists have described the human life span in terms of four ages, with a special focus on the third and fourth ages, as well as a distinction between the young-old and oldest-old.
- An important aspect of life-span development involves connections across periods of development.
- According to some experts on life-span development, too much emphasis is placed on chronological age.
- In studies covering adolescence through late adulthood, older people report the highest level of happiness.
- We often think of age only in terms of chronological age, but a full evaluation of age requires consideration of chronological, biological, psychological, and social age. Neugarten emphasizes that we are moving toward a society in which chronological age is only a weak predictor of development in adulthood.
- The nature-nurture issue focuses on the extent to which development is mainly influenced by nature (biological inheritance) or nurture (experience).
- The stability-change issue focuses on the degree to which we become older renditions of our early experience or develop into someone different from who we were earlier in development. A special aspect of the stability-change issue is the extent to which development is determined by early versus later experiences.
- Developmentalists describe development as continuous (gradual, or cumulative change) or as discontinuous (abrupt, or a sequence of stages). Most developmentalists recognize that extreme positions on the nature-nurture, stability-change, and continuity-discontinuity issues are unwise. Despite this consensus, there is still spirited debate on these issues.
3 Theories of Development
LG3 Describe the main theories of human development.
Psychoanalytic Theories
Cognitive Theories
Behavioral and Social Cognitive Theories Ethological Theory
Ecological Theory
An Eclectic Theoretical Orientation
- The scientific method involves four main steps: (1) conceptualize a problem, (2) collect data, (3) analyze data, and (4) draw conclusions.
- Theory is often involved in conceptualizing a problem. A theory is a coherent set of interrelated ideas that helps to explain phenomena and to facilitate predictions. Hypotheses are specific assertions and predictions, often derived from theory, that can be tested.
- According to psychoanalytic theories, development primarily depends on the unconscious mind and is heavily couched in emotion. Freud argued that individuals go through five psychosexual stages. Erikson’s theory emphasizes eight psychosocial stages of development: trust versus mistrust, autonomy versus shame and doubt, initiative versus guilt, industry versus inferiority, identity versus identity confusion, intimacy versus isolation, generativity versus stagnation, and integrity versus despair.
- Contributions of psychoanalytic theories include an emphasis on a developmental framework, family relationships, and unconscious aspects of the mind. Criticisms include a lack of scientific support, too much emphasis on sexual underpinnings, and an image of people that is too negative.
- Three main cognitive theories are Piaget’s, Vygotsky’s, and information-processing. Cognitive theories emphasize thinking, reasoning, language, and other cognitive processes. Piaget proposed a cognitive developmental theory in which children use their cognition to adapt to their world. In Piaget’s theory, children go through four cognitive stages: sensorimotor, preoperational, concrete operational, and formal operational. Vygotsky’s sociocultural cognitive theory emphasizes how culture and social interaction guide cognitive development. The information-processing approach emphasizes that individuals manipulate information, monitor it, and strategize about it.
- Contributions of cognitive theories includePage 41 an emphasis on the active construction of understanding and a positive view of development. Criticisms include giving too little attention to individual variations and skepticism about the pureness of Piaget’s stages.
- Two main behavioral and social cognitive theories are Skinner’s operant conditioning and Bandura’s social cognitive theory. In Skinner’s operant conditioning, the consequences of a behavior produce changes in the probability of the behavior’s occurrence. In Bandura’s social cognitive theory, observational learning is a key aspect of life-span development. Bandura emphasizes reciprocal interactions among person/cognition, behavior, and environment.
- Contributions of the behavioral and social cognitive theories include an emphasis on scientific research and a focus on environmental factors. Criticisms include inadequate attention to developmental changes and, in Skinner’s theory, too little attention to cognition.
- Ethology stresses that behavior is strongly influenced by biology, is tied to evolution, and is characterized by critical or sensitive periods. Contributions of ethological theory include a focus on the biological and evolutionary basis of development. Criticisms include rigidity of the concepts of critical and sensitive periods.
- Ecological theory emphasizes environmental contexts. Bronfenbrenner’s environmental systems view of development proposes five environmental systems: microsystem, mesosystem, exosystem, macrosystem, and chronosystem. Contributions of the theory include a systematic examination of macro and micro dimensions of environmental systems and attention to connections between them. Criticisms include inadequate attention to biological factors, as well as a lack of emphasis on cognitive factors.
- An eclectic theoretical orientation does not follow any one theoretical approach but rather selects from each theory whatever is considered the best in it.
4 Research on Life-Span Development
LG4 Explain how research on life-span development is conducted.
Methods for Collecting Data
Research Designs
Time Span of Research
Conducting Ethical Research
Minimizing Bias
- Methods for collecting data about life-span development include observation (in a laboratory or a naturalistic setting), survey (questionnaire) or interview, standardized test, case study, and physiological measures.
- Three main research designs are descriptive, correlational, and experimental. Descriptive research aims to observe and record behavior. In correlational research, the goal is to describe the strength of the relationship between two or more events or characteristics. Experimental research involves conducting an experiment, which can determine cause and effect. An independent variable is the manipulated, influential, experimental factor. A dependent variable is a factor that can change in an experiment, in response to changes in the independent variable. Experiments can involve one or more experimental groups and control groups. In random assignment, researchers assign participants to experimental and control groups by chance.
- When researchers decide about the time span of their research, they can conduct cross-sectional or longitudinal studies. Life-span researchers are especially concerned about cohort effects.
- Researchers’ ethical responsibilities include seeking participants’ informed consent, ensuring their confidentiality, debriefing them about the purpose and potential personal consequences of participating, and avoiding unnecessary deception of participants.
- Researchers need to guard against gender, cultural, and ethnic bias in research. Every effort should be made to make research equitable for both females and males. Individuals from varied ethnic backgrounds need to be included as participants in life-span research, and overgeneralization about diverse members within a group must be avoided.
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key terms
Bronfenbrenner’s ecological theory
continuity-discontinuity issue
eclectic theoretical orientation
normative age-graded influences
normative history-graded influences
key people
Paul Baltes
Albert Bandura
John Bowlby
Urie Bronfenbrenner
Raymond Buriel
Laura Carstensen
Marian Wright Edelman
Erik Erikson
Konrad Lorenz
Bernice Neugarten
Ross Parke
Jean Piaget
Robert Siegler
- F. Skinner
Lev Vygotsky
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appendix
Careers in Life-Span Development
The field of life-span development offers an amazing breadth of careers that can provide extremely satisfying work. College and university professors teach courses in many areas of life-span development. Teachers impart knowledge, understanding, and skills to children and adolescents. Counselors, clinical psychologists, nurses, and physicians help people of different ages to cope more effectively with their lives and improve their well-being.
These and many other careers related to life-span development offer many rewards. By working in the field of life-span development, you can help people to improve their lives, understand yourself and others better, possibly advance the state of knowledge in the field, and have an enjoyable time while you are doing these things. Many careers in life-span development pay reasonably well. For example, psychologists earn well above the median salary in the United States.
If you are considering a career in life-span development, would you prefer to work with infants? children? adolescents? older adults? As you go through this term, try to spend some time with people of different ages. Observe their behavior. Talk with them about their lives. Think about whether you would like to work with people of this age in your life’s work.
In addition, to find out about careers in life-span development you might talk with people who work in various jobs. For example, if you have some interest in becoming a school counselor, call a school, ask to speak with a counselor, and set up an appointment to discuss the counselor’s career and work. If you have an interest in becoming a nurse, call the nursing department at a hospital and set up an appointment to speak with the nursing coordinator about a nursing career.
Another way of exploring careers in life-span development is to work in a related job while you are in college. Many colleges and universities offer internships or other work experiences for students who major in specific fields. Course credit or pay is given for some of these jobs. Take advantage of these opportunities. They can help you decide whether this is the right career for you, and they can help you get into graduate school, if you decide you want to go.
An advanced degree is not absolutely necessary for some careers in life-span development, but usually you can considerably expand your opportunities (and income) by obtaining a graduate degree. If you think you might want to go to graduate school, talk with one or more professors about your interests, keep a high grade-point average, take appropriate courses, and realize that you likely will need to take the Graduate Record Examination at some point.
In the upcoming sections, we will profile a number of careers in four areas: education/research; clinical/counseling; medical/nursing/physical development; and families/relationships. These are not the only career options in life-span development, but the profiles should give you an idea of the range of opportunities available. For each career, we will describe the work and address the amount of education required and the nature of the training. We have provided chapter titles after some entries to help you find Connecting with Careers, the career profiles of people who hold some of these positions. The Web site for this book gives more detailed information about these careers in life-span development.
Education/Research
Numerous careers in life-span development involve education or research. The opportunities range from college professor to preschool teacher to school psychologist.
College/University Professor
Professors teach courses in life-span development at many types of institutions, including research universities with master’s or Ph.D. programs in life-span development, four-year colleges with no graduate programs, and community colleges. The courses in life-span development are offered in many different programs and schools, including psychology, education, nursing, child and family studies, social work, and medicine. In addition to teaching at the undergraduate or graduate level (or both), professors may conduct research, advise students or direct their research, and serve on college or university committees. Research is part of a professor’s job description at most universities with master’s and Ph.D. programs, but some college professors do not conduct research and focus instead on teaching.
Teaching life-span development at a college or university almost always requires a Ph.D. or master’s degree. Obtaining a Ph.D. usually takes four to six years of graduate work; a master’s degree requires approximately two years. The training involves taking graduate courses, learning to conduct research, and attending and presenting papers at professional meetings. Many graduate students work as teaching or research assistants for professors in an apprenticeship relationship that helps them to become competent teachers and researchers. Read the profiles of professors in the “Socioemotional Development in Middle Adulthood” and “Socioemotional Development in Late Adulthood” chapters.
Researcher
Some individuals in the field of life-span development work in research positions. They might work for a university, a government agency such as the National Institute of Mental Health, or private industry. They generate research ideas, plan studies, carry out the research, and usually attempt to publish the research in a scientific journal. A researcher often works in collaboration with other researchers. One researcher might spend much of his or her time in a laboratory; another researcher might work in the field, such as in schools, hospitals, and so on. Most researchers in life-span development have either a master’s or a Ph.D.
Elementary or Secondary School Teacher
Elementary and secondary school teachers teach one or more subject areas, preparing the curriculum, giving tests, assigning grades, monitoring students’ progress, conducting parent-teacher conferences, and attending workshops. Becoming an elementary or secondary school teacher requires a minimum of an undergraduate degree. The training involves taking a wide range of courses with a major or concentration in education as well as completing supervised practice teaching.
Exceptional Children (Special Education) Teacher
Teachers of exceptional children spend concentrated time with children who have a disability such as ADHD, intellectual disabilities, or cerebral palsy, or with children who are gifted. Usually some of their work occurs outside of the students’ regular classroom and some of it inside the students’ regular classroom. A teacher of exceptional children works closely with the student’s regular classroom teacher and parents to create the best educational program for the student. Teachers of exceptional children often continue their education after obtaining their undergraduate degree and attain a master’s degree.
Early Childhood Educator
Early childhood educators work on college faculties and usually teach in community colleges that award an associate degree in early childhood education. They have a minimum of a master’s degree in their field. In graduate school, they takePage 44 courses in early childhood education and receive supervisory training in child-care or early childhood programs.
Preschool/Kindergarten Teacher
Preschool teachers teach mainly 4-year-old children, and kindergarten teachers primarily teach 5-year-old children. They usually have an undergraduate degree in education, specializing in early childhood education. State certification to become a preschool or kindergarten teacher usually is required.
Family and Consumer Science Educator
Family and consumer science educators may specialize in early childhood education or instruct middle and high school students about such matters as nutrition, interpersonal relationships, human sexuality, parenting, and human development. Hundreds of colleges and universities throughout the United States offer two- and four-year degree programs in family and consumer science. These programs usually require an internship. Additional education courses may be needed to obtain a teaching certificate. Some family and consumer science educators go on to graduate school for further training, which provides a background for possible jobs in college teaching or research. Read a profile of a family and consumer science educator in the “Physical and Cognitive Development in Adolescence” chapter.
Educational Psychologist
Educational psychologists most often teach in a college or university and conduct research in various areas of educational psychology such as learning, motivation, classroom management, and assessment. They help train students for positions in educational psychology, school psychology, and teaching. Most educational psychologists have a doctorate in education, which requires four to six years of graduate work. Read a profile of an educational psychologist in the “Introduction” chapter.
School Psychologist
School psychologists focus on improving the psychological and intellectual well-being of elementary, middle/junior, and high school students. They give psychological tests, interview students and their parents, consult with teachers, and may provide counseling to students and their families. They may work in a centralized office in a school district or in one or more schools.
School psychologists usually have a master’s or doctoral degree in school psychology. In graduate school, they take courses in counseling, assessment, learning, and other areas of education and psychology.
Gerontologist
Gerontologists usually work in research in some branch of the federal or state government. They specialize in the study of aging with a particular focus on government programs for older adults, social policy, and delivery of services to older adults. In their research, gerontologists define problems to be studied, collect data, interpret the results, and make recommendations for social policy. Most gerontologists have a master’s or doctoral degree and have taken a concentration of coursework in adult development and aging.
Clinical/Counseling
A wide variety of clinical and counseling jobs are linked with life-span development. These range from child clinical psychologist to adolescent drug counselor to geriatric psychiatrist.
Clinical Psychologist
Clinical psychologists seek to help people with psychological problems. They work in a variety of settings, including colleges and universities, clinics, medical schools, and private practice. Some clinical psychologists only conduct psychotherapy; others do psychological assessment and psychotherapy; some also do research. Clinical psychologists may specialize in a particular age group, such as children (child clinical psychologist) or older adults (often referred to as a geropsychologist).
Clinical psychologists have either a Ph.D. (which involves clinical and research training) or a Psy.D. degree (which only involves clinical training). This graduate training usually takes five to seven years and includes courses in clinical psychology and a one-year supervised internship in an accredited setting toward the end of the training. Many geropsychologists pursue a year or two of postdoctoral training. Most states require clinical psychologists to pass a test in order to become licensed in the state and to call themselves clinical psychologists. Read a profile of a clinical psychologist in the “Prenatal Development and Birth” chapter.
Psychiatrist
Psychiatrists obtain a medical degree and then do a residency in psychiatry. Medical school takes approximately four years and the psychiatry residency another three to four years. Unlike most psychologists (who do not go to medical school), psychiatrists can administer drugs to clients. (Recently, several states gave clinical psychologists the right to prescribe drugs.)
Like clinical psychologists, psychiatrists might specialize in working with children (child psychiatry) or with older adults (geriatric psychiatry). Psychiatrists might work in medical schools in teaching and research roles, in a medical clinic or hospital, or in private practice. In addition to administering drugs to help improve the lives of people with psychological problems, psychiatrists also may conduct psychotherapy. Read a profile of a child psychiatrist in the “Socioemotional Development in Middle and Late Childhood” chapter.
Counseling Psychologist
Counseling psychologists work in the same settings as clinical psychologists and may do psychotherapy, teach, or conduct research. Many counseling psychologists do not do therapy with individuals who have severe mental disorders, such as schizophrenia.
Counseling psychologists go through much the same training as clinical psychologists, although in a graduate program in counseling rather than clinical psychology. Counseling psychologists have either a master’s degree or a doctoral degree. They also must go through a licensing procedure. One type of master’s degree in counseling leads to the designation of licensed professional counselor.
School Counselor
School counselors help students cope with adjustment problems, identify their abilities and interests, develop academic plans, and explore career options. The focus of the job depends on the age of the children. High school counselors advise students about vocational and technical training and admissions requirements for college, as well as about taking entrance exams, applying for financial aid, and choosing a major. Elementary school counselors mainly counsel students about social and personal problems. They may observe children in the classroom and at play as part of their work. School counselors may work with students individually, in small groups, or even in a classroom. They often consult with parents, teachers, and school administrators when trying to help students. School counselors usually have a master’s degree in counseling.
Career Counselor
Career counselors help individuals to identify their best career options and guide them in applying for jobs. They may work in private industry or at a college or university. They usually interview individuals and give them vocational and/or psychological tests to identify appropriate careers that fit their interests and abilities. Sometimes they help individuals to create résumés or conduct mock interviews to help them feel comfortable in a job interview. They might arrange and promote job fairs or other recruiting events to help individuals obtain jobs.
Rehabilitation Counselor
Rehabilitation counselors work with individuals to identify career options, develop adjustment and coping skills to maximize independence, and resolve problems created by a disability. A master’s degree in rehabilitation counseling or guidance or counseling psychology is generally considered the minimum educational requirement.
Social Worker
Many social workers are involved in helping people with social or economic problems. They may investigate, evaluate, and attemptPage 45 to rectify reported cases of abuse, neglect, endangerment, or domestic disputes. They may intervene in families and provide counseling and referral services to individuals and families. Some social workers specialize in a certain area. For example, a medical social worker might coordinate support services to people with a long-term disability; family-care social workers often work with families with children or an older adult who needs support services. Social workers often work for publicly funded agencies at the city, state, or national level, although increasingly they work in the private sector in areas such as drug rehabilitation and family counseling.
Social workers have a minimum of an undergraduate degree from a school of social work that includes coursework in sociology and psychology. Some social workers also have a master’s or doctoral degree. For example, medical social workers have a master’s degree in social work (M.S.W.) and complete graduate coursework and supervised clinical experiences in medical settings.
Drug Counselor
Drug counselors provide counseling to individuals with drug-abuse problems. Some drug counselors specialize in working with adolescents or older adults. They may work on an individual basis with a substance abuser or conduct group therapy. They may work in private practice, with a state or federal government agency, for a company, or in a hospital.
At a minimum, drug counselors complete an associate’s or certificate program. Many have an undergraduate degree in substance-abuse counseling, and some have master’s and doctoral degrees. Most states provide a certification procedure for obtaining a license to practice drug counseling.
Medical/Nursing/Physical Development
This third main area of careers in life-span development includes a wide range of choices in the medical and nursing areas, as well as jobs that focus on improving some aspect of a person’s physical development.
Obstetrician/Gynecologist
An obstetrician/gynecologist prescribes prenatal and postnatal care, performs deliveries in maternity cases, and treats diseases and injuries of the female reproductive system. Becoming an obstetrician/gynecologist requires a medical degree plus three to five years of residency in obstetrics/gynecology. Obstetricians may work in private practice, a medical clinic, a hospital, or a medical school.
Pediatrician
A pediatrician monitors infants’ and children’s health, works to prevent disease or injury, helps children attain optimal health, and treats children with health problems. Pediatricians have earned a medical degree and completed a three- to five-year residency in pediatrics.
Pediatricians may work in private practice or at a medical clinic, a hospital, or a medical school. Many pediatricians on the faculties of medical schools also teach and conduct research on children’s health and diseases. Read the profile of a pediatrician in the “Physical Development in Infancy” chapter.
Geriatric Physician
Geriatric physicians diagnose medical problems of older adults, evaluate treatment options, and make recommendations for nursing care or other arrangements. They have a medical degree and a three- to five-year residency in geriatric medicine. Like other doctors, geriatric physicians may work in private practice or at a medical clinic, a hospital, or a medical school. Those in medical school settings may not only treat older adults but also teach future physicians and conduct research.
Neonatal Nurse
Neonatal nurses deliver care to newborn infants. They may work with infants born under normal circumstances or premature and critically ill neonates. A minimum of an undergraduate degree in nursing with a specialization in the newborn is required. This training involves coursework in nursing and the biological sciences, as well as supervised clinical experiences.
Nurse-Midwife
A nurse-midwife formulates and provides comprehensive care to expectant mothers as they prepare to give birth, guides them through the birth process, and cares for them after the birth. The nurse-midwife also may provide care to the newborn, counsel parents on the infant’s development and parenting, and provide guidance about health practices. Becoming a nurse-midwife generally requires an undergraduate degree from a school of nursing. A nurse-midwife most often works in a hospital setting. Read the profile of a perinatal nurse in the “Prenatal Development and Birth” chapter.
Pediatric Nurse
Pediatric nurses monitor infants’ and children’s health, work to prevent disease or injury, and help children attain optimal health. They may work in hospitals, schools of nursing, or with pediatricians in private practice or at a medical clinic.
Pediatric nurses have a degree in nursing that takes two to five years to complete. They take courses in biological sciences, nursing care, and pediatrics, usually in a school of nursing. They also undergo supervised clinical experiences in medical settings. Some pediatric nurses go on to earn a master’s or doctoral degree in pediatric nursing.
Geriatric Nurse
Geriatric nurses seek to prevent or intervene in the chronic or acute health problems of older adults. They may work in hospitals, nursing homes, schools of nursing, or with geriatric medical specialists or psychiatrists in a medical clinic or in private practice. Like pediatric nurses, geriatric nurses take courses in a school of nursing and obtain a degree in nursing, which takes from two to five years. They complete courses in biological sciences, nursing care, and mental health as well as supervised clinical training in geriatric settings. They also may obtain a master’s or doctoral degree in their specialty. Read a profile of a geriatric nurse in the “Physical Development in Late Adulthood” chapter.
Physical Therapist
Physical therapists work with individuals who have a physical problem due to disease or injury to help them function as competently as possible. They may consult with other professionals and coordinate services for the individual. Many physical therapists work with people of all ages, although some specialize in working with a specific age group, such as children or older adults.
Physical therapists usually have an undergraduate degree in physical therapy and are licensed by a state. They take courses and undergo supervised training in physical therapy.
Occupational Therapist
Occupational therapists initiate the evaluation of clients with various impairments and manage their treatment. They help people regain, develop, and build skills that are important for independent functioning, health, well-being, security, and happiness. An “Occupational Therapist Registered” (OTR) must have a master’s and/or doctoral degree with education ranging from two to six years. Training includes occupational therapy courses in a specialized program. National certification is required, and licensing/registration is required in some states.
Therapeutic/Recreation Therapist
Therapeutic/recreation therapists maintain or improve the quality of life for people with special needs through intervention, leisure education, and recreation. They work in hospitals, rehabilitation centers, local government agencies, at-risk youth programs, and other settings. Becoming a therapeutic/recreation therapist requires an undergraduate degree with coursework in leisure studies and a concentration in therapeutic recreation. National certification is usually required. Coursework in anatomy, special education, and psychology is beneficial.
Audiologist
Audiologists assess and identify the presence and severity of hearing loss, as well as problems in balance. They may work in a medical clinic, with a physician in private practice, in a hospital, or in a medical school.
An audiologist completesPage 46 coursework and supervised training to earn a minimum of an undergraduate degree in hearing science. Some audiologists also obtain a master’s or doctoral degree.
Speech Therapist
Speech therapists identify, assess, and treat speech and language problems. They may work with physicians, psychologists, social workers, and other health care professionals in a team approach to help individuals with physical or psychological problems that involve speech and language. Some speech therapists specialize in working with individuals of a particular age or people with a particular type of speech disorder. Speech therapists have a minimum of an undergraduate degree in speech and hearing science or in a specific type of communication disorder. They may work in private practice, hospitals and medical schools, and government agencies.
Genetic Counselor
Genetic counselors identify and counsel families at risk for genetic disorders. They work as members of a health care team, providing information and support to families with members who have genetic defects or disorders or are at risk for a variety of inherited conditions. They also serve as educators and resource people for other health care professionals and the public. Nearly half of genetic counselors work in university medical centers; one-fourth work in private hospital settings.
Genetic counselors have specialized graduate degrees and experience in medical genetics and counseling. Most enter the field after majoring in undergraduate school in such disciplines as biology, genetics, psychology, nursing, public health, or social work. Read a profile of a genetic counselor in the “Biological Beginnings” chapter.
Families/Relationships
A number of careers and jobs related to life-span development focus on working with families and addressing relationship problems. These range from home health aide to marriage and family therapist.
Home Health Aide
A home health aide provides services to older adults in the older adults’ homes, helping them with basic self-care tasks. No higher education is required for this position. There is brief training by an agency.
Child Welfare Worker
Child protective services in each state employ child welfare workers. They protect children’s rights, evaluate any maltreatment, and may have children removed from their homes if necessary. A child social worker has a minimum of an undergraduate degree in social work.
Child Life Specialist
Child life specialists work with children and their families when the child needs to be hospitalized. They monitor the child’s activities, seek to reduce the child’s stress, and help the child to cope and to enjoy the hospital experience as much as possible. Child life specialists may provide parent education and develop individualized treatment plans based on an assessment of the child’s development, temperament, medical plan, and available social supports. Child life specialists have an undergraduate degree. They have taken courses in child development and education and usually completed additional courses in a child life program. Read a profile of a child life specialist in the “Physical and Cognitive Development in Middle and Late Childhood” chapter.
Marriage and Family Therapist
Marriage and family therapists work on the principle that many individuals who have psychological problems benefit when psychotherapy is provided in the context of a marital or family relationship. Marriage and family therapists may provide marital therapy, couple therapy to individuals in a relationship who are not married, and family therapy to two or more members of a family.
Marriage and family therapists have a master’s or a doctoral degree. They complete a training program in graduate school similar to a clinical psychologist’s but with the focus on marital and family relationships. In most states, it is necessary to go through a licensing procedure to practice marital and family therapy. Read the profile of a marriage and family therapist in the “Socioemotional Development in Early Childhood” chapter.
Further Careers
These are only a handful of careers that knowledge of developmental psychology can prepare you for. The Connecting with Careers profiles highlight additional careers, including an infant assessment specialist, child-care director, toy designer, health psychologist, college/career counselor, parent counselor, pastoral counselor, association director, and home hospice nurse. What other careers can you think of that require a knowledge of human development?
chapter 3
PRENATAL DEVELOPMENT AND BIRTH
chapter outline
Learning Goal 1 Describe prenatal development.
The Course of Prenatal Development
Teratology and Hazards to Prenatal Development
Learning Goal 2 Describe the birth process.
Preterm and Low Birth Weight Infants
Learning Goal 3 Explain the changes that take place in the postpartum period.
Emotional and Psychological Adjustments
©Steve Allen/The Image Bank/Getty Images
Diana and Roger married whenPage 75 he was 38 and she was 34. Both worked full-time and were excited when Diana became pregnant. Two months later, Diana began to have some unusual pains and bleeding. Just two months into her pregnancy she lost the baby. Although most early miscarriages are the result of embryonic defects, Diana thought deeply about why she had been unable to carry the baby to full term, and felt guilty that she might have done something “wrong.”
Six months later, Diana became pregnant again. Because she was still worried about her prior loss, she made sure to follow every government recommendation such as getting enough folic acid, avoiding certain types of dairy products that might harbor bacteria, and letting someone else change their cat’s litterbox to avoid toxoplasmosis. She and Roger read about pregnancy and signed up for birth preparation classes. Each Friday night for eight weeks they practiced techniques for dealing with contractions. They talked about what kind of parents they wanted to be and discussed what changes in their lives the baby would make. When they found out that their offspring was going to be a boy, they gave him a nickname: Mr. Littles.
Alex, also known as “Mr. Littles.”
Courtesy of Dr. John Santrock
This time, Diana’s pregnancy went well, and Alex, also known as Mr. Littles, was born. During the birth, however, Diana’s heart rate dropped precipitously, and she was given a stimulant to raise it. Apparently the stimulant also increased Alex’s heart rate and breathing to a dangerous point, and he had to be placed in a neonatal intensive care unit (NICU).
Several times a day, Diana and Roger visited Alex in the NICU. A number of babies in the NICU with very low birth weights had been in intensive care for weeks, and some of the babies were not doing well. Fortunately, Alex was in better health. After he had spent several days in the NICU, his parents were permitted to take home a very healthy Alex.
topical connections looking back
Genes form the biological basis of our development. They are passed on through mitosis, meiosis, and, ultimately, fertilization. The impact of our genes involves the genetic principles of dominant-recessive genes, sex-linked genes, genetic imprinting, and polygenically determined characteristics. Approximately 10 to 15 percent of U.S. couples have problems with fertility. Some of these problems can be solved through surgery, drugs, or in vitro fertilization. Whether a pregnancy occurs naturally or with assistance, the resulting infant’s development is shaped both by his or her genes (nature) and environment (nurture).
Page 76
preview
This chapter chronicles the truly remarkable developments from conception through birth. Imagine . . . at one time you were an organism floating in a sea of fluid in your mother’s womb. Let’s now explore what your development was like from the time you were conceived through the time you were born. We will explore normal development in the prenatal period, as well as the period’s hazards (such as high levels of mercury that were mentioned in the preceding story). We also will study the birth process and tests used to assess the newborn; discuss parents’ adjustment during the postpartum period; and evaluate parent-infant bonding.
1 Prenatal Development
LG1 Describe prenatal development.
The Course of Prenatal Development
Teratology and Hazards to Prenatal Development
Prenatal Care
Normal Prenatal Development
Imagine how Alex (“Mr. Littles”) came to be. Out of thousands of eggs and millions of sperm, one egg and one sperm united to produce him. Had the union of sperm and egg come a day or even an hour earlier or later, he might have been very different—maybe even of the opposite sex. Conception occurs when a single sperm cell from the male unites with an ovum (egg) in the female’s fallopian tube in a process called fertilization. Over the next few months, the genetic code discussed in the “Biological Beginnings” chapter directs a series of changes in the fertilized egg, but many events and hazards will influence how that egg develops and becomes tiny Alex.
The history of man for the nine months preceding his birth would, probably, be far more interesting, and contain events of greater moment, than all the three score and ten years that follow it.
—Samuel Taylor Coleridge
English Poet and Essayist, 19th Century
THE COURSE OF PRENATAL DEVELOPMENT
Typical prenatal development, which begins with fertilization and ends with birth, takes between 266 and 280 days (38 to 40 weeks). It can be divided into three periods: germinal, embryonic, and fetal.
The Germinal Period The germinal period is the period of prenatal development that takes place during the first two weeks after conception. It includes the creation of the fertilized egg, called a zygote; cell division; and the attachment of the zygote to the uterine wall.
Rapid cell division by the zygote continues throughout the germinal period (recall that this cell division occurs through a process called mitosis). Differentiation—specialization of cells to perform various tasks—starts to take place by approximately one week after conception. At this stage, the group of cells, now called the blastocyst, consists of an inner mass of cells that will eventually develop into the embryo, and the trophoblast, an outer layer of cells that later provides nutrition and support for the embryo. Implantation, the attachment of the zygote to the uterine wall, takes place about 11 to 15 days after conception. Figure 1 illustrates some of the most significant developments during the germinal period.
FIGURE 1 Significant Developments in the Germinal Period. Just one week after conception, cells of the blastocyst have already begun specializing. The germinal period ends when the blastocyst attaches to the uterine wall. Which of the steps shown in the drawing occur in the
laboratory when IVF is used?
The Embryonic Period The embryonic period is the period of prenatal development that occurs from two to eight weeks after conception. During the embryonic period, the rate of cell differentiation intensifies, support systems for cells form, and organs appear.
This period begins as the blastocyst attaches to the uterine wall. The mass of cells is now called an embryo, and three layers of cells form. The embryo’s endoderm is the inner layer of cells, which will develop into the digestive and respiratory systems. The mesoderm is the middle layer, which will become the circulatory system, bones, muscles, excretory system, and reproductive system. The ectoderm is the outermost layer, which will become the nervous system and brain, sensory receptors (ears, nose, and eyes, for example), and skin parts (hair and nails, for example). Every body part eventually develops from these three layers. The endoderm primarily produces internal body parts, the mesoderm primarily produces parts that surround the internal areas, and the ectoderm primarily produces surface parts.
As the embryo’s three layers form, life-support systems for the embryoPage 77 develop rapidly. These life-support systems include the amnion, the umbilical cord (both of which develop from the fertilized egg, not the mother’s body), and the placenta. The amnion is a sac (bag or envelope) that contains a clear fluid in which the developing embryo floats. The amniotic fluid provides an environment that is temperature and humidity controlled, as well as shockproof. The umbilical cord contains two arteries and one vein, and connects the baby to the placenta. The placenta consists of a disk-shaped group of tissues in which small blood vessels from the mother and the offspring intertwine but do not join.
Figure 2 illustrates the placenta, the umbilical cord, and the blood flow in the expectant mother and developing organism. Very small molecules—oxygen, water, salt, food from the mother’s blood, as well as carbon dioxide and digestive wastes from the offspring’s blood—pass back and forth between the mother and embryo or fetus (Cuffe & others, 2017; Dube, Desparois, & Lafond, 2018). Virtually any drug or chemical substance the pregnant woman ingests can cross the placenta to some degree, unless it is metabolized or altered during passage, or the molecules are too large to pass through the placental wall (Pfeifer & Bunders, 2016). Of special concern is the transfer through the placenta of drugs that can be harmful to the fetus, such as alcohol, nicotine, marijuana, and cocaine (Koren & Ornoy, 2018). For example, one study confirmed that ethanol crosses the human placenta and primarily reflects maternal alcohol use (Matlow & others, 2013). Another study revealed that cigarette smoke weakened and increased the oxidative stress of fetal membranes, from which the placenta develops (Menon & others, 2011). The stress hormone cortisol also can cross the placenta (Parrott & others, 2014). Large molecules that cannot pass through the placental wall include red blood cells and harmful substances, such as most bacteria, maternal wastes, and hormones. The complex mechanisms that govern the transfer of substances across the placental barrier are still not entirely understood (Huckle, 2017; Jeong & others, 2018; Vaughan & others, 2017; Zhang & others, 2018).
FIGURE 2 The Placenta and the Umbilical Cord. The area bound by the square is enlarged in the right half of the illustration. Arrows indicate the direction of blood flow. Maternal blood flows through the uterine arteries to the spaces housing the placenta, and it returns through the uterine veins to the maternal circulation. Fetal blood flows through the umbilical arteries into the capillaries of the placenta and returns through the umbilical vein to the fetal circulation. The exchange of materials takes place across the layer separating the maternal and fetal blood supplies, so the bloods never come into contact. What is known about how the placental barrier works and its importance?
By the time most women know they are pregnant, the major organs have begun to form. Organogenesis is the name given to the process of organ formation during the first two months of prenatal development. While they are being formed, the organs are especially vulnerable to environmental changes (Rios & Clevers, 2018; Schittny, 2017). In the third week after conception, the neural tube that eventually becomes the spinal cord forms. At about 21 days, eyes begin to appear, and at 24 days the cells for the heart begin to differentiate. During the fourth week, the urogenital system becomes apparent, and armPage 78 and leg buds emerge. Four chambers of the heart take shape, and blood vessels appear. From the fifth to the eighth week, arms and legs differentiate further; at this time, the face starts to form but still is not very recognizable. The intestinal tract develops and the facial structures fuse. At eight weeks, the developing organism weighs about 1/30 ounce and is just over 1 inch long.
The Fetal Period The fetal period, lasting about seven months, is the prenatal period between two months after conception and birth in typical pregnancies. Growth and development continue their dramatic course during this time.
Three months after conception (13 weeks), the fetus is about 3 inches long and weighs about four-fifths of an ounce. Its arms, legs, and head move randomly (or spontaneously), and its mouth opens and closes. The face, forehead, eyelids, nose, and chin are distinguishable, as are the upper arms, lower arms, hands, and lower limbs. In most cases, the genitals can be identified as male or female. By the end of the fourth month of pregnancy (17 weeks), the fetus has grown to about 5.5 inches in length and weighs about 5 ounces. At this time, a growth spurt occurs in the body’s lower parts. For the first time, the mother can feel the fetus move.
By the end of the fifth month (22 weeks), the fetus is about 12 inches long and weighs close to a pound. Structures of the skin have formed—toenails and fingernails, for example. The fetus is more active, showing a preference for a particular position in the womb. By the end of the sixth month (26 weeks), the fetus is about 14 inches long and has gained another half pound to a pound. The eyes and eyelids are completely formed, and a fine layer of hair covers the head. A grasping reflex is present and irregular breathing movements occur.
As early as six months of pregnancy (about 24 to 25 weeks after conception), the fetus for the first time has a chance of surviving outside the womb—that is, it is viable. Infants who are born early, or between 24 and 37 weeks of pregnancy, usually need help breathing because their lungs are not yet fully mature. By the end of the seventh month, the fetus is about 16 inches long and weighs about 3 pounds.
During the last two months of prenatal development, fatty tissues develop, and the functioning of various organ systems—heart and kidneys, for example—steps up. During the eighth and ninth months, the fetus grows longer and gains substantial weight—about another 4 pounds. At birth, the average American baby weighs 8 pounds and is about 20 inches long.
Figure 3 gives an overview of the main events during prenatalPage 79 development. Notice that instead of describing development in terms of germinal, embryonic, and fetal periods, Figure 3 divides prenatal development into equal periods of three months, called trimesters. Remember that the three trimesters are not the same as the three prenatal periods we have discussed. The germinal and embryonic periods occur in the first trimester. The fetal period begins toward the end of the first trimester and continues through the second and third trimesters. Viability (the chances of surviving outside the womb) begins at the end of the second trimester.
FIGURE 3 The Three Trimesters of Prenatal Development. Both the germinal and embryonic periods occur during the first trimester. The end of the first trimester as well as the second and third trimesters are part of the fetal period.
(Top) ©David Spears/PhotoTake, Inc.; (middle) ©Neil Bromhall/Science Source; (bottom) ©Brand X Pictures/PunchStock
developmental connection
Brain Development
At birth, infants’ brains weigh approximately 25 percent of what they will weigh in adulthood. Connect to “Physical Development in Infancy.”
Brain Development One of the most remarkable aspects of the prenatal period is the development of the brain (Andescavage & others, 2017). By the time babies are born, it has been estimated that they have as many as 20 to 100 billion neurons, or nerve cells, which handle information processing at the cellular level in the brain. During prenatal development, neurons spend time moving to the right locations and are starting to become connected. The basic architecture of the human brain is assembled during the first two trimesters of prenatal development. In typical development, the third trimester of prenatal developmentPage 80 and the first two years of postnatal life are characterized by gradual increases in connectivity and functioning of neurons.
Four important phases of the brain’s development during the prenatal period involve: (1) the neural tube, (2) neurogenesis, (3) neuronal migration, and (4) neural connectivity.
Neural Tube As the human embryo develops inside its mother’s womb, the nervous system begins forming as a long, hollow tube located on the embryo’s back. This pear-shaped neural tube, which forms at about 18 to 24 days after conception, develops out of the ectoderm. The tube closes at the top and bottom ends at about 27 days after conception (Keunen, Counsell, & Bender, 2017). Figure 4 shows that the nervous system still has a tubular appearance six weeks after conception.
FIGURE 4 Early Formation of the Nervous System. The photograph shows the primitive, tubular appearance of the nervous system at six weeks in the human embryo.
©Claude Edelmann/Science Source
Two birth defects related to a failure of the neural tube to close are anencephaly and spina bifida. The highest regions of the brain fail to develop when fetuses have anencephaly or when the head end of the neural tube fails to close, and these fetuses die in the womb, during childbirth, or shortly after birth (Steric & others, 2015). Spina bifida results in varying degrees of paralysis of the lower limbs (Li & others, 2018; Miller, 2017). Individuals with spina bifida usually need assistive devices such as crutches, braces, or wheelchairs (Grivell, Andersen, & Dodd, 2014). Both maternal diabetes and obesity place the fetus at risk for developing neural tube defects (Yu, Wu, & Yang, 2016). Also, one study found that maternal exposure to secondhand tobacco smoke was linked to neural tube defects (Suarez & others, 2011). Further, one study revealed that a high level of maternal stress during pregnancy was associated with neural tube defects in offspring (Li & others, 2013). A strategy that can help to prevent neural tube defects is for pregnant women to take adequate amounts of the B vitamin folic acid (Li & others, 2018; Viswanathan & others, 2017). A recent large-scale study in Brazil found that fortifying flour with folic acid significantly reduced the rate of neural tube defects (Santos & others, 2016).
Neurogenesis In a normal pregnancy, once the neural tube has closed, a massive proliferation of new immature neurons begins to takes place at about the fifth prenatal week and continues throughout the remainder of the prenatal period. The generation of new neurons is called neurogenesis, a process that continues through the remainder of the prenatal period but is largely complete by the end of the fifth month after conception (Keunen, Counsell, & Benders, 2017). At the peak of neurogenesis, it is estimated that as many as 200,000 neurons are generated every minute.
Neuronal Migration At approximately 6 to 24 weeks after conception, neuronal migration occurs. This involves cells moving outward from their point of origin to their appropriate locations and creating the different levels, structures, and regions of the brain (Keunen, Counsell, & Benders, 2017). Once a cell has migrated to its target destination, it must mature and develop a more complex structure.
Neural Connectivity At about the 23rd prenatal week, connections between neurons begin to occur, a process that continues postnatally (Miller, Huppi, & Mallard, 2016). We will have much more to say about the structure of neurons, their connectivity, and the development of the infant brain in the chapter on “Physical Development in Infancy.”
TERATOLOGY AND HAZARDS TO PRENATAL DEVELOPMENT
For Alex, the baby discussed at the opening of this chapter, the course of prenatal development went smoothly. His mother’s womb protected him as he developed. Despite this protection, the environment can affect the embryo or fetus in many well-documented ways.
Yelyi Nordone, 12, of New York City, casts her line out into the pond during Camp Spifida at Camp Victory, near Millville, Pennsylvania. Camp Spifida is a week-long residential camp for children with spina bifida.
©Bill Hughes/AP Images
General Principles A teratogen is any agent that can potentially cause a birth defect or negatively alter cognitive and behavioral outcomes. (The word comes from the Greek word tera, meaning “monster.”) So many teratogens exist that practically every fetus is exposed to at least some teratogens. For this reason, it is difficult to determine which teratogen causes which problem. In addition, it may take a long time for the effects of a teratogen to show up. Only about half of all potential effects appear at birth.
The field of study that investigates the causes of birth defects isPage 81 called teratology (Boschen & others, 2018; Cassina & others, 2017). Some exposures to teratogens do not cause physical birth defects but can alter the developing brain and influence cognitive and behavioral functioning. These deficits in functioning are explored by researchers in the field of behavioral teratology.
The dose, genetic susceptibility, and the time of exposure to a particular teratogen influence both the severity of the damage to an embryo or fetus and the type of defect:
- Dose. The dose effect is rather obvious—the greater the dose of an agent, such as a drug, the greater the effect.
- Genetic susceptibility. The type or severity of abnormalities caused by a teratogen is linked to the genotype of the pregnant woman and the genotype of the embryo or fetus (Lin & others, 2017). For example, how a mother metabolizes a particular drug can influence the degree to which the drug’s effects are transmitted to the embryo or fetus. The extent to which an embryo or fetus is vulnerable to a teratogen may also depend on its genotype (Middleton & others, 2017). Also, for unknown reasons, male fetuses are far more likely to be affected by teratogens than female fetuses.
- Time of exposure. Exposure to teratogens does more damage when it occurs at some points in development than at others (Feldkamp & others, 2017). Damage during the germinal period may even prevent implantation. In general, the embryonic period is more vulnerable than the fetal period.
Figure 5 summarizes additional information about the effects of time of exposure to a teratogen. The probability of a structural defect is greatest early in the embryonic period, when organs are being formed (Mazzu-Nascimento & others, 2017). Each body structure has its own critical period of formation. Recall from earlier discussions that a critical period is a fixed time period very early in development during which certain experiences or events can have a long-lasting effect on development. The critical periodPage 82 for the nervous system (week 3) is earlier than for arms and legs (weeks 4 and 5). Exposure to teratogens in the fetal period is more likely to cause problems in how organs function and may result in stunted growth rather than structural damage.
FIGURE 5 Teratogens and the Timing of Their Effects on Prenatal Development. The danger of structural defects caused by teratogens is greatest early in embryonic development. The period of organogenesis (red color) lasts for about six weeks. Later assaults by teratogens (blue-green color) mainly occur in the fetal period and instead of causing structural damage are more likely to stunt growth or cause problems involving organ function.
After organogenesis is complete, teratogens are less likely to cause anatomical defects. Instead, exposure during the fetal period is more likely to stunt growth or to create problems in the way organs function. This is especially true for the developing fetal brain, which continues to develop connections throughout pregnancy. To examine some key teratogens and their effects, let’s begin with drugs.
Prescription and Nonprescription Drugs Many U.S. women are given prescriptions for drugs while they are pregnant—especially antibiotics, analgesics, and asthma medications. Prescription as well as nonprescription drugs, however, may have effects on the embryo or fetus that the women never imagine.
Prescription drugs that can function as teratogens include antibiotics, such as streptomycin and tetracycline; some antidepressants; certain hormones, such as progestin and synthetic estrogen; and Accutane (the trade name for isotretinoin, a form of Vitamin A that is often used to treat acne) (Brown & others, 2018; Dathe & Schaefer, 2018). Among the birth defects caused by Accutane are heart defects, eye and ear abnormalities, and brain malformation. In a recent study, isotretinoin was the fourth most common drug given to female adolescents who were seeking contraception advice from a physician (Stancil & others, 2017). However, physicians did not give the adolescent girls adequate information about the negative effects of isotretinoin on offspring if the girls were to become pregnant. In a recent review of teratogens that should never be taken during the first trimester of pregnancy, isotretinoin was on the prohibited list (Eltonsy & others, 2016).
Nonprescription drugs that can be harmful include diet pills and high dosages of aspirin (Cadavid, 2017). Research indicates that low doses of aspirin pose no harm for the fetus but that high doses can contribute to maternal and fetal bleeding (Osikoya & others, 2017).
Psychoactive Drugs Psychoactive drugs act on the nervous system to alter states of consciousness, modify perceptions, and change moods. Examples include caffeine, alcohol, and nicotine, as well as illicit drugs such as cocaine, marijuana, and heroin.
Caffeine People often consume caffeine when they drink coffee, tea, or cola, or when they eat chocolate. Somewhat mixed results have been found for the extent to which maternal caffeine intake influences an offspring’s development (Adams, Keisberg, & Safranek, 2016; de Medeiros & others, 2017). However, a large-scale study of almost 60,000 women revealed that maternal caffeine intake was linked to lower birth weight and babies being born small for gestational age (Sengpiel & others, 2013). Also, the influence of maternal consumption of highly caffeinated energy drinks on the development of offspring has not yet been studied. The U.S. Food and Drug Administration recommends that pregnant women either not consume caffeine or consume it only sparingly.
Fetal alcohol spectrum disorders (FASD) are characterized by a number of physical abnormalities and learning problems. Notice the wide-set eyes, flat cheekbones, and thin upper lip in this child with FASD.
©Streissguth, A.P., Landesman-Dwyer S., Martin, J.C., & Smith, D.W. (1980). Teratogenic effects of alcohol in humans and laboratory animals. Science, 209, 353–361.
Alcohol Heavy drinking by pregnant women can be devastating to their offspring (Jacobson & others, 2017). Fetal alcohol spectrum disorders (FASD) are a cluster of abnormalities and problems that appear in the offspring of mothers who drink alcohol heavily during pregnancy (Del Campo & Jones, 2017; Helgesson & others, 2018). The abnormalities include facial deformities and defects of the limbs and heart (Pei & others, 2017; Petrenko & Alto, 2017). Most children with FASD have learning problems and many are below average in intelligence, with some having an intellectual disability (Khoury & Milligan, 2017). Also, in a recent study in the United Kingdom, the life expectancy of individuals with FASD was only 34 years of age, about 42 percent of the average life expectancy in the general population (Thanh & Jonsson, 2016). In this study, the most common causes of death among individuals with FASD were suicide (15 percent), accidents (14 percent), and poisoning by illegal drugs or alcohol (7 percent). A recent research review concluded that FASD is linked to a lower level of executive function in children, especially in planning (Kingdon, Cardoso, & McGrath, 2016). And in a recent study, FASD was associated with both externalized and internalized behavior problems in childhood (Tsang & others, 2016). Although many mothers of FASD infants are heavy drinkers, many mothers who are heavy drinkers do not have children with FASD or have one child with FASD and other children who do not have it.
What are some guidelines for alcohol use during pregnancy?Page 83 Even drinking just one or two servings of beer or wine or one serving of hard liquor a few days a week can have negative effects on the fetus, although it is generally agreed that this level of alcohol use will not cause fetal alcohol syndrome (Valenzuela & others, 2012; Sarman, 2018). The U.S. Surgeon General recommends that no alcohol be consumed during pregnancy, as does the French Alcohol Society (Rolland & others, 2016). Despite such recommendations, a recent large-scale U.S. study found that 11.5 percent of adolescent and 8.7 percent of adult pregnant women reported using alcohol in the previous month (Oh & others, 2017).
However, in Great Britain, the National Institutes of Care and Health Excellence have concluded that it is safe to consume one to two drinks not more than twice a week during pregnancy (O’Keeffe, Greene, & Kearney, 2014). Nonetheless, some research suggests that it may not be wise to consume alcohol at the time of conception.
Nicotine Cigarette smoking by pregnant women can also adversely influence prenatal development, birth, and postnatal development (Shisler & others, 2017). Preterm births and low birth weights, fetal and neonatal deaths, respiratory problems, and sudden infant death syndrome (SIDS, also known as crib death) are all more common among the offspring of mothers who smoked during pregnancy (Zhang & others, 2017). Prenatal smoking has been implicated in as many as 25 percent of infants being born with a low birth weight (Brown & Graves, 2013).
What are some links between expectant mothers’ nicotine intake and outcomes for their offspring?
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Maternal smoking during pregnancy also has been identified as a risk factor for the development of attention deficit hyperactivity disorder in offspring (Pohlabein & others, 2017; Weissenberger & others, 2017). A recent meta-analysis of 15 studies concluded that smoking during pregnancy increased the risk that children would have ADHD, and the risk of ADHD was greater for children whose mothers were heavy smokers (Huang & others, 2018). And in a recent study, maternal cigarette smoking during pregnancy was linked to higher rates of cigarette smoking among offspring at 16 years of age (De Genna & others, 2016). Further, a recent study revealed that daughters whose mothers smoked during their pregnancy were more likely to subsequently smoke during their own pregnancy (Ncube & Mueller, 2017). Studies also indicate that environmental tobacco smoke is linked to impaired connectivity of the thalamus and prefrontal cortex in newborns (Salzwedel & others, 2016). Another study found that maternal exposure to environmental tobacco smoke during prenatal development increased the risk of stillbirth (Varner & others, 2014). Also, one study found that maternal smoking during pregnancy was associated with increased risk of asthma and wheezing in adolescence (Hollams & others, 2014).
Despite the plethora of negative outcomes for maternal smoking during pregnancy, a recent large-scale U.S. study revealed that 23 percent of adolescent and 15 percent of adult pregnant women reported using tobacco in the previous month (Oh & others, 2017). And a final point about nicotine use during pregnancy involves the recent dramatic increase in the use of e-cigarettes (Wagner, Camerota, & Propper, 2017; Tegin & others, 2018). A recent study found that misconceptions about e-cigarettes were common among pregnant women (Mark & others, 2015). Women who were using e-cigarettes during pregnancy often stated that e-cigarettes were less harmful than regular cigarettes (74 percent) and helpful in easing smoking cessation (72 percent).
Cocaine Does cocaine use during pregnancy harm the developing embryo and fetus? A research review concluded that cocaine quickly crosses the placenta to reach the fetus (De Giovanni & Marchetti, 2012). The most consistent finding is that cocaine exposure during prenatal development is associated with reduced birth weight, length, and head circumference (Gouin & others, 2011). Also, in other studies, prenatal cocaine exposure has been linked to impaired connectivity of the thalamus and prefrontal cortex in newborns (Salzwedel & others, 2016); impaired motor development at 2 years of age and a slower rate of growth through 10 years of age (Richardson, Goldschmidt, & Willford, 2008); self-regulation problems at age 12 (Minnes & others, 2016); elevated blood pressure at 9 years of age (Shankaran & others, 2010); impaired language development and information processing (Beeghly & others, 2006), including attention deficits (especially impulsivity) (Accornero & others, 2006; Richardson & others, 2011); learning disabilities at age 7 (Morrow & others, 2006); increased likelihood of being in a special education program that involves supportive services (Levine & others, 2008); and increased behavioral problems, especially externalizing problems such as high rates of aggression and delinquency (Minnes & others, 2010; Richardson & others, 2011).
This baby was exposed to cocaine prenatally. What are some of the possible developmental effects of prenatal exposure to cocaine?
©Chuck Nacke/Alamy
Some researchers argue that these findings should be interpreted cautiously (Accornero & others, 2006). Why? Because other factors in the lives of pregnant women who use cocaine (such as poverty, malnutrition, and other substance abuse) often cannot be ruled out as possible contributors to the problems found in theirPage 84 children (Hurt & others, 2005; Messiah & others, 2011). For example, cocaine users are more likely than nonusers to smoke cigarettes, use marijuana, drink alcohol, and take amphetamines.
Despite these cautions, the weight of research evidence indicates that children born to mothers who use cocaine are likely to have neurological, medical, and cognitive deficits (Cain, Bornick, & Whiteman, 2013; Field, 2007; Martin & others, 2016; Mayer & Zhang, 2009; Parcianello & others, 2018; Richardson & others, 2011; Scott-Goodwin, Puerto, & Moreno, 2016). Cocaine use by pregnant women is never recommended.
Marijuana An increasing number of studies find that marijuana use by pregnant women also has negative outcomes for offspring (Ruisch & others, 2018; Volkow, Compton, & Wargo, 2017). For example, researchers found that prenatal marijuana exposure was related to lower intelligence in children (Goldschmidt & others, 2008). Research reviews concluded that marijuana use during pregnancy alters brain functioning in the fetus (Calvigioni & others, 2014; Jaques & others, 2014). In a recent meta-analysis, marijuana use during pregnancy was linked to offsprings’ low birth weight and greater likelihood of being placed in a neonatal intensive care unit (Gunn & others, 2016). One study also indicated that prenatal exposure to marijuana was linked to marijuana use at 14 years of age (Day, Goldschmidt, & Thomas, 2006). Another study discovered that marijuana use by pregnant women was associated with stillbirth (Varner & others, 2014). In sum, marijuana use is not recommended for pregnant women.
Despite increasing evidence of negative outcomes, a recent survey found that marijuana use by pregnant women increased from 2.4 percent in 2002 to 3.85 percent in 2014 (Brown & others, 2016). And there is considerable concern that marijuana use by pregnant women may increase further given the growing number of states that have legalized marijuana (Chasnoff, 2017; Hennessy, 2018).
Heroin It is well documented that infants whose mothers are addicted to heroin show several behavioral difficulties at birth (Angelotta & Appelbaum, 2017). The difficulties include withdrawal symptoms, such as tremors, irritability, abnormal crying, disturbed sleep, and impaired motor control. Many still show behavioral problems at their first birthday, and attention deficits may appear later in development. The most common treatment for heroin addiction, methadone, is associated with very severe withdrawal symptoms in newborns (Lai & others, 2017).
Incompatible Blood Types Incompatibility between the mother’s and father’s blood types poses another risk to prenatal development (Yogev-Lifshitz & others, 2016). Blood types are created by differences in the surface structure of red blood cells. One type of difference in the surface of red blood cells creates the familiar blood groups—A, B, O, and AB. A second difference creates what is called Rh-positive and Rh-negative blood. If a surface marker, called the Rh-factor, is present in an individual’s red blood cells, the person is said to be Rh-positive; if the Rh-marker is not present, the person is said to be Rh-negative. If a pregnant woman is Rh-negative and her partner is Rh-positive, the fetus may be Rh-positive. If the fetus’ blood is Rh-positive and the mother’s is Rh-negative, the mother’s immune system may produce antibodies that will attack the fetus. This can result in any number of problems, including miscarriage or stillbirth, anemia, jaundice, heart defects, brain damage, or death soon after birth (Fasano, 2017).
An explosion at the Chernobyl nuclear power plant in the Ukraine produced radioactive contamination that spread to surrounding areas. Thousands of infants were born with health problems and deformities as a result of the nuclear contamination, including this boy whose arm did not form. In addition to radioactive contamination, what are some other types of environmental hazards to prenatal development?
©Sergey Guneev/RIA Novosti
Generally, the first Rh-positive baby of an Rh-negative mother is not at risk, but with each subsequent pregnancy the risk increases. A vaccine (RhoGAM) may be given to the mother within three days of the first child’s birth to prevent her body from making antibodies that will attack any future Rh-positive fetuses in subsequent pregnancies (Aitken & Tichy, 2015). Also, babies affected by Rh incompatibility can be given blood transfusions before or right after birth (Fasano, 2017).
Environmental Hazards Many aspects of our modern industrial world can endanger the embryo or fetus. Some specific hazards to the embryo or fetus include radiation, toxic wastes, and other chemical pollutants (Jeong & others, 2018; Sreetharan & others, 2017).
X-ray radiation can affect the developing embryo or fetus, especially in the first several weeks after conception, when women do not yet know they are pregnant. Women and their physicians should weigh the risk of an X-ray when an actual or potential pregnancy is involved (Rajaraman & others, 2011). However, a routine diagnostic X-ray of a body area other than the abdomen, with the woman’s abdomen protected by a lead apron,Page 85 is generally considered safe (Brent, 2009, 2011).
Environmental pollutants and toxic wastes are also sources of danger to unborn children. Among the dangerous pollutants are carbon monoxide, mercury, and lead, as well as certain fertilizers and pesticides (Wang & others, 2017).
Maternal Diseases Maternal diseases and infections can produce defects in offspring by crossing the placental barrier, or they can cause damage during birth (Cuffe & others, 2017; Koren & Ornoy, 2018). Rubella (German measles) is one disease that can cause prenatal defects. A recent study found that cardiac defects, pulmonary problems, and microcephaly (a condition in which the baby’s head is significantly smaller and less developed than normal) were among the most common fetal and neonatal outcomes when pregnant women have rubella (Yazigi & others, 2017). Women who plan to have children should have a blood test before they become pregnant to determine whether they are immune to the disease.
Syphilis (a sexually transmitted infection) is more damaging later in prenatal development—four months or more after conception. Damage to offspring includes stillbirth, eye lesions (which can cause blindness), skin lesions, and congenital syphilis (Braccio, Sharland, & Ladhani, 2016). Penicillin is the only known treatment for syphilis during pregnancy (Moline & Smith, 2016).
Another infection that has received widespread attention is genital herpes. Newborns contract this virus when they are delivered through the birth canal of a mother with genital herpes (Sampath, Maduro, & Schillinger, 2017). About one-third of babies delivered through an infected birth canal die; another one-fourth become brain damaged. If an active case of genital herpes is detected in a pregnant woman close to her delivery date, a cesarean section can be performed (in which the infant is delivered through an incision in the mother’s abdomen) to keep the virus from infecting the newborn (Pinninti & Kimberlin, 2013).
AIDS is a sexually transmitted infection that is caused by the human immunodeficiency virus (HIV), which destroys the body’s immune system (Taylor & others, 2017). A mother can infect her offspring with HIV/AIDS in three ways: (1) during gestation across the placenta, (2) during delivery through contact with maternal blood or fluids, and (3) postpartum (after birth) through breast feeding. The transmission of AIDS through breast feeding is especially problematic in many developing countries (UNICEF, 2013). Babies born to HIV-infected mothers can be (1) infected and symptomatic (show HIV symptoms), (2) infected but asymptomatic (not show HIV symptoms), or (3) not infected at all. An infant who is infected and asymptomatic may still develop HIV symptoms through 15 months of age.
developmental connection
Conditions, Diseases, and Disorders
The greatest incidence of HIV/AIDS is in sub-Saharan Africa, where as many as 30 percent of mothers have HIV; many are unaware that they are infected with the virus. Connect to “Physical Development in Infancy.”
The more widespread disease of diabetes, characterized by high levels of sugar in the blood, also affects offspring (Briana & others, 2018; Haertle & others, 2017; Kaseva & others, 2018). A research review indicated that newborns with physical defects are more likely to have diabetic mothers (Eriksson, 2009). Women who have gestational diabetes also may deliver very large infants (weighing 10 pounds or more), and the infants are at risk for diabetes (Alberico & others, 2014) and cardiovascular disease (Amrithraj & others, 2017). One study found that 5- to 16-year-old Mexican American children were more likely to be obese if their mothers had gestational diabetes (women who have never had diabetes before but have high blood sugar levels during pregnancy) (Page & others, 2014). Also, a recent research review concluded that pregestational diabetes increases the risk of fetal heart disease (Pauliks, 2015).
Other Parental Factors So far we have discussed a number of drugs, environmental hazards, maternal diseases, and incompatible blood types that can harm the embryo or fetus. Here we will explore other characteristics of the mother and father that can affect prenatal and child development, including nutrition, age, and emotional states and stress.
Because the fetus depends entirely on its mother for nutrition, it is important for pregnant women to have good nutritional habits. In Kenya, this government clinic provides pregnant women with information about how their diet can influence the health of their fetus and offspring. What might the information about diet be like?
©Delphine Bousquet/AFP/Getty Images
Maternal Diet and Nutrition A developing embryo or fetus depends completely on its mother for nutrition, which comes from the mother’s blood (Kominiarek & Peaceman, 2017). The nutritional status of the embryo or fetus is determined byPage 86 the mother’s total caloric intake as well as her intake of proteins, vitamins, and minerals. Children born to malnourished mothers are more likely than other children to be malformed.
developmental connection
Conditions, Diseases, and Disorders
What are some key factors that influence whether individuals will become obese? Connect to “Physical and Cognitive Development in Early Adulthood.”
Maternal obesity adversely affects pregnancy outcomes through increased rates of hypertension, diabetes, respiratory complications, infections, and depression in the mother (Kumpulainen & others, 2018; Preston, Reynolds, & Pearson, 2018). A recent study revealed that at 14 weeks following conception fetuses of obese pregnant women had less efficient cardiovascular functioning (Ingul & others, 2016). An earlier study found that maternal overweight and obesity during pregnancy were associated with an increased risk of preterm birth, especially extremely preterm delivery (Cnattingius & others, 2013). Further, research indicates that maternal obesity during pregnancy is linked to cardiovascular disease and type 2 diabetes in the adolescent and adult offspring of these mothers (Agarwal & others, 2018; Slack & others, 2018). Research studies have found that maternal obesity is linked to an increase in stillbirth (Gardosi & others, 2013) and increased likelihood that the newborn will be placed in a neonatal intensive care unit (Minsart & others, 2013). Further, two recent research reviews concluded that maternal obesity during pregnancy is associated with an increased likelihood of offspring being obese in childhood and adulthood (Pinto Pereira & others, 2016; Santangeli, Sattar, & Huda, 2015). Management of obesity that includes weight loss and increased exercise prior to pregnancy is likely to benefit the mother and the baby (Dutton & others, 2018; Hanson & others, 2017). Limiting gestational weight gain to 11 to 20 pounds among pregnant women is likely to improve outcomes for the mother and the child (Simmons, 2011).
One aspect of maternal nutrition that is important for normal prenatal development is folic acid, a B-complex vitamin (Li & others, 2018; Viswanathan & others, 2017). A study of more than 34,000 women showed that taking folic acid either alone or as part of a multivitamin for at least one year prior to conceiving was linked with a 70 percent lower risk of delivering between 20 and 28 weeks and a 50 percent lower risk of delivering between 28 and 32 weeks (Bukowski & others, 2008). Also, as indicated earlier in the chapter, a lack of folic acid is related to neural tube defects in offspring, such as spina bifida (a defect in the spinal cord) (Li & others, 2018; Santos & others, 2016). And a recent research study in China found that folic acid supplementation during pregnancy reduced the risk of preterm birth (Liu & others, 2016). The U.S. Department of Health and Human Services (2018) recommends that pregnant women consume a minimum of 400 micrograms of folic acid per day (about twice the amount the average woman gets in one day). Orange juice and spinach are examples of foods rich in folic acid.
Eating fish is often recommended as part of a healthy diet, but pollution has made many fish a risky choice for pregnant women (Lipp & others, 2017). Some fish contain high levels of mercury, which is released into the air both naturally and by industrial pollution. When mercury falls into the water it can become toxic and accumulate in large fish, such as shark, swordfish, king mackerel, and some species of large tuna (American Pregnancy Association, 2018; Mayo Clinic, 2018). Mercury is easily transferred across the placenta, and the embryo’s developing brain and nervous system are highly sensitive to the metal. Researchers have found that prenatal mercury exposure is linked to adverse outcomes, including reduced placental and fetal growth, miscarriage, preterm birth, and lower intelligence (Jeong & others, 2017).
Recently, the American Pregnancy Association (2018) revised its conclusions about fish consumption during pregnancy but continued to recommend avoiding fish with a high mercury content, such as tilefish from the Gulf of Mexico, swordfish, shark, and king mackerel. The association and the FDA now recommend that pregnant women increase their consumption of fish that have a low mercury content, such as salmon, shrimp, tilapia, and cod.
Maternal Age When possible harmful effects on the fetus and infant are considered, two maternal age groups are of special interest: adolescents and women 35 years and older (Gockley & others, 2016; Kingsbury, Plotnikova, & Najman, 2018). The mortality rate of infants born to adolescent mothers is double that of infants born to mothers in their twenties. Adequate prenatal care decreases the probability that a child born to an adolescent girl will have physical problems. However, adolescents are the least likely of women in all age groups to obtain prenatal assistance from clinics and health services.
Maternal age is also linked to risk for adverse pregnancy outcomes. When a pregnant woman is older than 35, there is an increased risk that her child will have Down syndrome (Jaruratanasirikul & others, 2017). An individual with Down syndrome has distinctive facial characteristics, short limbs, intellectual disability, and motorPage 87 difficulties. A baby with Down syndrome rarely is born to a mother 16 to 34 years of age. However, when the mother reaches 40 years of age, the probability is slightly over 1 in 100 that a baby born to her will have Down syndrome, and by age 50 it is almost 1 in 10. When mothers are 35 years and older, risks also increase for low birth weight, preterm delivery, and fetal death (Koo & others, 2012; Mbugua Gitau & others, 2009). Also, in two recent studies, very advanced maternal age (40 years and older) was linked to adverse perinatal outcomes, including spontaneous abortion, preterm birth, stillbirth, and fetal growth restriction (Traisrisilp & Tongsong, 2015; Waldenstrom & others, 2015).
We still have much to learn about the influence of the mother’s age on risks of adverse outcomes during pregnancy and childbirth. As women remain active, exercise regularly, and are careful about their nutrition, their reproductive systems may remain healthier at older ages than was thought possible in the past.
What are some of the risks for infants born to adolescent mothers?
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Emotional States and Stress When a pregnant woman experiences intense fears, anxieties, and other emotions or negative mood states, physiological changes occur that may affect her fetus (Fatima, Srivastav, & Mondal, 2017). A mother’s stress may also influence the fetus indirectly by increasing the likelihood that the mother will engage in unhealthy behaviors such as taking drugs and receiving poor prenatal care.
High maternal anxiety and stress during pregnancy can have long-term consequences for the offspring (Isgut & others, 2017; Pinto & others, 2017). One study found that high levels of depression, anxiety, and stress during pregnancy were linked to internalizing problems in adolescence (Betts & others, 2014). A research review indicated that pregnant women with high levels of stress are at increased risk for having a child with emotional or cognitive problems, attention deficit hyperactivity disorder (ADHD), and language delay (Taige & others, 2007). Maternal emotions and stress also can influence the fetus indirectly by increasing the likelihood that the mother will engage in unhealthy behaviors such as taking drugs and receiving inadequate prenatal care. Further, a recent research review concluded that regardless of the form of maternal prenatal stress or anxiety and the prenatal trimester in which the stress or anxiety occurred, during the first two years of life their offspring displayed lower levels of self-regulation (Korja & others, 2017).
Maternal depression can have an adverse effect on birth outcomes and children’s development (Park & others, 2018). A research review concluded that maternal depression during pregnancy is linked to preterm birth (Mparmpakas & others, 2013), and another study linked maternal depression during pregnancy to low birth weight in full-term offspring (Chang & others, 2014). Another study revealed that maternal depression during pregnancy was related to increased risk for depression in offspring at age 18 (Pearson & others, 2013). Also, a recent study found that taking antidepressants early in pregnancy was linked to an increased risk of miscarriage (Almeida & others, 2016). In another study, when fetuses was exposed to serotonin-based antidepressants, they were more likely to be born preterm (Podrebarac & others, 2017). Further, a recent study revealed that taking antidepressants in the second or third trimesters of pregnancy was linked to an increased risk of autism spectrum disorders in children (Boukhris & others, 2016).
Paternal Factors So far, we have discussed how characteristics of the mother—such as drug use, disease, diet and nutrition, age, and emotional states—can influence prenatal development and the development of the child. Might there also be some paternal risk factors? Indeed, there are several (Sigman, 2017). Men’s exposure to lead, radiation, certain pesticides, and petrochemicals may cause abnormalities in sperm that lead to miscarriage or to diseases such as childhood cancer (Cordier, 2008). The father’s smoking during the mother’s pregnancy also can cause problems for the offspring (Han & others, 2015). A recent research review concluded that tobacco smoking is linked to impaired male fertility, as well as increased DNA damage, aneuploidy (abnormal number of chromosomes in a cell), and mutations in sperm (Beal, Yauk, & Marchetti, 2017). Also, in one study, heavy paternal smoking was associated with the risk of early pregnancy loss (Venners & others, 2004). This negative outcome may be related to the effects of secondhand smoke. And in another study, paternal smoking around the time of the child’s conception was linked to an increased risk of the child developing leukemia (Milne & others, 2012). Researchers have found that increasingPage 88 paternal age decreases the success rate of in vitro fertilization and increases the risk of preterm birth (Sharma & others, 2015). Also, a research review concluded that there is an increased risk of spontaneous abortion, autism, and schizophrenic disorders when the father is 40 years of age or older (Reproductive Endocrinology and Infertility Committee & others, 2012). A research study revealed that children born to fathers who were 40 years of age or older had increased risk of developing autism because of higher rates of random gene mutations in the older fathers (Kong & others, 2012). However, the age of the mother was not linked to development of autism in children.
How do pregnant women’s emotional states and stress levels affect prenatal development and birth?
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Another way that the father can influence prenatal and birth outcomes is through his relationship with the mother. By being supportive, helping with chores, and having a positive attitude toward the pregnancy, the father can improve the physical and psychological well-being of the mother. Conversely, a conflictual relationship with the mother is likely to bring adverse outcomes (Molgora & others, 2018). For example, a recent study found that intimate partner violence increased the mother’s stress level (Fonseca-Machado Mde & others, 2015).
In a study in China, the longer fathers smoked, the greater the risk that their children would develop cancer (Ji & others, 1997). What are some other paternal factors that can influence the development of the fetus and the child?
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PRENATAL CARE
Although prenatal care varies enormously, it usually involves a defined schedule of visits for medical care, which typically includes screening for manageable conditions and treatable diseases that can affect the baby or the mother (Flanagan & others, 2018; Goldenberg & McClure, 2018; Jarris & others, 2017; Sheeder & Weber Yorga, 2017). In addition to medical care, prenatal programs often include comprehensive educational, social, and nutritional services (Yeo, Crandell, & Jones-Vessey, 2016).
An increasing number of studies are finding that exercise either benefits the mother’s health and has positive neonatal outcomes or that there are no differences in outcomes (Barakat & others, 2017; Huang & others, 2017). Exercise during pregnancy helps prevent constipation, conditions the body, reduces the likelihood of excessive weight gain, lowers the risk of developing hypertension, improves immune system functioning, and is associated with a more positive mental state, including reduced levels of stress and depression (Bacchi & others, 2017; Barakat & others, 2016; Magro-Malosso & others, 2017; Marques & others, 2015). For example, a recent study found that two weekly 70-minute yoga sessions reduced pregnant women’s stress and enhanced their immune system functioning (Chen & others, 2017).
Exercise during pregnancy can also have positive benefits for offspring. For example, a recent study revealed that regular exercise by pregnant women was linked to more advanced development of the neonatal brain (Laborte-Lemoyne, Currier, & Ellenberg, 2017).
Does prenatal care matter? Information about pregnancy, labor, delivery, and caring for the newborn can be especially valuable for first-time mothers (Liu & others, 2017; Yun & others, 2014). Prenatal care is also very important for women in poverty and immigrant women because it links them with other social services (Gabbe & others, 2018; Kim & others, 2018; Mazul, Salm Ward, & Ngui, 2017).
How might a woman’s exercise during pregnancy benefit her and her offspring?
©Tracy Frankel/The Image Bank/Getty Images
An innovative program that is rapidly expanding in the United States is CenteringPregnancy (Chae & others, 2017; Heberlein & others, 2016; Liu & others, 2017). This program is relationship-centered and provides complete prenatal care in a group setting. CenteringPregnancy replaces traditional 15-minute physician visits with 90-minute peer group support settings and self-examination led by a physician or certified nurse-midwife. Groups of up to 10 women (and often their partners) meet regularly beginning at 12 to 16 weeks of pregnancy. The sessions emphasize empowering women to play an active role in experiencing a positive pregnancy. One study revealed that CenteringPregnancy groups made more prenatal visits, had higher breast feeding rates, and were more satisfied with their prenatal care than women in individual care (Klima & others, 2009). In a research review, participation in CenteringPregnancy increased breast feeding initiation by 53 percent overall and by 71 percent in African American womenPage 89 (Robinson, Garnier-Villarreal, & Hanson, 2018). Also, a recent study of adolescent mothers revealed that CenteringPregnancy was successful in getting participants to attend meetings, have appropriate weight gain, increase the use of highly effective contraceptive methods, and increase breast feeding (Trotman & others, 2015). And research has revealed that CenteringPregnancy group prenatal care is associated with reduced rates of preterm birth (Novick & others, 2013), as well as reduced rates of low birth weight and placement in a neonatal intensive care unit (Crockett & others, 2017; Gareau & others, 2016).
NORMAL PRENATAL DEVELOPMENT
Much of our discussion so far in this chapter has focused on what can go wrong with prenatal development. Prospective parents should take steps to avoid the vulnerabilities to fetal development that we have described. But it is important to keep in mind that most of the time, prenatal development does not go awry, and development occurs along the positive path that we described at the beginning of the chapter.
The increasingly popular CenteringPregnancy program alters routine prenatal care by bringing women out of exam rooms and into relationship-oriented groups.
©MBI/Alamy Stock Photo
Review Connect Reflect
LG1 Describe prenatal development.
Review
- What is the course of prenatal development?
- What is teratology, and what are some of the main threats to prenatal development?
- What are some good prenatal care strategies?
- Why is it important to take a positive approach to prenatal development?
Connect
- We have discussed chromosomal and gene-linked abnormalities that can affect prenatal development. How are the symptoms of the related conditions or risks similar to or different from those caused by teratogens or other hazards?
Reflect Your Own Personal Journey of Life
- If you are a woman, imagine that you have just found out that you are pregnant. What health-enhancing strategies will you follow during the prenatal period? If you are not a woman, imagine that you are the partner of a woman who has just found out she is pregnant. What will be your role in increasing the likelihood that the prenatal period will go smoothly?
2 Birth
LG2 Describe the birth process.
The Birth Process
Assessing the Newborn
Preterm and Low Birth Weight Infants
Nature writes the basic script for how birth occurs, but parents make important choices about conditions surrounding birth. We look first at the sequence of physical stages that occur when a child is born.
There was a star danced, and under that I was born.
—William Shakespeare
English Playwright, 17th Century
THE BIRTH PROCESS
The birth process occurs in stages, takes place in different contexts, and in most cases involves one or more attendants.
Stages of Birth The birth process occurs in three stages. The first stage is the longest of the three. Uterine contractions are 15 to 20 minutes apart at the beginning and last up to a minute. These contractions cause the woman’s cervix to stretch and open. As the first stage progresses, the contractions come closer togetherPage 90, appearing every two to five minutes. Their intensity increases. By the end of the first birth stage, contractions dilate the cervix to an opening of about 10 centimeters (4 inches), so that the baby can move from the uterus to the birth canal. For a woman having her first child, the first stage lasts an average of 6 to 12 hours; for subsequent children, this stage typically is much shorter.
After the long journey of prenatal development, birth takes place. During birth the baby is on a threshold between two worlds. What is the fetus/newborn transition like?
©ERproductions Ltd/Getty Images
The second birth stage begins when the baby’s head starts to move through the cervix and the birth canal. It terminates when the baby completely emerges from the mother’s body. With each contraction, the mother bears down hard to push the baby out of her body. By the time the baby’s head is out of the mother’s body, the contractions come almost every minute and last for about a minute. This stage typically lasts approximately 45 minutes to an hour.
Afterbirth is the third stage, at which time the placenta, umbilical cord, and other membranes are detached and expelled. This final stage is the shortest of the three birth stages, lasting only minutes.
Childbirth Setting and Attendants In 2015 in the United States, 98.5 percent of births took place in hospitals (Martin & others, 2017). Of the 1.5 percent of births occurring outside of a hospital, 63 percent took place in homes and almost 31 percent in free-standing birthing centers. The percentage of U.S. births at home is the highest since reporting of this context began in 1989. This increase in home births has occurred mainly among non-Latino White women, especially those who were older and married. For these non-Latino White women, two-thirds of their home births are attended by a midwife.
The people who help a mother during birth vary across cultures. In U.S. hospitals, it has become the norm for fathers or birth coaches to remain with the mother throughout labor and delivery. In the East African Nigoni culture, men are completely excluded from the childbirth process. When a woman is ready to give birth, female relatives move into the woman’s hut and the husband leaves, taking his belongings (clothes, tools, weapons, and so on) with him. He is not permitted to return until after the baby is born. In some cultures, childbirth is an open, community affair. For example, in the Pukapukan culture in the Pacific Islands, women give birth in a shelter that is open for villagers to observe.
In India, a midwife checks on the size, position, and heartbeat of a fetus. Midwives deliver babies in many countries around the world. What are some cultural variations in prenatal care?
©Viviane Moos/Corbis/Getty Images
Midwives Midwifery is a profession that provides health care to women during pregnancy, birth, and the postpartum period (Christensen & Overgaard, 2017; Cohen, Sumersille, & Friedman, 2018; Faucher, 2018). Midwives also may give women information about reproductive health and annual gynecological examinations. They may refer women to general practitioners or obstetricians if a pregnant woman needs medical care beyond a midwife’s expertise and skill.
Midwifery is practiced in most countries throughout the world (Arabi & others, 2018; Miyake & others, 2017). In Holland, more than 40 percent of babies are delivered by midwives rather than doctors. However, in the United States, recently only 8 percent of all hospital births in the United States were attended by a midwife (Martin & others, 2017). Nonetheless, the 8 percent figure represents a substantial increase from less than 1 percent in 1975. A research review concluded that for low-risk women, midwife-led care was characterized by a reduction in procedures during labor and increased satisfaction with care (Sutcliffe & others, 2012). Also, in this study no adverse outcomes were found for midwife-led care compared with physician-led care.
Doulas In some countries, a doula attends a childbearing woman. Doula is a Greek word that means “a woman who helps.” A doula is a caregiver who provides continuous physical, emotional, and educational support for the mother before, during, and after childbirth (McLeish & Redshaw, 2018). Doulas remain with the parents throughout labor, assessing and responding to the mother’s needs. Researchers have found positive effects when a doula is present at the birth of a child (Wilson & others, 2017). One study found that doula-assisted mothers were four times less likely to have a low birth weight baby and two times less likely to have experienced a birth complication involving themselves or their babyPage 91 (Gruber, Cupito, & Dobson, 2013). Another study revealed that for Medicaid recipients the odds of having a cesarean delivery were 41 percent lower for doula-supported births in the United States (Kozhimmanil & others, 2013). Thus, increasing doula-supported births could substantially lower the cost of a birth by reducing cesarean rates.
In the United States, most doulas work as independent providers hired by the expectant parents. Doulas typically function as part of a “birthing team,” serving as an adjunct to the midwife or the hospital’s obstetrical staff.
Methods of Childbirth U.S. hospitals often allow the mother and her obstetrician a range of options regarding the method of delivery. Key choices involve the use of medication, whether to use any of a number of nonmedicated techniques to reduce pain, and when to have a cesarean delivery.
Medication Three basic kinds of drugs that are used for labor are analgesia, anesthesia, and oxytocin/Pitocin.
Analgesia is used to relieve pain. Analgesics include tranquilizers, barbiturates, and narcotics (such as Demerol).
Anesthesia is used in late first-stage labor and during delivery to block sensation in an area of the body or to block consciousness. There is a trend toward not using general anesthesia, which blocks consciousness, in normal births because general anesthesia can be transmitted through the placenta to the fetus (Edwards & Jackson, 2017). An epidural block is regional anesthesia that numbs the woman’s body from the waist down. A research review concluded that epidural analgesia provides effective pain relief but increases the likelihood of having to use instruments during vaginal birth (Jones & others, 2012). Researchers are continuing to explore safer drug mixtures for use at lower doses to improve the effectiveness and safety of epidural anesthesia (Kobayashi & others, 2017; Wilson & others, 2018).
Oxytocin is a hormone that promotes uterine contractions; a synthetic form called Pitocin® is widely used to decrease the duration of the first stage of labor. The relative benefits and risks of administering synthetic forms of oxytocin during childbirth continue to be debated (Carlson, Corwin, & Lowe, 2017).
Predicting how a drug will affect an individual woman and her fetus is difficult (Ansari & others, 2016). A particular drug might have only a minimal effect on one fetus yet have a much stronger effect on another. The drug’s dosage also is a factor (Rankin, 2017). Stronger doses of tranquilizers and narcotics given to decrease the mother’s pain potentially have a more negative effect on the fetus than mild doses. It is important for the mother to assess her level of pain and have a voice in deciding whether she receives medication.
Natural and Prepared Childbirth For a brief time not long ago, the idea of avoiding all medication during childbirth gained favor in the United States. Instead, many women chose to reduce the pain of childbirth through techniques known as natural childbirth and prepared childbirth. Today, at least some medication is used in the typical childbirth, but elements of natural childbirth and prepared childbirth remain popular (Skowronski, 2015).
Natural childbirth is the method that aims to reduce the mother’s pain by decreasing her fear by providing information about childbirth and teaching her and her partner to use breathing methods and relaxation techniques during delivery (Bacon & Tomich, 2017; London & others, 2017). One type of natural childbirth that is used today is the Bradley Method, which involves husbands as coaches, relaxation for easier birth, and prenatal nutrition and exercise.
An instructor conducts a Lamaze class. What characterizes the Lamaze method?
©Barros & Barros/Getty Images
French obstetrician Ferdinand Lamaze developed a method similar to natural childbirth that is known as prepared childbirth, or the Lamaze method. It includes a special breathing technique to control pushing in the final stages of labor, as well as more detailed education about anatomy and physiology. The Lamaze method has become very popular in the United States (Podgurski, 2016). The pregnant woman’s partner usually serves as a coach who attends childbirth classes with her and helps with her breathing and relaxation during delivery.
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connecting with careers
Linda Pugh, Perinatal Nurse
Perinatal nurses work with childbearing women to support health and growth during the childbearing experience. Linda Pugh, Ph.D., R.N.C., is a perinatal nurse on the faculty at The Johns Hopkins University School of Nursing. She is certified as an inpatient obstetric nurse and specializes in the care of women during labor and delivery. She teaches undergraduate and graduate students, educates professional nurses, and conducts research. In addition, Pugh consults with hospitals and organizations about women’s health issues and topics we discuss in this chapter. Her research interests include nursing interventions with low-income breast-feeding women, ways to prevent and ameliorate fatigue during childbearing, and the use of breathing exercises during labor.
Courtesy of Linda Pugh
In sum, proponents of current natural and prepared childbirth methods conclude that when information and support are provided, women know how to give birth. To read about one nurse whose research focuses on fatigue during childbearing and breathing exercises during labor, see the Connecting with Careers profile. And to read about the wide variety of techniques now being used to reduce stress and control pain during labor, see Connecting Development to Life.
Cesarean Delivery In a cesarean delivery, the baby is removed from the mother’s uterus through an incision made in her abdomen. Cesarean deliveries are performed if the baby is lying crosswise in the uterus, if the baby’s head is too large to pass through the mother’s pelvis, if the baby develops complications, or if the mother is bleeding vaginally. Because of increased rates of respiratory complications, elective cesarean delivery is not recommended prior to 39 weeks of gestation unless there is an indication of fetal lung maturity (Greene, 2009). The benefits and risks of cesarean deliveries continue to be debated in the United States and around the world (Kupari & others, 2016; Ladewig, London, & Davidson, 2017). Some critics believe that too many babies are delivered by cesarean section in the United States (Blakey, 2011). The World Health Organization states that a country’s cesarean section rate should be 10 percent or less. The U.S. cesarean birth rate in 2015 was 32 percent, the lowest rate since 2007 (Martin & others, 2017). The highest cesarean rates are in the Dominican Republic and Brazil (56 percent); the lowest in New Zealand and the Czech Republic (26 percent) (McCullogh, 2016).
What are some of the specific reasons why physicians do a cesarean delivery? The most common reasons are failure to progress through labor (hindered by epidurals, for example) and fetal distress. Normally, the baby’s head comes through the vagina first. But if the baby is in a breech position, the baby’s buttocks are the first part to emerge from the vagina. In 1 of every 25 deliveries, the baby’s head is still in the uterus when the rest of the body is out. Breech births can cause respiratory problems. As a result, if the baby is in a breech position, a cesarean delivery is usually performed (Glavind & Uldbjerg, 2015).
ASSESSING THE NEWBORN
Almost immediately after birth, after the baby and its parents have been introduced, a newborn is taken to be weighed, cleaned up, and tested for signs of developmental problems that might require urgent attention. The Apgar Scale is widely used to assess the health of newborns at one and five minutes after birth. The Apgar Scale evaluates an infant’s heart rate, respiratory effort, muscle tone, body color, and reflex irritability. An obstetrician or a nurse does the evaluation and gives the newborn a score, or reading, of 0, 1, or 2 on each of these five health signs (see Figure 6). A total score of 7 to 10 indicates that the newborn’s condition is good. A score of 5 indicates there may be developmental difficulties. A score of 3 or below signals an emergency and indicates that the baby might not survive.
FIGURE 6 The Apgar Scale. A newborn’s score on the Apgar Scale indicates whether the baby has urgent medical problems. What are some trends in the Apgar scores of U.S. babies?
Source: Apgar, Virginia, “The Apgar Scale,” A Proposal for a New Method of Evaluation of the Newborn Infant, from Anesthesia and Analgesia, vol 32. New York: Lippincott, Williams & Wilkins, 1953.Page 93
connecting development to life
From Waterbirth to Music Therapy
The effort to reduce stress and control pain during labor has recently led to an increased use of older and newer nonmedicated techniques (Bindler & others, 2017; Cooper, Warland, & McCutcheon, 2018; Lewis & others, 2018a, b). These include waterbirth, massage, acupuncture, hypnosis, and music therapy.
What characterizes the use of waterbirth in delivering a baby?
Courtesy of Dr. Holly Beckwith
Waterbirth
Waterbirth involves giving birth in a tub of warm water. Some women go through labor in the water and get out for delivery; others remain in the water for delivery. The rationale for waterbirth is that the baby has been in an amniotic sac for many months and that delivery in a similar environment is likely to be less stressful for the baby and the mother (Kavosi & others, 2015). Mothers get into the warm water when contractions become closer together and more intense. Getting into the water too soon can cause labor to slow or stop. An increasing number of studies either show no differences in neonatal and maternal outcomes for waterbirth and non-waterbirth deliveries or positive outcomes for waterbirth (Davies & others, 2015; Taylor & others, 2016). For example, in a recent Swedish study, women who gave birth in water had a lower risk of vaginal tears, made quicker progress through the second stage of labor, needed fewer drugs for pain relief and interventions for medical problems, and rated their birth experience more positively than women who had conventional spontaneous vaginal births (Ulfsdottir, Saltvedt, & Georgsson, 2018). Waterbirth has been practiced more often in European countries such as Switzerland and Sweden in recent decades than in the United States but is increasingly being included in U.S. birth plans.
Massage
Massage is increasingly used prior to and during delivery (Frawley & others, 2016; Withers, Kharazmi, & Lim, 2018). Researchers have found that massage therapy reduces pain during labor (Gallo & others, 2018; Jones & others, 2012; Shahoei & others, 2017). For example, a recent study found that lower back massage reduced women’s labor pain and increased their satisfaction with the birth experience (Unalmis Erdogan, Yanikkerem, & Goker, 2018).
Acupuncture
Acupuncture, the insertion of very fine needles into specific locations in the body, is used as a standard procedure to reduce the pain of childbirth in China, although it only recently has begun to be used in the United States for this purpose (Jo & Lee, 2018; Mollart & others, 2018). Recent research indicates that acupuncture can have positive effects on labor and delivery (Akbarzadeh & others, 2015; Smith, Armour, & Ee, 2016). For example, in a recent study acupuncture was successful in reducing labor pain 30 minutes after the intervention (Allameh, Tehrani, & Ghasemi, 2015).
Hypnosis
Hypnosis, the induction of a psychological state of altered attention and awareness in which the individual is unusually responsive to suggestions, is also increasingly being used during childbirth (Howell, 2014; Mollart & others, 2018). Some studies have indicated positive effects of hypnosis for reducing pain during childbirth (Madden & others, 2016; McAllister & others, 2017).
Music Therapy
Music therapy during childbirth, which involves the use of music to reduce stress and manage pain, is becoming more common (Dehcheshmeh & Rafiel, 2015). More research is needed to determine its effectiveness (Laopaiboon & others, 2009).
What are some reasons that natural childbirth methods such as these might be chosen instead of medication?
The Apgar Scale is especially good at assessing the newborn’s ability to cope with the stress of delivery and the demands of a new environment (London & others, 2017). It also identifies high-risk infants who need resuscitation. One study revealed that compared with children who have a high Apgar score (9 to 10), the risk of developing attention deficit hyperactivityPage 94 disorder (ADHD) in childhood was 75 percent higher for newborns with a low Apgar score (1 to 4) and 63 percent higher for newborns with an Apgar score of 5 to 6 (Li, Olsen, & others, 2011). Recent studies have found that low Apgar scores are associated with long-term needs for additional support in education and decreased educational attainment (Tweed & others, 2016), increased risk of developmental vulnerability at 5 years of age (Razaz & others, 2016), and increased risk for developing ADHD (Hanc & others, 2016).
Another assessment of the newborn is the Brazelton Neonatal Behavioral Assessment Scale (NBAS), which is typically performed within 24 to 36 hours after birth. It is also used as a sensitive index of neurological competence up to one month after birth for typical infants and as a measure in many studies of infant development (Braithwaite & others, 2017). The NBAS assesses the newborn’s neurological development, reflexes, and reactions to people and objects.
A “kilogram kid,” weighing less than 2.3 pounds at birth. What are some long-term outcomes for weighing so little at birth?
©Diether Endlicher/AP Images
The NBAS is designed to assess normal, healthy, full-term infants. An “offspring” of the NBAS, the Neonatal Intensive Care Unit Network Neurobehavioral Scale (NNNS) provides another assessment of the newborn’s behavior, neurological and stress responses, and regulatory capacities (Aubuchon-Endsley & others, 2017; Spittle & others, 2017). The NBAS is especially designed to assess at-risk infants.
PRETERM AND LOW BIRTH WEIGHT INFANTS
Various conditions that pose threats for newborns have been given different labels. We will examine these conditions and discuss interventions for improving outcomes of preterm infants.
Preterm and Small for Date Infants Three related conditions pose threats to many newborns: low birth weight, being born preterm, and being small for date:
- Low birth weight infants weigh less than 5 pounds 8 ounces at birth. Very low birth weight newborns weigh less than 3 pounds 4 ounces, and extremely low birth weight newborns weigh less than 2 pounds.
- Preterm infants are those born three weeks or more before the pregnancy has reached its full term—in other words, before the completion of 37 weeks of gestation (the time between fertilization and birth).
- Small for date infants (also called small for gestational age infants) are those whose birth weight is below normal when the length of the pregnancy is considered. They weigh less than 90 percent of all babies of the same gestational age. Small for date infants may be preterm or full term. One study found that small for date infants had more than a fourfold increased risk of death (Regev & others, 2003).
In 2015, 9.6 percent of babies born in the United States werePage 95 born preterm (Martin & others, 2017). The preterm birth rate was 8.8 percent for non-Latino White infants, down from 11.4 percent in 2011 (Martin & others, 2017). In 2015, the preterm birth rate was 13.4 percent for African American infants (down from 16.7 percent in 2011) and 9.1 percent for Latino infants (down from 11.6 percent in 2011) (Martin & others, 2017).
Recently, considerable attention has been directed to the role that progestin (a synthetic hormone similar to progesterone) might play in reducing preterm births (Awwad & others, 2015; Iams & others, 2018). One study found that progestin treatment was associated with a decrease in preterm birth for women with a history of one or more spontaneous births (Markham & others, 2014). Increasing use of progestin and decreasing rates of smoking are among the factors that likely account for the recent decrease in preterm births (Schoen & others, 2015).
Might exercise during pregnancy reduce the likelihood of preterm birth? One study found that compared with sedentary pregnant women, women who engaged in light leisure time physical activity had a 24 percent reduced likelihood of preterm delivery and those who participated in moderate to heavy leisure time physical activity had a 66 percent reduced risk of preterm delivery (Hegaard & others, 2008).
The incidence of low birth weight varies considerably from country to country. In some countries, such as India and Sudan, where poverty is rampant and the health and nutrition of mothers are poor, the percentage of low birth weight babies reaches as high as 31 percent (see Figure 7). In the United States, there has been an increase in low birth weight infants in the last two decades, and the U.S. low birth weight rate of 9.6 percent in 2015 is considerably higher than that of many other developed countries (Martin & others, 2017). For example, only 4 percent of the infants born in Sweden, Finland, Norway, and South Korea are low birth weight, and only 5 percent of those born in New Zealand, Australia, and France are low birth weight.
FIGURE 7 Percentage of Infants Born with Low Birth Weight in Selected Countries
In both developed and developing countries, adolescents who give birth when their bodies have not fully matured are at risk for having low birth weight babies (Bird & others, 2017; Kirbas, Gulerman, & Daglar, 2016). In the United States, the increase in the number of low birth weight infants is due to factors such as drug use, poor nutrition, multiple births, reproductive technologies, and improved technology and prenatal care that result in more high-risk babies surviving (National Center for Health Statistics, 2012; Pereira & others, 2017). Poverty also continues to be a major factor in preterm births in the United States (Huynh & others, 2017; Wallace & others, 2016). Women living in poverty are more likely to be obese, have diabetes and hypertension, and to smoke cigarettes and use illicit drugs, and less likely to receive regular prenatal care (Timmermans & others, 2011).
developmental connection
Poverty
Poverty continues to negatively affect development throughout childhood. Connect to “Socioemotional Development in Early Childhood” and “Socioemotional Development in Middle and Late Childhood.”
Consequences of Preterm Birth and Low Birth Weight Although most preterm and low birth weight infants are healthy, as a group they have more health problems and developmental delays than normal birth weight infants (George & others, 2018; London & others, 2017). For preterm birth, the terms extremely preterm and very preterm are increasingly used (Ohlin & others, 2015). Extremely preterm infants are those born at less than 28 weeks gestation, and very preterm infants are those born at less than 33 weeks of gestational age. Figure 8 shows the results of a Norwegian study indicating that the earlier preterm infants are born, the more likely they are to drop out of school (Swamy, Ostbye, & Skjaerven, 2008).
FIGURE 8 Percentage of Preterm and Full-Term Infants Who Dropped Out of School
The number and severity of health problems increase when infants are born very early and as their birth weight decreases (Linsell & others, 2017; Pascal & others, 2018). Survival rates for infants who are born very early and very small have risen, but with this improved survival rate have come an increased rate of severe brain damage (Rogers & Hintz, 2018) and lower level of executive function, especially in working memory and planning (Burnett & others, 2018).
One study revealed that very preterm, low birth weight infants had abnormal axon development in their brains and impaired cognitive development at 9 years of age (Iwata & others, 2012). Children born low in birth weight are more likely than their normal birth weight counterparts to develop a learning disability, attention deficit hyperactivity disorder, autism spectrum disorders, or breathing problems such as asthma (Brinskma & others, 2017; Ng & others, 2017). Approximately 50 percent of all low birth weight children are enrolled in special education programs.
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Nurturing Low Birth Weight and Preterm Infants Two increasingly used interventions in the neonatal intensive care unit (NICU) are kangaroo care and massage therapy. Kangaroo care involves skin-to-skin contact in which the baby, wearing only a diaper, is held upright against the parent’s bare chest, much as a baby kangaroo is carried by its mother (Raajashri & others, 2018; Stockwell, 2017). Kangaroo care is typically practiced for two to three hours per day, skin-to-skin over an extended time in early infancy.
A new mother practices kangaroo care. What is kangaroo care?
©iStockphoto.com/casenbina
Why use kangaroo care with preterm infants? Preterm infants often have difficulty coordinating their breathing and heart rate, and the close physical contact with the parent provided by kangaroo care can help to stabilize the preterm infant’s heartbeat, temperature, and breathing (Boundy & others, 2017; Furman, 2017). Preterm infants who experience kangaroo care gain more weight than their counterparts who are not given this care (Sharma, Murki, & Oleti, 2018). Recent research also revealed that kangaroo care decreased pain in newborns (Johnston & others, 2017; Mooney-Leber & Brummelte, 2017). Further, a research review concluded that kangaroo care decreased the risk of mortality in low birth weight infants (Conde-Aguedelo, Belizan, & Diaz-Rossello, 2014). Also, a research study demonstrated the positive long-term benefits of kangaroo care (Feldman, Rosenthal, & Eidelman, 2014). In this study, maternal-newborn kangaroo care with preterm infants was linked to better respiratory and cardiovascular functioning, sleep patterns, and cognitive functioning from 6 months to 10 years of age. Further, in a longitudinal study, the nurturing positive effects of kangaroo care with preterm and low birth weight infants that were initially found for intelligence and home environment at one year of age were still positive 20 years later in emerging adults’ reduced school absenteeism, reduced hyperactivity, lower aggressiveness, and social skills (Charpak & others, 2017).
A survey conducted in the United States found that mothers were much more likely to have a positive view of kangaroo care and to believe it should be provided daily than were neonatal intensive care nurses (Hendricks-Munoz & others, 2013). There is concern that kangaroo care is not used as often as it could be used in neonatal intensive care units (Smith & others, 2017). Increasingly, kangaroo care is recommended as standard practice for all newborns (Johnston & others, 2017).
developmental connection
Attachment
A classic study with surrogate cloth and wire monkeys demonstrated the important role that touch plays in infant attachment. Connect to “Socioemotional Development in Infancy.”
Many adults will attest to the therapeutic effects of receiving a massage. In fact, many will pay a premium to receive one at a spa on a regular basis. But can massage play a role in improving the developmental outcomes for preterm infants? A study found that both kangaroo care and massage therapy were equally effective in improving body weight and reducing length of hospital stay for low birth weight infants (Rangey & Sheth, 2014). In another recent study, massage therapy improved the scores of HIV-exposed infants on both physical and mental scales, while also improving their hearing and speech (Perez & others, 2015). To read more about massage therapy, see Connecting Through Research.
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Review Connect Reflect
LG2 Describe the birth process.
Review
- What are the three main stages of birth? What are some examples of birth strategies? What is the transition from fetus to newborn like for the infant?
- What are three measures of neonatal health and responsiveness?
- What are the outcomes for children if they are born preterm or with a low birth weight?
Connect
- What correlations have been found between birth weight and country of birth, and what might the causes be?
Reflect Your Own Personal Journey of Life
- If you are a female, which birth strategy do you prefer? Why? If you are a male, how involved would you want to be in helping your partner during the birth of your baby? Explain.
connecting through research
How Does Massage Therapy Affect the Mood and Behavior of Babies?
Throughout history and in many cultures, caregivers have massaged infants. In Africa and Asia, infants are routinely massaged by parents or other family members for several months after birth. In the United States, interest in using touch and massage to improve the growth, health, and well-being of infants has been stimulated by the research of Tiffany Field, director of the Touch Research Institute at the University of Miami School of Medicine (Field, 2001, 2007, 2010b, 2017; Diego, Field, & Hernandez-Reif, 2008, 2014; Field, Diego, & Hernandez-Reif, 2008, 2010; Field & others, 2006).
In one study, preterm infants in a neonatal intensive care unit (NICU) were randomly assigned to a massage therapy group or a control group (Hernandez-Reif, Diego, & Field, 2007). For five consecutive days, the preterm infants in the massage group were given three 15-minute moderate-pressure massages. Behavioral observations of the following stress behaviors were made on the first and last days of the study: crying, grimacing, yawning, sneezing, jerky arm and leg movements, startles, and finger flaring. The various stress behaviors were summarized in a composite stress behavior index. As indicated in Figure 9, massage had a stress-reducing effect on the preterm infants, which is especially important because they encounter numerous stressors while they are hospitalized.
Tiffany Field massages a newborn infant. What types of infants have benefited from massage therapy?
Courtesy of Dr. Tiffany Field
In a research review of massage therapy with preterm infants, Field and her colleagues (Field, Hernandez-Reif, & Freedman, 2004) concluded that the most consistent findings involve two positive results: (1) increased weight gain and (2) discharge from the hospital from three to six days earlier.
FIGURE 9 Preterm Infants Show Reduced Stress Behaviors and Activity After Five Days of Massage Therapy
Source: Hernandez-Reif, M., Diego, M., & Field, T. “Preterm infants show reduced stress behaviors and activity after 5 days of massage therapy,” Infant Behavior and Development, 30, 2007, 557–561.
Infants are not the only ones who may benefit from massage therapy (Field, 2017). In other studies, Field and her colleagues have demonstrated the benefits of massage therapy with women in reducing labor pain (Field, Hernandez-Reif, Taylor, & others, 1997), with children who have asthma (Field, Henteleff, & others, 1998), with autistic children’s attentiveness (Field, Lasko, & others, 1997), and with adolescents who have attention deficit hyperactivity disorder (Field, Quintino, & others, 1998).
3 The Postpartum Period
LG3 Explain the changes that take place in the postpartum period.
Physical Adjustments
Emotional and Psychological Adjustments
Bonding
The weeks after childbirth present challenges for many new parents and their offspring. This is the postpartum period, the period after childbirth or delivery that lasts for about six weeks or until the mother’s body has completed its adjustment and has returned to a nearly prepregnant state. It is a time when the woman adjusts, both physicallyPage 98 and psychologically, to the process of childbearing.
The postpartum period involves a great deal of adjustment and adaptation (Doering & others, 2017). The adjustments needed are physical, emotional, and psychological.
PHYSICAL ADJUSTMENTS
A woman’s body makes numerous physical adjustments in the first days and weeks after childbirth (Neiterman & Fox, 2018). She may have a great deal of energy or feel exhausted and let down. Though these changes are normal, the fatigue can undermine the new mother’s sense of well-being and confidence in her ability to cope with a new baby and a new family life (Doering, Sims, & Miller, 2017).
A concern is the loss of sleep that the primary caregiver experiences in the postpartum period (McBean, Kinsey, & Montgomery-Downs, 2016). In the 2007 Sleep in America survey, a substantial percentage of women reported loss of sleep during pregnancy and in the postpartum period (National Sleep Foundation, 2007) (see Figure 10). The loss of sleep can contribute to stress, marital conflict, and impaired decision making (Meerlo, Sgoifo, & Suchecki, 2008). In a recent study, worsening or minimal improvement in sleep problems from 6 weeks to 7 months postpartum were associated with an increase in depressive symptoms (Lewis & others, 2018).
FIGURE 10 Sleep Deprivation in Pregnant and Postpartum Women
After delivery, a mother’s body undergoes sudden and dramatic changes in hormone production. When the placenta is delivered, estrogen and progesterone levels drop steeply and remain low until the ovaries start producing hormones again.
EMOTIONAL AND PSYCHOLOGICAL
ADJUSTMENTS
Emotional fluctuations are common for mothers in the postpartum period. For some women, emotional fluctuations decrease within several weeks after the delivery, but other women experience more long-lasting emotional swings (O’Hara & Engeldinger, 2018; Pawluski, Lonstein, & Fleming, 2017).
As shown in Figure 11, about 70 percent of new mothers in the United States have what are called the postpartum blues. About two to three days after birth, they begin to feel depressed, anxious, and upset. These feelings may come and go for several months after the birth, often peaking about three to five days after birth. Even without treatment, these feelings usually go away after one or two weeks.
FIGURE 11 Postpartum Blues and Postpartum Depression Among U.S. Women. Some health professionals refer to the postpartum period as the “fourth trimester.” Though the time span of the postpartum period does not necessarily cover three months, the term “fourth trimester” suggests the continuity and the importance of the first several months after birth for the mother and baby.
However, some women develop postpartum depression, which involves a major depressive episode that typically occurs about four weeks after delivery. Women with postpartum depression have such strong feelings of sadness, anxiety, or despair that for at least a two-week period they have trouble coping with their daily tasks. Without treatment, postpartum depression may become worse and last for many months (Di Florio & others, 2014). And many women with postpartum depression don’t seek help. For example, one study found that 15 percent of the women surveyed had postpartum depression symptoms but less than half had sought help (McGarry & others, 2009). Estimates indicate that 10 to 14 percent of new mothers experience postpartum depression.
A research review concluded that the following are risk factors for developing postpartum depression: a history of depression, depression and anxiety during pregnancy, neuroticism, low self-esteem, postpartum blues, poor marital relationship, and a low level of social support (O’Hara & McCabe, 2013). And another recent study revealed that women who had a history of depression were 20 times more likely to develop postpartum depression than women who had no history of depression (Silverman & others, 2017).
Several antidepressant drugs are effective in treating postpartum depression and appear to be safe for breast-feeding women (Howard, Mehta, & Powrie, 2017; Latendresse, Elmore, & Deneris, 2017). Psychotherapy, especially cognitive therapy, is effective in easing postpartum depression for many women (Dennis, 2017; O’Hara & Engeldinger, 2018). Also, engaging in regular exercise may help in treating postpartum depression (Gobinath & others, 2018; McCurdy & others, 2017). For example, a recent meta-analysis concluded that physical exercise during the postpartum period is a safe strategy to reduce postpartum depressive symptoms (Poyatos-Leon & others, 2017).
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connecting with careers
Diane Sanford, Clinical Psychologist and Postpartum Expert
Diane Sanford has a doctorate in clinical psychology, and for many years she had a private practice that focused on marital and family relationships. But after she began collaborating with a psychiatrist whose clients included women with postpartum depression, Dr. Sanford, along with a women’s health nurse, founded Women’s Healthcare Partnership in St. Louis, Missouri, which specialized in women’s adjustment during the postpartum period. Sanford (with Ann Dunnewold) authored Life Will Never Be the Same: The Real Mom’s Postpartum Survival Guide. She also is a medical expert for BabyCenter.com.
Diane Sanford is a leading expert on postpartum depression.Courtesy of Dr. Diane Sanford
For more information about what clinical psychologists do, see the Careers in Life-Span Development appendix.
A mother’s postpartum depression can affect the way she interacts with her infant (Kleinman & Reizer, 2018). A research review concluded that the interaction difficulties of depressed mothers and their infants occur across cultures and socioeconomic status groups, and encompass less sensitivity of the mothers and less responsiveness on the part of their infants (Field, 2010a). Several caregiving activities also are compromised, including feeding (especially breast feeding), sleep routines, and safety practices. In a recent study, postpartum depression was associated with an increase in 4-month-old infants’ unintentional injuries (Yamaoka, Fujiwara, & Tamiya, 2016). Further, a recent study revealed that mothers’ postpartum depression, but not generalized anxiety, were linked to their children’s emotional negativity and behavior problems at 2 years of age (Prenoveau & others, 2017). To read about one individual who specializes in women’s adjustment during the postpartum period, see Connecting with Careers.
Fathers also undergo considerable adjustment in the postpartum period, even when they work away from home all day (Shorey & others, 2017; Takehara & others, 2017). When the mother develops postpartum depression, many fathers also experience feelings of depression (Cameron & others, 2017; Sundstrom Poromaa & others, 2017). Many fathers feel that the baby comes first and gets all of the mother’s attention; some feel that they have been replaced by the baby. A recent study found that 5 percent of fathers had depressive symptoms in the first two weeks following delivery (Anding & others, 2016).
The postpartum period is a time of considerable adjustment and adaptation for both the mother and the father. Fathers can provide an important support system for mothers, especially in helping mothers care for young infants. What kinds of tasks might the father of a newborn do to support the mother?
©Howard Grey/Getty Images
The father’s support and caring can play a role in whether the mother develops postpartum depression (Kumar, Oliffe, & Kelly, 2018). One study revealed that higher support by fathers was related to a lower incidence of postpartum depression in women (Smith & Howard, 2008). Also, a recent study found that depressive symptoms in both the mother and father were associated with impaired bonding with their infant during the postpartum period (Kerstis & others, 2016).
BONDING
A special component of the parent-infant relationship is bonding, the formation of a connection, especially a physical bond between parents and the newborn in the period shortly after birth. Sometimes hospitals seem determined to deter bonding. Drugs given to the mother to make her delivery less painful can makePage 100 the mother drowsy, interfering with her ability to respond to and stimulate the newborn. Mothers and newborns are often separated shortly after delivery, and preterm infants are isolated from their mothers even more than full-term infants.
developmental connection
Attachment
Konrad Lorenz demonstrated the importance of early bonding in greylag geese, but the first few days of life are unlikely to be a critical period for bonding in human infants. Connect to “Introduction.”
Do these practices do any harm? Some physicians believe that during the period shortly after birth, the parents and newborn need to form an emotional attachment as a foundation for optimal development in years to come (Kennell, 2006; Kennell & McGrath, 1999). Is there evidence that close contact between mothers and babies in the first several days after birth is critical for optimal development later in life? Although some research supports this bonding hypothesis (Klaus & Kennell, 1976), a body of research challenges the significance of the first few days of life as a critical period (Bakeman & Brown, 1980; Rode & others, 1981). Indeed, the extreme form of the bonding hypothesis—that the newborn must have close contact with the mother in the first few days of life to develop optimally—simply is not true.
Nonetheless, the weakness of the bonding hypothesis should not be used as an excuse to keep motivated mothers from interacting with their newborns. Such contact brings pleasure to many mothers. In some mother-infant pairs—including preterm infants, adolescent mothers, and mothers from disadvantaged circumstances—early close contact may establish a climate for improved interaction after the mother and infant leave the hospital.
Many hospitals now offer a rooming-in arrangement, in which the baby remains in the mother’s room most of the time during its hospital stay. However, if parents choose not to use this rooming-in arrangement, the weight of the research suggests that this decision will not harm the infant emotionally (Lamb, 1994).
Review Connect Reflect
LG3 Explain the changes
that take place in the postpartum period.
Review
- What does the postpartum period involve? What physical adjustments does the woman’s body make during this period?
- What emotional and psychological adjustments characterize the postpartum period?
- Is bonding critical for optimal development?
Connect
- Compare and contrast what you learned about kangaroo care and breast feeding of preterm infants with what you learned about bonding and breast feeding when the mother is suffering from postpartum depression.
Reflect Your Own Personal Journey of Life
- If you are a female, what can you do to adjust effectively in the postpartum period? If you are a male, what can you do to help your partner during the postpartum period?
topical connections looking forward
This chapter marks the beginning of our chronological look at the journey of life. In the next three chapters, we will follow the physical, cognitive, and socioemotional development of infants, including the theories, research, and milestones associated with the first 18 to 24 months of life. You will learn about the remarkable and complex physical development of infants’ motor skills, such as learning to walk; trace the early development of infants’ cognitive skills, such as the ability to form concepts; and explore infants’ surprisingly sophisticated socioemotional capabilities, as reflected in the development of their motivation to share and to perceive others’ actions as intentionally motivated.
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reach your learning goals
Prenatal Development and Birth
1 Prenatal Development
LG1 Describe prenatal development.
The Course of Prenatal Development
Teratology and Hazards to Prenatal Development
Prenatal Care
Normal Prenatal Development
- Prenatal development is divided into three periods: germinal (conception until 10 to 14 days later), which ends when the zygote (a fertilized egg) attaches to the uterine wall; embryonic (two to eight weeks after conception), during which the embryo differentiates into three layers, life-support systems develop, and organ systems form (organogenesis); and fetal (from two months after conception until about nine months, or when the infant is born), a time when organ systems have matured to the point at which life can be sustained outside the womb.
- The growth of the brain during prenatal development is nothing short of remarkable. By the time babies are born, they have approximately 100 billion neurons, or nerve cells. Neurogenesis is the term for the formation of new neurons. The nervous system begins with the formation of a neural tube at 18 to 24 days after conception. Proliferation and migration are two processes that characterize brain development in the prenatal period. The basic architecture of the brain is formed in the first two trimesters of prenatal development.
- Teratology is the field of study that investigates the causes of congenital (birth) defects. Any agent that causes birth defects is called a teratogen. The dose, genetic susceptibility, and time of exposure influence the severity of the damage to an unborn child and the type of defect that occurs.
- Prescription drugs that can be harmful include antibiotics. Nonprescription drugs that can be harmful include diet pills, aspirin, and caffeine. Legal psychoactive drugs that are potentially harmful to prenatal development include alcohol and nicotine.
- Fetal alcohol spectrum disorders are a cluster of abnormalities that appear in offspring of mothers who drink heavily during pregnancy. Even when pregnant women drink moderately (one to two drinks a few days a week), negative effects on their offspring have been found.
- Cigarette smoking by pregnant women has serious adverse effects on prenatal and child development, including low birth weight. Illegal psychoactive drugs that are potentially harmful to offspring include marijuana, cocaine, and heroin. Incompatibility of the mother’s and the father’s blood types can also be harmful to the fetus.
- Environmental hazards include radiation, environmental pollutants, and toxic wastes. Syphilis, rubella (German measles), genital herpes, and AIDS are infectious diseases that can harm the fetus.
- Other parental factors that affect prenatal development include maternal diet and nutrition, age, emotional states and stress, and paternal factors. A developing fetus depends entirely on its mother for nutrition. Maternal age can negatively affect the offspring’s development if the mother is an adolescent or over 35. High stress in the mother is linked with less than optimal prenatal and birth outcomes. Paternal factors that can adversely affect prenatal development include exposure to lead, radiation, certain pesticides, and petrochemicals, as well as smoking.
- Prenatal care varies extensively but usually involves health maintenance services with a defined schedule of visits.
- It is important to remember that, although things can go wrong during pregnancy, most of the time pregnancy and prenatal development go well.
2 Birth
LG2 Describe the birth process.
The Birth Process
Assessing the Newborn
Preterm and Low Birth Weight Infants
- Childbirth occurs in three stages. The first stage, which lasts about 6 to 12 hours for a woman having her first child, is the longest stage. The cervix dilates to about 10 centimeters (4 inches) by the end of the first stage. The second stage begins when the baby’s head starts to move through the cervix and ends with the baby’s complete emergence. The third stagePage 102 involves the delivery of the placenta after birth. Childbirth strategies involve the childbirth setting and attendants.
- In many countries, a doula attends a childbearing woman. Methods of delivery include medicated, natural or prepared, and cesarean.
- For many years, the Apgar Scale has been used to assess the newborn’s health. The Brazelton Neonatal Behavioral Assessment Scale examines the newborn’s neurological development, reflexes, and reactions to people. Recently, the Neonatal Intensive Care Unit Network Neurobehavioral Scale (NNNS) was created to assess at-risk infants.
- Low birth weight infants weigh less than 5 pounds 8 ounces, and they may be preterm (born before the completion of 37 weeks of gestation) or small for date (also called small for gestational age, which refers to infants whose birth weight is below normal when the length of pregnancy is considered). Small for date infants may be preterm or full term. Although most low birth weight and preterm infants are normal and healthy, as a group they have more health problems and developmental delays than normal birth weight infants. Kangaroo care and massage therapy have been shown to have benefits for preterm infants.
3 The Postpartum Period
LG3 Explain the changes that take place in the postpartum period.
Physical Adjustments
Emotional and
Psychological Adjustments
Bonding
- The postpartum period is the name given to the period after childbirth or delivery. The period lasts for about six weeks or until the woman’s body has completed its adjustment. Physical adjustments in the postpartum period include fatigue and hormonal changes.
- Emotional fluctuations on the part of the mother are common in this period, and they can vary a great deal from one mother to the next. Postpartum depression characterizes women who have such strong feelings of sadness, anxiety, or despair that they have trouble coping with daily tasks in the postpartum period. Postpartum depression occurs in about 10 percent of new mothers. The father also goes through a postpartum adjustment.
- Bonding is the formation of a close connection, especially a physical bond between parents and the newborn shortly after birth. Early bonding has not been found to be critical in the development of a competent infant.
key terms
Brazelton Neonatal Behavioral Assessment Scale (NBAS)
fetal alcohol spectrum disorders (FASD)
Neonatal Intensive Care Unit Network Neurobehavioral Scale (NNNS)
key people
- Berry Brazelton
Tiffany Field
Ferdinand Lamaze
chapter 4
PHYSICAL DEVELOPMENT IN INFANCY
chapter outline
1 Physical Growth and Development in Infancy
Learning Goal 1 Discuss physical growth and development in infancy.
Learning Goal 2 Describe infants’ motor development.
3 Sensory and Perceptual Development
Learning Goal 3 Summarize the course of sensory and perceptual development in infancy.
What Are Sensation and Perception?
Nature, Nurture, and Perceptual Development
©Image Source/Getty Images
Latonya is a newborn baby inPage 105 Ghana. During her first days of life, she has been kept apart from her mother and bottle fed. Manufacturers of infant formula provide the hospital where she was born with free or subsidized milk powder. Her mother has been persuaded to bottle feed rather than breast feed her. When her mother bottle feeds Latonya, she overdilutes the milk formula with unclean water. Latonya’s feeding bottles have not been sterilized. Latonya becomes very sick. She dies before her first birthday.
Ramona was born in a Nigerian hospital with a “baby-friendly” program. In this program, babies are not separated from their mothers when they are born, and the mothers are encouraged to breast feed them. The mothers are told of the perils that bottle feeding can bring because of unsafe water and unsterilized bottles. They also are informed about the advantages of breast milk, which include its nutritious and hygienic qualities, its ability to immunize babies against common illnesses, and the role of breast feeding in reducing the mother’s risk of breast and ovarian cancer. Ramona’s mother is breast feeding her. At 1 year of age, Ramona is very healthy.
(Top) An HIV-infected mother breast feeding her baby in Nairobi, Kenya. (Bottom) A Rwandan mother bottle feeding her baby. What are some concerns about breast versus bottle feeding in impoverished African countries?(Top) ©Wendy Stone/Corbis/Getty Images;
(bottom) ©Dave Bartruff/Corbis/Getty Images
For many years, maternity units in hospitals favored bottle feeding and did not give mothers adequate information about the benefits of breast feeding. In recent years, the World Health Organization and UNICEF have tried to reverse the trend toward bottle feeding of infants in many impoverished countries. They instituted “baby-friendly” programs in many countries (Grant, 1993). They also persuaded the International Association of Infant Formula Manufacturers to stop marketing their baby formulas to hospitals in countries where the governments support the baby-friendly initiatives (Grant, 1993). For the hospitals themselves, costs actually were reduced as infant formula, feeding bottles, and separate nurseries became unnecessary. For example, baby-friendly Jose Fabella Memorial Hospital in the Philippines reported saving 8 percent of its annual budget. Still, there are many places in the world where the baby-friendly initiatives have not been implemented.
The advantages of breast feeding in impoverished countries are substantial (UNICEF, 2017). However, these advantages must be balanced against the risk of passing the human immunodeficiency virus (HIV) to babies through breast milk if the mothers have the virusPage 106 (Croffut & others, 2018; Mnyani & others, 2017; Wojcicki, 2017). In some areas of Africa, more than 30 percent of mothers have HIV, but the majority of these mothers don’t know that they are infected (Mepham, Bland, and Newell, 2011). Later in the chapter, in the section on nutrition, we will look more closely at recent research on breast feeding in the United States, outlining the benefits for infants and mothers and discussing several life-threatening diseases that infants can contract as a result of malnutrition.
topical connections looking back
Previously, we followed the physical development that takes place from fertilization through the germinal, embryonic, and fetal periods of prenatal development. We learned that by the time the fetus has reached full gestational age (approximately 40 weeks), it has grown from a fertilized egg, barely visible to the human eye, to a fully formed human weighing approximately 8 pounds and measuring 20 inches in length. Also remarkable is the fact that by the end of the prenatal period the brain has developed approximately 100 billion neurons.
preview
It is very important for infants to get a healthy start. When they do, their first two years of life are likely to be a time of amazing development. In this chapter, we focus on the biological domain and the infant’s physical development, exploring physical growth, motor development, and sensory and perceptual development.
1 Physical Growth and Development
in Infancy
LG1 Discuss physical growth and development in infancy.
Patterns of Growth
Height and Weight
The Brain
Sleep
Nutrition
Infants’ physical development in the first two years of life is extensive. Newborns’ heads are quite large in comparison with the rest of their bodies. They have little strength in their necks and cannot hold their heads up, but they have some basic reflexes. In the span of 12 months, infants become capable of sitting anywhere, standing, stooping, climbing, and usually walking. During the second year, growth decelerates, but rapid increases in such activities as running and climbing take place. Let’s now examine in greater detail the sequence of physical development in infancy.
A baby is the most complicated object made by unskilled labor.
—Anonymous
PATTERNS OF GROWTH
An extraordinary proportion of the total body is occupied by the head during prenatal development and early infancy (see Figure 1). The cephalocaudal pattern is the sequence in which the earliest growth always occurs at the top—the head—with physical growth and differentiation of features gradually working their way down from top to bottom (for example, shoulders, middle trunk, and so on). This same pattern occurs in the head area,Page 107 because the top parts of the head—the eyes and brain—grow faster than the lower parts, such as the jaw.
FIGURE 1 CHANGES IN PROPORTIONS OF THE HUMAN BODY DURING GROWTH. As individuals develop from infancy through adulthood, one of the most noticeable physical changes is that the head becomes smaller in relation to the rest of the body. The fractions listed refer to head size as a proportion of total body length at different ages.
Motor development generally proceeds according to the cephalocaudal principle. For example, infants see objects before they can control their torso, and they can use their hands long before they can crawl or walk. However, development does not follow a rigid blueprint. One study found that infants reached for toys with their feet prior to reaching with their hands (Galloway & Thelen, 2004). On average, infants first touched the toy with their feet when they were 12 weeks old and with their hands when they were 16 weeks old.
Growth also follows the proximodistal pattern, the sequence in which growth starts at the center of the body and moves toward the extremities. For example, infants control the muscles of their trunk and arms before they control their hands and fingers, and they use their whole hands before they can control several fingers (Bindler & others, 2017).
HEIGHT AND WEIGHT
The average North American newborn is 20 inches long and weighs 7.6 pounds. Ninety-five percent of full-term newborns are 18 to 22 inches long and weigh between 5 and 10 pounds.
In the first several days of life, most newborns lose 5 to 7 percent of their body weight before they adjust to feeding by sucking, swallowing, and digesting. Then they grow rapidly, gaining an average of 5 to 6 ounces per week during the first month. They have doubled their birth weight by the age of 4 months and have nearly tripled it by their first birthday. By their first birthday, infants’ length has increased to an average of 30 inches.
Growth slows considerably in the second year of life (London & others, 2017). By 2 years of age, infants weigh approximately 26 to 32 pounds, having gained a quarter to half a pound per month during the second year to reach about one-fifth of their adult weight. At 2 years of age, infants average 32 to 35 inches in height, which is nearly half of their adult height.
An important point about growth is that it often is not smooth and continuous but rather is episodic, occurring in spurts (Adolph, 2018; Adolph & Berger, 2015). In infancy, growth spurts may occur in a single day and alternate with long time frames characterized by little or no growth for days and weeks (Lampl & Johnson, 2011; Lampl & Schoen, 2018). In two analyses, in a single day, infants grew seven-tenths of an inch in length in a single day (Lampl, 1993) and their head circumference increased three-tenths of an inch (Caino & others, 2010).
THE BRAIN
We have described the amazing growth of the brain from conception to birth. By the time it is born, the infant that began as a single cell is estimated to have a brain that contains approximately 100 billion nerve cells, or neurons. Extensive brain development continues after birth, through infancy and later (Sullivan & Wilson, 2018; Vasa & others, 2018). Because the brain is still developing so rapidly in infancy, the infant’s head should be protected from falls or other injuries and the baby should never be shaken. Shaken baby syndrome, which includes brain swelling and hemorrhaging, affects hundreds of babies in the United States each year (Hellgren & others, 2017). One analysis found that fathers were the most frequent perpetrators of shaken baby syndrome, followed by child care providers and boyfriends of the victim’s mother (National Center on Shaken Baby Syndrome, 2012).
Researchers have been successful in using the electroencephalogram (EEG), a measure of the brain’s electrical activity, to learn about the brain’s development in infancy (Bell & others, 2018; Hari & Puce, 2017) (see Figure 2). For example, a recent study found that higher-quality mother-infant interaction early in infancy predicted higher-quality frontal lobe functioning that was assessed with EEG later in infancy (Bernier, Calkins, & Bell, 2016).
FIGURE 2 MEASURING THE ACTIVITY OF AN INFANT’S BRAIN WITH AN ELECTROENCEPHALOGRAM (EEG). By attaching up to 128 electrodes to a baby’s scalp to measure the brain’s activity, researchers have found that newborns produce distinctive brain waves that reveal they can distinguish their mother’s voice from another woman’s, even while they are asleep. Why is it so difficult to measure infants’ brain activity?Courtesy of Vanessa Vogel Farley
Researchers also are increasingly using functional near-infrared spectroscopy (fNIRS), which uses very low levels of near-infrared light to monitor changes in blood oxygen, to study infants’ brain activity (de Oliveira & others, 2018; Emberson & others, 2017a, b; Taga, Watanabe, & Homae, 2018) (see Figure 3). Unlike fMRI, which uses magnetic fields or electrical activity, fNIRS is portable and allows the infants to be assessed as they explore the world around them. And recently Patricia Kuhl and her colleagues (Ferjan Ramirez & others, 2017) at the Institute for Learning and Brain Sciences at the University of Washington have been using magnetoencephalography,Page 108 or MEG, brain-imaging machines to assess infants’ brain activity. MEG maps brain activity by recording magnetic fields produced by electrical currents and is being used to assess such perceptual and cognitive activities as vision, hearing, and language in infants (see Figure 4).
FIGURE 3 FUNCTIONAL NEAR-INFRARED SPECTROSCOPY (fNRIS) Functional near-infrared spectroscopy is increasingly being used to examine the brain activity of infants. fNRIS is non-invasive and can assess infants as they move and explore their environment.©Oli Scarff/Getty ImagesFIGURE 4 MEASURING THE ACTIVITY OF AN INFANT’S BRAIN WITH MAGNETOENCEPHALOGRAPHY (MEG). This baby’s brain activity is being assessed with a MEG brain-imaging device while the baby is listening to spoken words in a study at the Institute of Learning and Brain Sciences at the University of Washington. The infant sits under the machine and when he or she experiences a word, touch, sight, or emotion, the neurons working together in the infant’s brain generate magnetic fields and MEG pinpoints the location of the fields in the brain.©Dr. Patricia Kuhl, Institute for Learning and Brain Sciences, University of Washington
Among the researchers who are making strides in finding out more about the brain’s development in infancy are:
- Charles Nelson and his colleagues (Berens & Nelson, 2015; Bick & Nelson, 2018; Bick & others, 2017; Finch & others, 2017; McLaughlin, Sheridan, & Nelson, 2017; Nelson, 2007, 2012, 2013a, b; Nelson, Fox, & Zeanah, 2014; Vanderwert & others, 2016; Varcin & others, 2016) who are exploring various aspects of memory development, face recognition and facial emotion, and the role of experience in influencing the course of brain development;
- Martha Ann Bell and her colleagues (Bell, 2015; Bell & Cuevas, 2012, 2014, 2015; Bell & others, 2018; Bell, Ross, & Patton, 2018; Broomell & Bell, 2018; Li & others, 2017; MacNeill & others, 2018; Lusby & others, 2016) who are studying brain-behavior links, emotion regulation, inhibitory control, and the integration of cognition and emotion;
- Mark Johnson and his colleagues (Anzures & others, 2016; Gliga & others, 2017; Hakuno & others, 2018; Johnson, Jones, & Gliga, 2015; Johnson, Senju, & Tomalski, 2015; Milosavlijevic & others, 2017; Saez de Urabain & others, 2017; Senju & others, 2016), who are examining neuroconstructivist links between the brain, cognitive and perceptual processes, and environmental influences as well as studying the development of the prefrontal cortex and its functions, early identification of autism, face processing, and early social experiences; and
- John Richards and his colleagues (Emberson & others, 2071a; Lloyd-Fox & others, 2015; Richards, 2009, 2010, 2013; Richards & others, 2015; Richards, Reynolds, & Courage, 2010; Richards & Xie, 2015; Xie, Mallin, & Richards, 2018; Xie & Richards, 2016, 2017) who are examining sustained attention, perception of TV programs, and eye movements.
developmental connection
Brain Development
How does the brain change from conception to birth? Connect to “Prenatal Development and Birth.”
The Brain’s Development At birth, the newborn’s brain is about 25 percent of its adult weight. By the second birthday, the brain is about 75 percent of its adult weight. However, the brain’s areas do not mature uniformly.
Mapping the Brain Scientists analyze and categorize areas of the brain in numerous ways (Bell & others, 2018; Dean & others, 2018; Ferjan Ramirez & others, 2017). The portion farthest from the spinal cord is known as the forebrain. This region includes the cerebral cortex and several structures beneath it. The cerebral cortex covers the forebrain like a wrinkled cap. The brain has two halves, or hemispheres (see Figure 5). Based on ridges and valleys in the cortex, scientists distinguish four main areas, called lobes, in each hemisphere. Although the lobes usually work together, each has a somewhat different primary function (see Figure 6):
FIGURE 5 THE HUMAN BRAIN’S HEMISPHERES. The two hemispheres of the human brain are clearly seen in this photograph. It is a myth that the left hemisphere is the exclusive location of language and logical thinking and that the right hemisphere is the exclusive location of emotion and creative thinking.©A.Glauberman/Science SourceFIGURE 6 THE BRAIN’S FOUR LOBES. Shown here are the locations of the brain’s four lobes: frontal, occipital, temporal, and parietal.
- Frontal lobes are involved in voluntary movement, thinking, personality, and intentionality or purpose.
- Occipital lobes function in vision.
- Temporal lobes have an active role in hearing, language processing, and memory.
- Parietal lobes play important roles in registering spatial location, attention, and motor control.
To some extent, the type of information handled by neuronsPage 109 depends on whether they are in the left or right hemisphere of the cortex (Benjamin & others, 2017; Sidtis & others, 2018). Speech and grammar, for example, depend on activity in the left hemisphere in most people; humor and the use of metaphors depend on activity in the right hemisphere (Holler-Wallscheid & others, 2017). This specialization of function in one hemisphere of the cerebral cortex or the other is called lateralization. However, most neuroscientists agree that complex functions such as reading or performing music involve both hemispheres. Labeling people as “left-brained” because they are logical thinkers or “right-brained” because they are creative thinkers does not correspond to the way the brain’s hemispheres work. Complex thinking in normal people is the outcome of communication between both hemispheres of the brain (Nora & others, 2017; Raemaekers & others, 2018).
At birth, the hemispheres of the cerebral cortex already have started to specialize: Newborns show greater electrical brain activity in the left hemisphere than the right hemisphere when they are listening to speech sounds (Telkemeyer & others, 2011). How are the areas of the brain different in the newborn and the infant from those in an adult, and why do the differences matter? Important differences have been documented at both the cellular and the structural levels.
Changes in Neurons Within the brain, the type of nerve cells called neurons send electrical and chemical signals, communicating with each other. A neuron is a nerve cell that handles information processing (see Figure 7). Extending from the neuron’s cell body are two types of fibers known as axons and dendrites. Generally, the axon carries signals away from the cell body and dendrites carry signals toward it. A myelin sheath, which is a layer of fat cells, encases many axons (see Figure 7). The myelin sheath insulates axons and helps electrical signals travel faster down the axon (Cercignani & others, 2017; van Tilborg & others, 2018). Myelination also is involved in providing energy to neurons and in communication (Saab & Nave, 2017). At the end of the axon are terminal buttons, which release chemicals called neurotransmitters into synapses, which are tiny gaps between neurons’ fibers. Chemical interactions in synapses connect axons and dendrites, allowing information to pass from neuron to neuron (Ismail, Fatemi, & Johnson, 2017; Zhou & others, 2018). Think of the synapse as a river that blocks a road. A grocery truck arrives at one bank of the river, crosses by ferry, and continues its journey to market. Similarly, a message in the brain is “ferried” across the synapse by a neurotransmitter, which pours out information contained in chemicals when it reaches the other side of the river.
FIGURE 7 THE NEURON. (a) The dendrites of the cell body receive information from other neurons, muscles, or glands through the axon. (b) Axons transmit information away from the cell body. (c) A myelin sheath covers most axons and speeds information transmission. (d) As the axon ends, it branches out into terminal buttons.
Neurons change in two very significant ways during the first years of life. First, myelination, the process of encasing axons with fat cells, begins prenatally and continues after birth, even into adolescence and emerging adulthood (Juraska & Willing, 2017). Second, connectivity among neurons increases, creating new neural pathways (Eggebrecht & others, 2017; Zhou & others, 2018). New dendrites grow, connections among dendrites increase, and synaptic connections between axons and dendrites proliferate. Whereas myelination speeds up neural transmissions, the expansion of dendritic connections facilitates the spreading of neural pathways in infant development.
How complex are these neural connections? In a recent analysis, it was estimated that each of the billions of neurons is connected to as many as 1,000 other neurons, producing neural networks with trillions of connections (de Haan, 2015). As we have discussed previously, most of these billions of neurons essentially have been created, have traveled to their correct locations, and are connected to other neurons by the time of full-term birth. Nonetheless, they undergo further differentiation, and neural connectivity patterns continue to change at least into emerging adulthood (Vasa & others, 2018).
Researchers have discovered an intriguing aspect of synaptic connections: nearly twice as many of these connections are made as will ever be used (Huttenlocher & Dabholkar, 1997). The connections that are used survive and become stronger, while the unused ones are replaced by other pathways or disappear. In the language of neuroscience, these connections will be “pruned” (Gould, 2017). For example, the more babies engage in physical activity or use language, the more those pathways will be strengthened.
developmental connection
Brain Development
Changes in the prefrontal cortex in adolescents and older adults have important implications for their cognitive development. Connect to “Physical and Cognitive Development in Adolescence” and “Physical Development in Late Adulthood.”
The age at which “blooming” and subsequent “pruning” of synapses occurs varies by brain region. For example, the peak of synaptic overproduction in the visual cortex occurs at about the fourth postnatal month, followed by a gradual retraction until the middle to end of the preschool years. In areas of the brain involved in hearing and language, a similar, though somewhat later, course is detected. However, in the prefrontal cortex, the area of the brain where higher-level thinking and self-regulation occur, the peak of overproduction takes place at about 1 year of age; it is not until emerging adulthood that adult density of synapses is attained. Both heredity and environment are thought to influence the timing and course of synaptic overproduction and subsequent retraction.
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Early Experience and the Brain Children who grow up in a deprived environment may have depressed brain activity (Bick & Nelson, 2018; Bick & others, 2017; McLaughlin, Sheridan, & Nelson, 2017; Nelson, Fox, & Zeanah, 2014). As shown in Figure 8, a child who grew up in the unresponsive and unstimulating environment of a Romanian orphanage showed considerably depressed brain activity compared with a child who grew up in a normal environment.
FIGURE 8 EARLY DEPRIVATION AND BRAIN ACTIVITY. These two photographs are PET (positron emission tomography) scans, which use radioactive tracers to image and analyze blood flow and metabolic activity in the body’s organs. These scans show the brains of (a) a typically developing child and
(b) an institutionalized Romanian orphan who experienced substantial deprivation since birth. In PET scans, the highest to lowest brain activity is reflected in the colors of red, yellow, green, blue, and black, respectively. As can be seen, red and yellow show up to a much greater degree in the PET scan of the typically developing child than the deprived Romanian orphan.Courtesy of Dr. Harry T. Chugani, Children’s Hospital of Michigan
Are the effects of deprived environments reversible? There is reason to think that for some individuals the answer is “yes” (Dennis & others, 2014). The brain demonstrates both flexibility and resilience. Consider 14-year-old Michael Rehbein. At age 7, he began to experience uncontrollable seizures—as many as 400 a day. Doctors said the only solution was to remove the left hemisphere of his brain where the seizures were occurring. Recovery was slow, but his right hemisphere began to reorganize and take over functions that normally occur in the brain’s left hemisphere, including speech (see Figure 9).
FIGURE 9 PLASTICITY IN THE BRAIN’S HEMISPHERES. (a) Michael Rehbein at 14 years of age. (b) Michael’s right hemisphere (right) has reorganized to take over the language functions normally carried out by corresponding areas in the left hemisphere of an intact brain (left). However, the right hemisphere is not as efficient as the left, and more areas of the brain are recruited to process speech.Courtesy of The Rehbein Family
Neuroscientists believe that what wires the brain—or rewires it, in the case of Michael Rehbein—is repeated experience. Each time a baby tries to touch an attractive object or gazes intently at a face, tiny bursts of electricity shoot through the brain, knitting together neurons into circuits. The results are some of the behavioral milestones we discuss in this chapter.
The Neuroconstructivist View Not long ago, scientists thought that our genes determined how our brains were “wired” and that the cells in the brain responsible for processing information just maturationally unfolded with little or no input from environmental experiences. Whatever brain your heredity had dealt you, you were essentially stuck with. This view, however, turned out to be wrong. Research reveals that the brain has plasticity and its development depends on context (Bick & Nelson, 2018; D’Souza & Karmiloff-Smith, 2018; McLaughlin & Broihier, 2018; Snyder & Smith, 2018).
The infant’s brain depends on experiences to determine how connections are made. Before birth, it appears that genes mainly direct basic wiring patterns. Neurons grow and travel to distant places awaiting further instructions. After birth, the inflowing stream of sights, sounds, smells, touches, language, and eye contact help shape the brain’s neural connections.
In the increasingly popular neuroconstructivist view, (a) biological processes (genes, for example) and environmental conditions (enriched or impoverished, for example) influence the brain’s development; (b) the brain has plasticity and is context dependent; and (c) the child’s cognitive development is closely linked to development of the brain. These factors constrain or advance the construction of cognitive skills (Goldberg, 2017; Mucke & others, 2018; Schreuders & others, 2018; Westermann, Thomas, & Karmiloff-Smith, 2011). The neuroconstructivist view emphasizes the importance of considering interactions between experience and gene expression in the brain’s development, much as the epigenetic view proposes (Moore, 2017; Smith & others, 2018; Westermann, 2016).
developmental connection
Nature and Nurture
In the epigenetic view, development is an ongoing, bidirectional interchange between heredity and the environment. Connect to “Biological Beginnings.”
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SLEEP
Sleep restores, replenishes, and rebuilds our brains and bodies. What function does sleep have in people’s lives? How do sleep patterns change in infancy?
Why Do We Sleep? A number of theories have been proposed about why we sleep. From an evolutionary perspective, all animals sleep and this sleep likely is necessary for survival. Thus, sleep may have developed because animals needed to protect themselves at night. A second perspective is that sleep replenishes and rebuilds the brain and body, which the day’s waking activities can wear out. In support of this restorative function, many of the body’s cells show increased production and reduced breakdowns of proteins during sleep (Frank, 2017). Further, a current emphasis is that sleep is essential to clearing out waste in neural tissues, such as metabolites and cerebrospinal fluid (Aguirre, 2016). A third perspective is that sleep is critical for brain plasticity (Sterpenich, Ceravolo, & Schwartz, 2017). For example, neuroscientists recently have argued that sleep increases synaptic connections between neurons (Areal, Warby, & Mongrain, 2017). These increased synaptic connections during sleep have been linked to improved consolidation of memories (Gui & others, 2017). Further, a research review concluded that not only can sleep improve memory, but losing a few hours of sleep a night is related to negative effects on attention, reasoning, and decision making (Diekelmann, 2014).
In sum, sleep likely serves a number of functions with no one theory accounting for all of the functions. Let’s now turn our attention to sleep in infancy. In later chapters, we will explore sleep through the remainder of the life span.
Sleep that knits up the ravelled sleave of care . . . Balm of hurt minds, nature’s second course. Chief nourisher in life’s feast.
—William Shakespeare
English Playwright, 17th Century
Infant Sleep When we were infants, sleep consumed more of our time than it does now (Goh & others, 2017). The typical newborn sleeps approximately 18 hours a day, but newborns vary greatly in how much they sleep (Dias & others, 2018; Sadeh, 2008). The range is from about 10 hours to about 21 hours a day.
In a recent study, sleep sessions lasted approximately 3.5 hours during the first few months and increased to about 10.5 hours from 3 to 7 months (Mindell & others, 2016). A previous research review concluded that infants 0 to 2 years of age slept an average of 12.8 hours out of the 24, within a range of 9.7 to 15.9 hours (Galland & others, 2012). Another study revealed that by 6 months of age the majority of infants slept through the night, awakening their parents only once or twice a week (Weinraub & others, 2012).
Sleep problems have been estimated to affect 15 to 25 percent of infants. The most common infant sleep-related problem reported by parents is nighttime waking (Dias & others, 2018; Hospital for Sick ChildrenPage 112 & others, 2010). Surveys indicate that 20 to 30 percent of infants have difficulty going to sleep at night and staying asleep until morning (Sadeh, 2008). One study found that nighttime wakings at 1 year of age predicted lower sleep efficiency at 4 years of age (Tikotzky & Shaashua, 2012). Further research found that (1) maternal depression during pregnancy, (2) early introduction of solid foods, (3) infant TV viewing, and (4) child care attendance were related to shorter duration of infant sleep (Nevarez & others, 2010). And a recent study revealed that later bedtime and less sleep across a 24-hour period were linked to infants having more separation distress, greater inhibition, and higher anxiety and depression levels (Mindell & others, 2017).
Research also indicates that parental factors other than maternal depression are linked to infants’ sleep patterns (Field, 2017; Volkovich & others, 2018; Yu & others, 2017). A recent study found that maternal sleep when the infant was 3 months of age predicted the infant’s sleep patterns at 6 months of age and that increased involvement of the father in caregiving responsibilities improved the infant’s sleep (Tikotzky & others, 2015). And other recent research indicated that a higher level of maternal emotional availability at bedtime was associated with a lower level of infant distress at bedtime and longer infant sleep duration (Philbrook & Teti, 2016).
Cultural variations influence infant sleeping patterns (Field, 2017). For example, in the Kipsigis culture in Kenya, infants sleep with their mothers at night and are permitted to nurse on demand (Super & Harkness, 1997). During the day, they are strapped to their mothers’ backs, accompanying them on daily rounds of chores and social activities. As a result, the Kipsigis infants do not sleep through the night until much later than American infants do. During the first eight months of postnatal life, Kipsigis infants rarely sleep longer than three hours at a stretch, even at night. This sleep pattern contrasts with that of American infants, many of whom begin to sleep up to eight hours a night by 8 months of age.
REM Sleep In REM sleep, the eyes flutter beneath closed lids; in non-REM sleep, this type of eye movement does not occur and sleep is more quiet (Bathory & Tomopoulos, 2017). Figure 10 shows developmental changes in the average number of total hours spent in REM and non-REM sleep. By the time they reach adulthood, individuals spend about one-fifth of their night in REM sleep, and REM sleep usually appears about one hour after non-REM sleep. However, about half of an infant’s sleep is REM sleep, and infants often begin their sleep cycle with REM sleep rather than non-REM sleep. A much greater amount of time is taken up by REM sleep in infancy than at any other point in the life span. By the time infants reach 3 months of age, the percentage of time they spend in REM sleep falls to about 40 percent, and REM sleep no longer begins their sleep cycle.
FIGURE 10 DEVELOPMENTAL CHANGES IN REM AND NON-REM SLEEP
Why do infants spend so much time in REM sleep? Researchers are not certain. The large amount of REM sleep may provide infants with added self-stimulation, since they spend less time awake than do older children. REM sleep also might promote the brain’s development in infancy (Graven, 2006).
When adults are awakened during REM sleep, they frequently report that they have been dreaming, but when they are awakened during non-REM sleep, they are much less likely to report having been dreaming (Cartwright & others, 2006). Since infants spend more time than adults in REM sleep, can we conclude that they dream a lot? We don’t know whether infants dream or not, because they don’t have any way of reporting dreams.
Shared Sleeping Sleeping arrangements for newborns vary from culture to culture (Field, 2017). For example, sharing a bed with a mother is a common practice in many cultures, such as Guatemala and China, whereas in others, such as the United States and Great Britain, newborns usually sleep in a crib, either in the same room as the parents or in a separate room. In some cultures, infants sleep with the mother until they are weaned, after which they sleep with siblings until middle and late childhood (Walker, 2006). Whatever the sleeping arrangements, it is recommended that the infant’s bedding provide firm support and that the crib has side rails (Kreth & others, 2018).
In the United States, shared sleeping remains a controversial issue (Burnham, 2014). Some experts recommend it and others argue against it, although recently the recommendation trend has been to avoid infant-parent bed sharing, especially if the infant is younger than 6 months of age (Byard, 2012a, b; Field, 2017; Mitchell & others, 2017; Weber & others, 2012). In a recent study, infant-parent bed sharing was associated with more night waking for mothers as wellPage 113 as infants, and more marital distress (Teti & others, 2016). The American Academy of Pediatrics Task Force on Infant Positioning and SIDS (AAPTFIPS) (2000) recommends against shared sleeping. Its members argue that in some instances bed sharing might lead to sudden infant death syndrome (SIDS), as could be the case if a sleeping mother rolls over on her baby (Moon & others, 2017). Recent studies have found that bed sharing is linked with a higher incidence of SIDS, especially when parents smoke (Adams, Ward, & Garcia, 2015). Further, a recent large-scale study in six countries (including the United States) found that parents of 6- to 12-month-old infants reported earlier bedtimes, shorter time to fall asleep, fewer sleep interruptions, and more total sleep when the infants slept in a separate room compared with infants sleeping in the same room or same bed with their parents (Mindell, Leichman, & Walters, 2018).
SIDS Sudden infant death syndrome (SIDS) is a condition that occurs when infants stop breathing, usually during the night, and die suddenly without any apparent reason. SIDS continues to be a leading cause of infant death in the United States, with more than 2,000 infant deaths annually attributed to SIDS (NICHD, 2018). Risk of SIDS is highest at 2 to 4 months of age.
developmental connection
Sleep
What are some sleep problems that children encounter in early childhood? Connect to “Physical and Cognitive Development in Early Childhood.”
Since 1992, the American Academy of Pediatrics (AAP) has recommended that infants be placed to sleep on their backs (supine position) to reduce the risk of SIDS, and the frequency of prone sleeping (on the stomach) among U.S. infants has dropped dramatically (AAPTFIPS, 2000). Researchers have found that SIDS does indeed decrease when infants sleep on their backs rather than their stomachs or sides (Bombard & others, 2018; Siren, 2017; Sperhake, Jorch, & Bajanowski, 2018). Why? Because sleeping on their backs increases their access to fresh air and reduces their chances of getting overheated.
developmental connection
Sleep
Sleep patterns change in adolescence and are linked to changes in the brain. Connect to “Physical and Cognitive Development in Adolescence.”
In addition to sleeping in a prone position, researchers have found that the following factors are linked to SIDS:
- SIDS occurs more often in infants with abnormal brain stem functioning involving the neurotransmitter serotonin (Rognum & others, 2014; Rubens & Sarnat, 2013).
- Heart arrhythmias are estimated to occur in as many as 15 percent of SIDS cases, and two studies found that gene mutations were linked to the occurrence of these arrhythmias (Brion & others, 2012; Van Norstrand & others, 2012).
- Six percent of infants with sleep apnea, a temporary cessation of breathing in which the airway is completely blocked, usually for 10 seconds or longer, die of SIDS (Ednick & others, 2010).
- Breast feeding is linked to a lower incidence of SIDS (Carlin & Moon, 2017).
- Low birth weight infants are 5 to 10 times more likely to die of SIDS than are their normal-weight counterparts (Horne & others, 2002).
- SIDS is more likely to occur in infants who do not use a pacifier when they go to sleep than in those who do use a pacifier (Carlin & Moon, 2017). A recent research review confirmed that pacifier use is linked to a lower incidence of SIDS (Alm & others, 2016).
- Infants whose siblings have died of SIDS are two to four times as likely to die of it (Lenoir, Mallet, & Calenda, 2000).
- African American and Eskimo infants are four to six times as likely as all others to die of SIDS (Kitsantas & Gaffney, 2010; Moon & others, 2017).
- SIDS is more common in lower socioeconomic groups (Hogan, 2014).
- SIDS is more common in infants who are passively exposed to cigarette smoke (Horne, 2018; Salm Ward & Balfour, 2016).
- SIDS is more common when infants and parents share the same bed (Carlin & Moon, 2017; Moon & others, 2017). A recent Swedish study confirmed that bed sharing was more common in SIDS cases than in other types of infant deaths (Mollborg & others, 2015).
- SIDS is more common if infants sleep in soft bedding (McGarvey & others, 2006).
- SIDS is less common when infants sleep in a bedroom with a fan. One study revealed that sleeping in a bedroom with a fan lowers the risk of SIDS by 70 percent (Coleman-Phox, Odouli, & Li, 2008).
Is this a good sleep position for infants? Why or why not?©Maria Teijeiro/Getty Images
It is generally accepted that the most critical factor in predicting whether an infant will develop SIDS is prone sleeping. As public awareness has grown regarding the importance of not letting infants sleep in a prone position, the number of infant deaths in the United States has decreased, although SIDS still is one of the leading causes of infant deathPage 114 (Bombard & others, 2018). In a recent research review, it was concluded that the two other factors that place infants at the highest risk for SIDS are (1) maternal smoking and (2) bed sharing (Mitchell & Krous, 2015).
One concern raised by critics of the “back to sleep movement” (ensuring that young infants sleep on their back rather than their stomach) is a decline in prone skills. To prevent this decline, many mothers provide their young infants with “tummy time” by periodically placing them on their stomachs when they are awake.
Sleep and Cognitive Development Might infant sleep be linked to children’s cognitive development? A recent research review indicated that there is a positive link between infant sleep and cognitive functioning, including memory, language, and executive function (Tham, Schneider, & Broekman, 2017). A study also revealed that a lower quality of sleep at 1 year of age was linked to lower attention regulation and more behavior problems at 3 to 4 years of age (Sadeh & others, 2015). And in another study, infants with poorer sleep patterns showed more distractibility during an attention task (Geva, Yaron, & Kuint, 2016). The link between infant sleep and children’s cognitive functioning likely occurs because of sleep’s role in brain maturation and memory consolidation, which may improve daytime alertness and learning.
NUTRITION
From birth to 1 year of age, human infants nearly triple their weight and increase their length by 50 percent. What do they need to sustain this growth?
Nutritional Needs and Eating Behavior Individual differences among infants in terms of their nutrient reserves, body composition, growth rates, and activity patterns make defining actual nutrient needs difficult (Borowitz & Borowitz, 2018; Rolfes & Pinna, 2018). However, because parents need guidelines, nutritionists recommend that infants consume approximately 50 calories per day for each pound they weigh—more than twice an adult’s caloric requirement per pound.
A number of developmental changes involving eating characterize the infant’s first year (Leow & others, 2017). As infants’ motor skills improve, they change from using suck-and-swallow movements with breast milk or formula to chew-and-swallow movements with semisolid and then more complex foods. As their fine motor control improves in the first year, they transition from being fed by others toward self-feeding. “By the end of the first year of life, children can sit independently, can chew and swallow a range of textures, are learning to feed themselves, and are making the transition to the family diet and meal patterns” (Black & Hurley, 2007, p. 1). At this point, infants need to have a diet that includes a variety of foods—especially fruits and vegetables.
Caregivers play very important roles in infants’ early development of eating patterns (Baye, Tariku, & Mouquet-Rivier, 2018; Brown, 2017). Caregivers who are not sensitive to developmental changes in infants’ nutritional needs, caregivers who are negligent, and conditions of poverty can contribute to the development of eating problems in infants (Black & Hurley, 2017; Perez-Escamilla & Moran, 2017). One study found that low maternal sensitivity when infants were 15 and 24 months of age was linked to a higher risk of obesity in adolescence (Anderson & others, 2012). And in a recent study, infants who were introduced to vegetables at 4 to 5 months of age showed less fussy eating behavior at 4 years of age than their counterparts who were introduced to vegetables after 6 months (de Barse & others, 2017).
A national study of more than 3,000 randomly selected 4- to 24-month-olds documented that many U.S. parents were feeding their babies too much junk food and not giving them enough fruits and vegetables (Fox & others, 2004). Up to one-third of the babies ate no vegetables and fruit but frequently ate French fries, and almost half of the 7- to 8-month-old babies were fed desserts, sweets, or sweetened drinks. By 15 months, French fries were the most common vegetable the babies ate.
Such poor dietary patterns early in development can result in more infants being overweight (Black & Hurley, 2017; Blake, 2017; Feldman-Winter & others, 2018). In addition to consuming too many French fries, sweetened drinks, and desserts, are there other factors that might explain increased numbers of overweight U.S. infants? A mother’s weight gain during pregnancy and a mother’s own high weight before pregnancy may be factors (Catalano & Shankar, 2017). Also, an important factor likely is whether an infant is breast fed or bottle fed (Uwaezuoke, Eneh, & Ndu, 2017). Breast-fed infants have lower rates of weight gain than bottle-fed infants in childhood and adolescence, and it is estimated that breast feeding reduces the risk of obesity by approximatelyPage 115 20 percent (Uwaezuoke, Eneh, & Ndu, 2017).
Breast versus Bottle Feeding For the first four to six months of life, human milk or an alternative formula is the baby’s source of nutrients and energy. For years, debate has focused on whether breast feeding is better for the infant than bottle feeding. The growing consensus is that breast feeding is better for the baby’s health (Blake, Munoz, & Volpe, 2019; DeBruyne & Pinna, 2017; Thompson & Manore, 2018). Since the 1970s, breast feeding by U.S. mothers has soared (see Figure 11). In 2016, 81 percent of U.S. mothers breast fed their newborns, and 52 percent breast fed their 6-month-olds (Centers for Disease Control and Prevention, 2016). The American Academy of Pediatrics Section on Breastfeeding (2012) reconfirmed its recommendation of exclusive breast feeding in the first six months followed by continued breast feeding as complementary foods are introduced, and further breast feeding for one year or longer as mutually desired by the mother and infant.
FIGURE 11 TRENDS IN BREAST FEEDING IN THE UNITED STATES: 1970–2016
What are some of the benefits of breast feeding? The following conclusions have been supported by research.
Outcomes for the Child
- Gastrointestinal infections. Breast-fed infants have fewer gastrointestinal infections (Bartick & others, 2017, 2018).
- Respiratory tract infections. Breast-fed infants have fewer infections of the lower respiratory tract (Bartick & others, 2018).
- Allergies. A recent research review found no support for breast feeding reducing the risk of allergies in young children (Heinrich, 2017).
- Asthma. Exclusive breast feeding for three months protects against wheezing in babies, but whether it prevents asthma in older children is unclear (Wang & others, 2018). However, a recent Japanese study found that breast feeding was linked to a lower incidence of asthma from 6 to 42 months of age (Yamakawa & others, 2015).
- Ear, throat, and sinus infections. One study found that infants who had been breast fed for 9 months or longer were less likely to have developed ear, throat, and sinus infections in the past year when they were 6 years old than their counterparts who had been breast fed for 3 months or less (Li & others, 2014). Breast-fed infants also are less likely to develop otitis media, a middle ear infection (Pelton & Leibovitz, 2009).
- Overweight and obesity. Consistent evidence indicates that breast-fed infants are less likely to become overweight or obese in childhood, adolescence, and adulthood (Catalano & Shankar, 2017; Uwaezuoke, Eneh, & Ndu, 2018).
- Diabetes. Breast-fed infants are less likely to develop type 1 diabetes in childhood (Lund-Blix & others, 2015) and type 2 diabetes in adulthood (Minniti & others, 2014).
- SIDS. Breast-fed infants have lower rates of SIDS (Bartick & others, 2017b; Wennergren & others, 2015).
- Hospitalization. A recent study of more than 500,000 Scottish children found that those who were breast fed exclusively at 6 to 8 weeks of age were less likely to have ever been hospitalized through early childhood than their formula-fed counterparts (Ajetunmobi & others, 2015). Other recent research has found that breast-fed infants had lower rates of hospitalization for a number of conditions, including gastrointestinal problems and lower respiratory tract infection, and breast-feeding mothers had lower rates of hospitalization for cardiovascular problems and diabetes (Bartick & others, 2018).
Human milk or an alternative formula is a baby’s source of nutrients for the first four to six months. The growing consensus is that breast feeding is better for the baby’s health, although controversy still swirls about the benefits of breast feeding in comparison with bottle feeding. Why is breast feeding strongly recommended by pediatricians?©JGI/Getty Images
In large-scale research reviews, no conclusivePage 116 evidence for the benefits of breast feeding was found for children’s cognitive development and cardiovascular health (Agency for Healthcare Research and Quality, 2007; Ip & others, 2009).
Outcomes for the Mother
- Breast cancer. Consistent evidence indicates a lower incidence of breast cancer in women who breast feed their infants (Bartick & others, 2017b; Mayor, 2015).
- Ovarian cancer. Evidence also reveals a reduction in ovarian cancer in women who breast feed their infants (Stuebe & Schwartz, 2010).
- Type 2 diabetes. Some evidence suggests that there is a reduction in type 2 diabetes in women who breast feed their infants (Bartick & others, 2017b).
In large-scale research reviews, no conclusive evidence could be found for maternal benefits of breast feeding involving return to prepregnancy weight, reduced rates of osteoporosis, and decreased risk of postpartum depression (Agency for Healthcare Research and Quality, 2007; Ip & others, 2009). However, one study revealed that women who breast fed their infants had a lower incidence of metabolic syndrome (a disorder characterized by obesity, hypertension, and insulin resistance) in midlife (Ram & others, 2008).
Many health professionals have argued that breast feeding facilitates the development of an attachment bond between the mother and infant (Britton, Britton, & Gronwaldt, 2006; Wittig & Spatz, 2008). However, a research review found that the positive role of breast feeding on the mother-infant relationship is not supported by research (Jansen, de Weerth, & Riksen-Walraven, 2008). The review concluded that recommending breast feeding should not be based on its role in improving the mother-infant relationship but rather on its positive effects on infant and maternal health. Also, researchers have not consistently found links between breast feeding and higher intelligence in children, although in two recent studies, breast feeding was associated with a small increase in children’s intelligence (Bernard & others, 2017; Kanazawa, 2015).
Which women are least likely to breast feed? They include mothers who work full-time outside the home, mothers under age 25, mothers without a high school diploma, African American mothers, and mothers in low-income circumstances (Merewood & others, 2007). In one study of low-income mothers in Georgia, interventions (such as counseling focused on the benefits of breast feeding and the free loan of a breast pump) increased the incidence of breast feeding (Ahluwalia & others, 2000). Increasingly, mothers who return to work during the infant’s first year of life use a breast pump to extract breast milk that can be stored for later feeding of the infant when the mother is not present.
As mentioned earlier, the American Academy of Pediatrics Section on Breastfeeding (2012) strongly endorses exclusive breast feeding for the first 6 months and further recommends breast feeding for another year. Are there circumstances when mothers should not breast feed? Yes, a mother should not breast feed (1) when she is infected with HIV or some other infectious disease that can be transmitted through her milk, (2) if she has active tuberculosis, or (3) if she is taking any drug that may not be safe for the infant (Brown & others, 2017; Schultz, Kostic, & Kharasch, 2018; Williams & others, 2016).
Some women cannot breast feed their infants because of physical difficulties; others feel guilty if they terminate breast feeding early. Mothers may also worry that they are depriving their infants of important emotional and psychological benefits if they bottle feed rather than breast feed. Some researchers have found, however, that there are no psychological differences between breast-fed and bottle-fed infants (Ferguson, Harwood, & Shannon, 1987; Young, 1990).
A further issue in interpreting the benefits of breast feeding was underscored in large-scale research reviews (Agency for Healthcare Research and Quality, 2007; Ip & others, 2009). While highlighting a number of breast feeding benefits for children and mothers, the report issued a caution about breast feeding research: None of the findings imply causality. Breast versus bottle feeding studies are correlational rather than experimental, and women who breast feed are wealthier, older, more educated, and likely more health-conscious than their bottle feeding counterparts, which could explain why breast-fed children are healthier.
developmental connection
Research Methods
How does a correlational study differ from an experimental study? Connect to “Introduction.”
Malnutrition in Infancy Many infants around the world are malnourished (UNICEF, 2018). Early weaning of infants from breast milk to inadequate sources of nutrients, such as unsuitable and unsanitary cow’s milk formula, can cause protein deficiency and malnutrition in infants. However, as we saw in the discussion following the chapter opening story, a concern in developing countries is the increasing number of women who are HIV-positive and the fear that they will transmit this virus to their offspring (Croffut & others, 2018). Breast feeding is more optimal for mothers and infants in developing countries, except for mothers who have or are suspected of having HIV/AIDS.
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connecting development to life
Improving the Nutrition of Infants and Young Children Living in Low-Income Families
Poor nutrition is a special concern in the lives of infants from low-income families. To address this problem in the United States, the WIC (Women, Infants, and Children) program provides federal grants to states for healthy supplemental foods, health care referrals, and nutrition education for women from low-income families beginning in pregnancy, and to infants and young children up to 5 years of age who are at nutritional risk (Chang, Brown, & Nitzke, 2017; Gilmore & others, 2017). WIC serves approximately 7,500,000 participants in the United States.
Positive influences on infants’ and young children’s nutrition and health have been found for participants in WIC (Chen & others, 2018; Gross & others, 2017; Lee & others, 2017; Martinez-Brockman & others, 2018; McCoy & others, 2018). One study revealed that a WIC program that introduced peer counseling services for pregnant women increased breast feeding initiation by 27 percent (Olson & others, 2010a, b). Another study found that entry during the first trimester of pregnancy to the WIC program in Rhode Island reduced rates of maternal cigarette smoking (Brodsky, Viner-Brown, & Handler, 2009). Also, a multiple-year literacy intervention with Spanish-speaking families in the WIC program in Los Angeles increased literacy resources and activities at home, which in turn led to a higher level of school readiness in children (Whaley & others, 2011). And in recent longitudinal studies, when mothers participated prenatally and in early childhood in WIC programs their young children showed short-term cognitive benefits and longer-term reading and math benefits (Jackson, 2015).
Participants in the WIC program. What are some changes the WIC program is trying to implement?Source: USDA Food and Nutrition Service, Supplemental Nutrition Assistance Program USDA Food and Nutrition Service “SNAP Photo Gallery/Jen Mitchell SNAP-Ed Connection http://snap.nal.usda.gov”
Why would the WIC program provide lactation counseling as part of its services?
A large-scale study that examined feeding practices in 28 developing countries found that the practices were far from optimal (Arabi & others, 2012). In this study, only 25 percent of infants 5 months of age and younger were breast fed. Also, feeding guidelines call for introducing complementary foods (solid and semisolid foods) beginning at 6 months. However, in this study, only 50 percent of the caregivers reported feeding their 6- to 8-month-olds complementary foods.
Even if it is not fatal, severe and lengthy malnutrition is detrimental to physical, cognitive, and social development (Donatelle & Ketcham, 2018; UNICEF, 2018; Wardlaw, Smith, & Collene, 2018). One study found that Asian Indian children who had a history of chronic malnutrition performed more poorly on tests of attention and memory than their counterparts who were not malnourished (Kar, Rao, & Chandramouli, 2008). And a longitudinal study revealed that Barbadians who had experienced moderate to severe protein/energy malnutrition during infancy had persisting attention deficits when they were 40 years old (Galler & others, 2012). Researchers also have found that interventions can benefit individuals who have experienced malnutrition in infancy. For example, in one study standard nutritional care combined with a psychosocial intervention (group meetings with mothers and play sessions with infants, as well as six months of home visits) reduced the negative effects of malnutrition on severely malnourished Bangladeshi 6- to 24-month-olds’ cognitive development (Najar & others, 2008).
To read about programs designed to improve infants’ and young children’s nutrition, see Connecting Development to Life.
Adequate early nutrition is an important aspect of healthy development (Rolfes & Pinna, 2018). In addition to sound nutrition, children need a nurturing, supportive environment (Black & Hurley, 2017; Blake, 2017). One individual who has stood out as an advocate of caring for children and who has been especially passionate about preventing child obesity is pediatrician Faize Mustafa-Infante, who is featured in Connecting with Careers.
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connecting with careers
Faize Mustafa-Infante
Dr. Mustafa-Infante grew up in Colombia, South America. Her initial profession was as an elementary school teacher in Colombia and then she obtained her medical degree with a specialty in pediatrics. Once she finished her medical training, she moved to San Bernardino, California, working as a health educator with a focus on preventing and treating child obesity in low-income communities. Dr. Mustafa-Infante currently works at Mission Pediatrics in Riverside, California, where she mainly treats infants. She continues her effort to prevent obesity in children and also serves as a volunteer for Ayacucho Mission, a nonprofit organization that provides culturally sensitive medical care for people living in poverty in Ayacucho, Peru. With regard to her cultural background, Dr. Mustafa-Infante describes herself as a Latino doctor with a middle-eastern name that reflects her strong family commitments to both heritages. Dr. Mustafa says that hard work and education have been the keys to her success and personal satisfaction.
For more information about what pediatricians do, see the Careers in Life-Span Development appendix.
Review Connect Reflect
LG1 Discuss physical growth and development in infancy.
Review
- What are cephalocaudal and proximodistal patterns?
- What changes in height and weight take place in infancy?
- What are some key features of the brain and its development in infancy?
- What changes occur in sleep during infancy?
- What are infants’ nutritional needs?
Connect
- What types of brain research technology can be used to study infants that cannot be used to study them before they are born? Which techniques can be used on adults but not infants? How might these limitations affect our understanding of brain development across the life span?
Reflect Your Own Personal Journey of Life
- What sleep and nutrition guidelines would you follow for enhancing the health and safety of your own infant?
2 Motor Development
LG2 Describe infants’ motor development.
The Dynamic Systems View
Reflexes
Gross Motor Skills
Fine Motor Skills
As a newborn, Ramona, whom you read about in the chapter opening story, could suck, fling her arms, and tightly grip a finger placed in her tiny hand. Within just two years, she would be toddling around on her own, opening doors and jars as she explored her little world. Are her accomplishments inevitable? How do infants develop their motor skills, and which skills do they develop at specific ages?
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THE DYNAMIC SYSTEMS VIEW
Developmentalist Arnold Gesell (1934) thought his painstaking observations had revealed how people develop their motor skills. He had discovered that infants and children develop rolling, sitting, standing, and other motor skills in a fixed order and within specific time frames. These observations, said Gesell, show that motor development comes about through the unfolding of a genetic plan, or maturation.
Later studies, however, demonstrated that the sequence of developmental milestones is not as fixed as Gesell indicated and not due as much to heredity as Gesell argued (Adolph, 2018; Adolph & Robinson, 2015). Beginning in the 1980s, the study of motor development experienced a renaissance as psychologists developed new insights about how motor skills develop (Adolph, 2018; Kretch & Adolph, 2018). One increasingly influential perspective is dynamic systems theory, proposed by Esther Thelen (Thelen & Smith, 1998, 2006).
According to dynamic systems theory, infants assemble motor skills for perceiving and acting. Notice that perception and action are coupled, according to this theory. To develop motor skills, infants must perceive something in their environment that motivates them to act and use their perceptions to fine-tune their movements. Motor skills assist infants in reaching their goals (Adolph, 2018).
Esther Thelen is shown conducting an experiment to discover how infants learn to control their arm movements to reach and grasp for objects. A computer device is used to monitor the infant’s arm movements and to track muscle patterns. Thelen’s research is conducted from a dynamic systems perspective. What is the nature of this perspective?Courtesy of Dr. David Thelen
How is a motor skill developed, according to this theory? When infants are motivated to do something, they might create a new motor behavior. The new behavior is the result of many converging factors: the development of the nervous system, the body’s physical properties and its possibilities for movement, the goal the child is motivated to reach, and availability of environmental support for the skill. For example, babies learn to walk only when maturation of the nervous system allows them to control certain leg muscles, when they want to move, when their legs have grown strong enough to support their weight, and when they have sufficient balance control to support their body on one leg.
Mastering a motor skill requires the infant’s active efforts to coordinate several components of the skill. Infants explore and select possible solutions to the demands of a new task; they assemble adaptive patterns by modifying their current movement patterns (Adolph, 2018). The first step occurs when the infant is motivated by a new challenge—such as the desire to cross a room—and gets into the “ballpark” of the task demands by taking a couple of stumbling steps. Then, the infant “tunes” these movements to make them smoother and more effective. The tuning is achieved through repeated cycles of action and perception of the consequences of that action. According to the dynamic systems view, even universal milestones, such as crawling, reaching, and walking, are learned through this process of adaptation: Infants modulate their movement patterns to fit a new task by exploring and selecting possible configurations (Adolph, 2018; Comalli, Persand, & Adolph, 2017).
To see how dynamic systems theory explains motor behavior, imagine that you offer a new toy to a baby named Gabriel (Thelen & others, 1993). There is no exact program that can tell Gabriel ahead of time how to move his arm and hand and fingers to grasp the toy. Gabriel must adapt to his goal—grasping the toy—and the context. From his sitting position, he must make split-second adjustments to extend his arm, holding his body steady so that his arm and torso don’t plow into the toy. Muscles in his arm and shoulder contract and stretch in a host of combinations, exerting a variety of forces. He improvises a way to reach out with one arm and wrap his fingers around the toy.
Thus, according to dynamic systems theory, motor development is not a passive process in which genes dictate the unfolding of a sequence of skills over time. Rather, the infant actively puts together a skill to achieve a goal within the constraints set by the infant’s body and environment. Nature and nurture, the infant and the environment, are all working together as part of an ever-changing system.
As we examine the course of motor development, we will describe how dynamic systems theory applies to some specific skills. First, though, let’s examine the beginning of motor development: the infant’s reflexes.
How might dynamic systems theory explain the development of learning to walk?©Di Studio/Shutterstock
REFLEXES
The newborn is not completely helpless. Among other things, it has some basic reflexes. For example, when submerged in water, the newborn automatically holds its breath and contracts its throat to keep water out.
Reflexes are built-in reactions to stimuli; they governPage 120 the newborn’s movements, which are automatic and beyond the newborn’s control. Reflexes are genetically carried survival mechanisms. They allow infants to respond adaptively to their environment before they have had the opportunity to learn. The rooting and sucking reflexes are important examples. Both have survival value for newborn mammals, who must find a mother’s breast to obtain nourishment. The rooting reflex occurs when the infant’s cheek is stroked or the side of the mouth is touched. In response, the infant turns its head toward the side that was touched in an apparent effort to find something to suck. The sucking reflex occurs when newborns automatically suck an object placed in their mouth. This reflex enables newborns to get nourishment before they have associated a nipple with food and also serves as a self-soothing or self-regulating mechanism.
Another example is the Moro reflex, which occurs in response to a sudden, intense noise or movement (see Figure 12). When startled, the newborn arches its back, throws back its head, and flings out its arms and legs. Then the newborn rapidly draws in its arms and legs. The Moro reflex is believed to be a way of grabbing for support while falling; it would have had survival value for our primate ancestors.
FIGURE 12 NEWBORN REFLEXES. Young infants have several reflexes, including the Moro reflex (top) and grasping reflex (bottom).(Top) ©Petit Format/Science Source; (bottom) ©Stockbyte/PunchStock
Some reflexes—coughing, sneezing, blinking, shivering, and yawning, for example—persist throughout life. They are as important for the adult as they are for the infant. Other reflexes, though, disappear several months following birth, as the infant’s brain matures and voluntary control over many behaviors develops. The rooting and Moro reflexes, for example, tend to disappear when the infant is 3 to 4 months old.
The movements of some reflexes eventually become incorporated into more complex, voluntary actions. One important example is the grasping reflex, which occurs when something touches the infant’s palms (see Figure 12). The infant responds by grasping tightly. By the end of the third month, the grasping reflex diminishes and the infant shows a more voluntary grasp. As its motor coordination becomes smoother, the infant will grasp objects, carefully manipulate them, and explore their qualities.
The old view of reflexes is that they were exclusively genetic, built-in mechanisms that governed the infant’s movements. The new perspective on infant reflexes is that they are not automatic or completely beyond the infant’s control. For example, infants can alternate the movement of their legs to make a mobile jiggle or change their sucking rate to listen to a recording (Adolph & Robinson, 2015).
GROSS MOTOR SKILLS
Ask any parents about their baby, and sooner or later you are likely to hear about one or more motor milestones, such as “Cassandra just learned to crawl,” “Jesse is finally sitting alone,” or “Angela took her first step last week.” Parents proudly announce such milestones as their children transform themselves from babies unable to lift their heads to toddlers who grab things off the grocery store shelf, chase a cat, and participate actively in the family’s social life (Thelen, 2000). These milestones are examples of gross motor skills, which involve large-muscle activities such as moving one’s arms and walking.
The Development of Posture How do gross motor skills develop? As a foundation, these skills require postural control. For example, to track moving objects, you must be able to control the movement of your head in order to stabilize your gaze; before you can walk, you must be able to balance on one leg.
Posture is more than just holding still and straight. Posture is a dynamic process that is linked with sensory information in the skin, joints, and muscles, which tell us where we are in space; in vestibular organs in the inner ear that regulate balance and equilibrium; and in vision and hearing (Soska, Robinson, & Adolph, 2015).
Newborn infants cannot voluntarily control their posture. Within a few weeks, though, they can hold their heads erect, and soon they can lift their heads while prone. By 2 months of age, babies can sit while supported on a lap or an infant seat, but they cannot sit independently until they are 6 or 7 months of age. Standing also develops gradually during the first year of life. By about 8 to 9 months of age, infants usually learn to pull themselves up and hold on to a chair, and they often can stand alone by about 10 to 12 months of age.
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Learning to Walk Locomotion and postural control are closely linked, especially in walking upright (Kretch & Adolph, 2018). To walk upright, the baby must be able both to balance on one leg as the other is swung forward and to shift weight from one leg to the other.
Even young infants can make the alternating leg movements that are needed for walking. The neural pathways that control leg alternation are in place from a very early age, even at birth or before. Indeed, researchers have found that alternating leg movements occur during the fetal period and at birth (Adolph & Robinson, 2015). Both alternating leg movements and forward stepping movements occur early in development and are precursors to walking.
If infants can produce forward stepping movements so early, why does it take them so long to learn to walk? The key skills in learning to walk appear to be stabilizing balance on one leg long enough to swing the other forward and shifting weight without falling. These are difficult biomechanical problems to solve, and it takes infants about a year to do it.
In learning to locomote, infants learn what kinds of places and surfaces are safe for locomotion (Adolph, 2018; Karasik, Tamis-LeMonda, & Adolph, 2016). Karen Adolph (1997) investigated how experienced and inexperienced crawling infants and walking infants go down steep slopes (see Figure 13). Newly crawling infants, who averaged about 8½ months in age, rather indiscriminately went down the steep slopes, often falling in the process (with their mothers next to the slope to catch them). After weeks of practice, the crawling babies became more adept at judging which slopes were too steep to crawl down and which ones they could navigate safely. New walkers also could not judge the safety of the slopes, but experienced walkers accurately matched their skills with the steepness of the slopes. They rarely fell downhill, either refusing to go down the steep slopes or going down backward in a cautious manner. Experienced walkers perceptually assessed the situation—looking, swaying, touching, and thinking before they moved down the slope. With experience, both the crawlers and the walkers learned to avoid the risky slopes where they would fall, integrating perceptual information with the development of a new motor behavior. In this research, we again see the importance of perceptual-motor coupling in the development of motor skills. Thus, practice is very important in the development of new motor skills (Adolph & Berger, 2015).
FIGURE 13 THE ROLE OF EXPERIENCE IN CRAWLING AND WALKING INFANTS’ JUDGMENTS OF WHETHER TO GO DOWN A SLOPE. Karen Adolph (1997) found that locomotor experience rather than age was the primary predictor of adaptive responding on slopes of varying steepness. Newly crawling and walking infants could not judge the safety of the various slopes. With experience, they learned to avoid slopes where they would fall. When expert crawlers began to walk, they again made mistakes and fell, even though they had judged the same slope accurately when crawling. Adolph referred to this as the specificity of learning because it does not transfer across crawling and walking.Courtesy of Dr. Karen Adolph, New York University
Practice is especially important in learning to walk (Adolph, 2018; Adolph & Robinson, 2015). “Thousands of daily walking steps, each step slightly different from the last because of variations in the terrain and the continually varying biomechanical constraints on the body, may help infants to identify the relevant” combination of strength and balance required to improve their walking skills (Adolph, Vereijken, & Shrout, 2003, p. 495). In one study, Adolph and her colleagues (2012) observed 12- to 19-month-olds during free play. Locomotor experience was extensive, with the infants averaging 2,368 steps and 17 falls per hour.
A recent study explored how infants plan and guide their locomotion in the challenging context of navigating a series of bridges varying in width (Kretch & Adolph, 2018). Infants’ visual exploration (direction of their gaze) was assessed using a head-mounted eye-tracking device, and their locomotor actions were captured using video. The 14-month-olds engaged in visual exploration from a distance as an initial assessmentPage 122 before they crossed almost every bridge. The visual information led to modifications in their gait when approaching narrow bridges, and they used haptic (touch) information at the edge of the bridges. As they gained more walking experience, their exploratory behaviors became more efficient and they became more adept at deciding which bridges were safe to walk across.
Might the development of walking be linked to advances in other aspects of development? Walking allows the infant to gain contact with objects that were previously out of reach and to initiate interaction with parents and other adults, thereby promoting language development (Adolph & Robinson, 2015; He, Walle, & Campos, 2015). Thus, just as with advances in postural skills, walking skills can produce a cascade of changes in the infant’s development (Marrus & others, 2018).
The First Year: Motor Development Milestones and Variations Figure 14 summarizes the range of ages at which infants accomplish various gross motor skills during the first year, culminating in the ability to walk easily. After studying Figure 14, you should be able to order the milestones and describe the typical ages at which babies reach these milestones.
FIGURE 14 MILESTONES IN GROSS MOTOR DEVELOPMENT. The horizontal red bars indicate the range of ages at which most infants reach various milestones in gross motor development.(Photo credit left to right) ©Barbara Penoyar/Getty Images; ©StephaneHachey/Getty Images; ©Image Source/Alamy; ©Victoria Blackie/Getty Images; ©Digital Vision; ©Fotosearch/Getty Images;
©Corbis/PictureQuest; ©amaviael/123RF
A recent study found a number of factors that are linked to motor development in the first year of life (Flensborg-Madsen & Mortensen, 2017). Twelve developmental milestones were assessed, including grasping, rolling, sitting, and crawling; standing and walking; and overall mean of milestones. A larger size at birth (such as birth weight, birth length, and head circumference) was the aspect of pregnancy and delivery that showed the strongest link to reaching motor milestones earlier. Mother’s smoking in the last trimester of prenatal development was associated with reaching the motor milestones later. Also, increase in size (weight increase, length increase, and head increase) in the first year were related to reaching the motor milestones earlier. Breast feeding also was linked to reaching the milestones earlier.
However, the timing of these milestones, especially the later ones, may vary by as muchPage 123 as two to four months, and experiences can modify the onset of these accomplishments (Adolph, 2018). For example, since 1992, when pediatricians began recommending that parents place their babies on their backs to sleep, fewer babies crawled, and those who crawled did so later (Davis & others, 1998). Also, some infants do not follow the standard sequence of motor accomplishments. For example, many American infants never crawl on their belly or on their hands and knees. They may discover an idiosyncratic form of locomotion before walking, such as rolling or scooting, or they might never locomote until they are upright (Adolph & Robinson, 2015). In the African Mali tribe, most infants do not crawl (Bril, 1999). And in Jamaica, approximately one-fourth of babies skip crawling (Hopkins, 1991).
A baby is an angel whose wings decrease as his legs increase.
—French Proverb
According to Karen Adolph and Sarah Berger (2005), “the old-fashioned view that growth and motor development reflect merely the age-related output of maturation is, at best, incomplete. Rather, infants acquire new skills with the help of their caregivers in a real-world environment of objects, surfaces, and planes.”
Development in the Second Year The motor accomplishments of the first year bring increasing independence, allowing infants to explore their environment more extensively and to initiate interaction with others more readily. In the second year of life, toddlers become more motorically skilled and mobile. Motor activity during the second year is vital to the child’s competent development, and few restrictions, except for safety, should be placed on their adventures.
By 13 to 18 months, toddlers can pull a toy attached to a string and use their hands and legs to climb a number of steps. By 18 to 24 months, toddlers can walk quickly or run stiffly for a short distance, balance on their feet in a squatting position while playing with objects on the floor, walk backward without losing their balance, stand and kick a ball without falling, stand and throw a ball, and jump in place.
Can parents give their babies a head start on becoming physically fit and physically talented through structured exercise classes? Most infancy experts recommend against structured exercise classes for babies. But there are other ways to guide infants’ motor development.
Mothers in developing countries tend to stimulate their infants’ motor skills more than mothers in more developed countries (Hopkins, 1991; Karasik & others, 2015). In many African, Indian, and Caribbean cultures, mothers massage and stretch their infants during daily baths (Adolph, Karasik, & Tamis-LeMonda, 2010). Mothers in the Gusii culture of Kenya also encourage vigorous movement in their babies.
(Top) In the Algonquin culture in Quebec, Canada, babies are strapped to a cradle board for much of their infancy. (Bottom) In Jamaica, mothers massage and stretch their infants’ arms and legs. To what extent do cultural variations in the activity infants engage in influence the time at which they reach motor milestones?(Top) ©Michael Greenlar/The Image Works; (bottom) ©Pippa Hetherington/Earthstock/Newscom
Do these cultural variations make a difference in the infant’s motor development? When caregivers provide babies with physical guidance by physically handling them in special ways (such as stroking, massaging, or stretching) or by giving them opportunities for exercise, the infants often reach motor milestones earlier than infants whose caregivers have not provided these activities (Adolph, 2018; Adolph, Karasik, & Tamis-LeMonda, 2010; Karasik & others, 2015). For example, Jamaican mothers expect their infants to sit and walk alone two to three months earlier than English mothers do (Hopkins & Westra, 1990). And in sub-Saharan Africa, traditional practices in many villages involve mothers and siblings engaging babies in exercises, such as frequent exercise for trunk and pelvic muscles (Super & Harkness, 1997).
Many forms of restricted movement—such as Chinese sandbags, orphanage restrictions, and failure of caregivers to encourage movement in Budapest—have been found to produce substantial delays in motor development (Adolph, Karasik, & Tamis-LeMonda, 2010). In some rural Chinese provinces, for example, babies are placed in a bag of fine sand, which acts as a diaper and is changed once a day. The baby is left alone, face up, and is visited only when being fed by the mother (Xie & Young, 1999).
Some studies of swaddling (wrapping an infant tightly in a blanket) show slight delays in motor development, but other studies show no delays. Cultures that do swaddle infants usually do so early in the infant’s development when the infant is not yet mobile; when the infant becomes more mobile, swaddling decreases.
FINE MOTOR SKILLS
Whereas gross motor skills involve large muscle activity, fine motor skills involve finely tuned movements. Grasping a toy, using a spoon, buttoning a shirt, or any activity that requires finger dexterity demonstrates fine motor skills. Infants have hardly any control over fine motor skills at birth, but newborns do have many components of whatPage 124 will become finely coordinated arm, hand, and finger movements (McCormack, Hoerl, & Butterfill, 2012).
The onset of reaching and grasping marks a significant achievement in infants’ ability to interact with their surroundings (Rachwani & others, 2015). During the first two years of life, infants refine how they reach and grasp (Dosso, Herrera, & Boudreau, 2017; Needham, 2009). Initially, infants reach by moving their shoulders and elbows crudely, swinging their arms toward an object. Later, when infants reach for an object they move their wrists, rotate their hands, and coordinate their thumb and forefinger. Infants do not have to see their own hands in order to reach for an object (Clifton & others, 1993). Cues from muscles, tendons, and joints, not sight of the limb, guide reaching by 4-month-old infants. Recent research studies found that short-term training involving practice of reaching movements increased both preterm and full-term infants’ reaching for and touching objects (Cunha & others, 2016; Guimaraes & Tudelia, 2015).
A young girl uses a pincer grip to pick up puzzle pieces.©Newstockimages/SuperStock
Infants refine their ability to grasp objects by developing two types of grasps. Initially, infants grip with the whole hand, which is called the palmar grasp. Later, toward the end of the first year, infants also grasp small objects with their thumb and forefinger, which is called the pincer grip. Their grasping system is very flexible. They vary their grip on an object depending on its size, shape, and texture, as well as the size of their own hands relative to the object’s size. Infants grip small objects with their thumb and forefinger (and sometimes their middle finger too), but they grip large objects with all of the fingers of one hand or both hands.
Perceptual-motor coupling is necessary for the infant to coordinate grasping (Barrett, Traupman, & Needham, 2008). At different stages of development, infants use different perceptual systems to coordinate grasping. Four-month-old infants rely greatly on touch to determine how they will grip an object; 8-month-olds are more likely to use vision as a guide (Newell & others, 1989). This developmental change is efficient because vision lets infants preshape their hands as they reach for an object.
Experience plays a role in reaching and grasping. In a recent study, 3-month-olds who were not yet engaging in reaching behavior were provided with reaching experiences. These experiences were linked to increased object exploration and attention focusing skills at 15 months of age (Libertus, Joh, & Needham, 2016). In another study, 3-month-old infants participated in play sessions wearing “sticky mittens”—“mittens with palms that stuck to the edges of toys and allowed the infants to pick up the toys” (Needham, Barrett, & Peterman, 2002, p. 279) (see Figure 15). Infants who participated in sessions with the mittens grasped and manipulated objects earlier in their development than a control group of infants who did not receive the “mitten” experience. The infants who had worn the sticky mittens looked at the objects longer, swatted at them more during visual contact, and were more likely to mouth the objects. In a later study, 5-month-old infants whose parents trained them to use the sticky mittens for 10 minutes a day over a two-week period showed advances in their reaching behavior at the end of the two weeks (Libertus & Needham, 2010). Also, in a recent study, 3-month-old infants participated in active motor training using sticky mittens that allowed them to pick up toys, and these infants engaged in more sophisticated object exploration at 5.5 months of age (Wiesen, Watkins, & Needham, 2016).
FIGURE 15 INFANTS’ USE OF “STICKY MITTENS” TO EXPLORE OBJECTS. Amy Needham and her colleagues (2002) found that “sticky mittens” enhanced young infants’ object exploration skills.Courtesy of Dr. Amy Needham
Just as infants need to exercise their gross motor skills, they also need to exercise their fine motor skills (Needham, 2009). Especially when they can manage a pincer grip, infants delight in picking up small objects. Many develop the pincer grip and begin to crawl at about the same time, and infants at this time pick up virtually everything in sight, especially on the floor, and put the objects in their mouth. Thus, parents need to be vigilant in regularly monitoring what objects are within the infant’s reach (Keen, 2005).
Rachel Keen (2011; Keen, Lee, & Adolph, 2014) emphasizes that tool use is an excellent context for studying problem solving in infants because tool use provides information about how infants plan to reach a goal. Researchers in this area have studied infants’ intentional actions, which range from picking up a spoon in different orientations to retrieving rakes from inside tubes. One study explored motor origins of tool use by assessing developmental changes in banging movements in 6- to 15-month-olds (Kahrs, Jung, & Lockman, 2013). In this study, younger infants were inefficient and variable when banging an object but by one year of age infants showed consistent straight up-and-down hand movements that resulted in precise aiming and consistent levels of force.
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Review Connect Reflect
LG2 Describe infants’ motor development.
Review
- What is the dynamic systems view?
- What are some reflexes that infants have?
- How do gross motor skills develop in infancy?
- How do fine motor skills develop in infancy?
Connect
- What are the differences between the grasping reflex present at birth and the fine motor grasping skills an infant develops between 4 and 12 months of age?
Reflect Your Own Personal Journey of Life
- Think of a motor skill that you perform. How would dynamic systems theory explain your motor skill performance?
3 Sensory and Perceptual Development
LG3 Summarize the course of sensory and perceptual development in infancy.
What Are Sensation and Perception?
The Ecological View
Visual Perception
Other Senses
Intermodal Perception
Nature, Nurture, and Perceptual Development
Perceptual-Motor
Coupling
How do sensations and perceptions develop? Can a newborn see? If so, what can it perceive? What about the other senses—hearing, smell, taste, and touch? What are they like in the newborn, and how do they develop? Can an infant put together information from two modalities, such as sight and sound? These are among the intriguing questions that we will explore in this section.
WHAT ARE SENSATION AND PERCEPTION?
How does a newborn know that her mother’s skin is soft rather than rough? How does a 5-year-old know what color his hair is? Infants and children “know” these things as a result of information that comes through the senses. Without vision, hearing, touch, taste, and smell, we would be isolated from the world; we would live in dark silence, a tasteless, colorless, feelingless void.
Sensation occurs when information interacts with sensory receptors—the eyes, ears, tongue, nostrils, and skin. The sensation of hearing occurs when waves of pulsating air are collected by the outer ear and transmitted through the bones of the inner ear to the auditory nerve. The sensation of vision occurs as rays of light contact the eyes, become focused on the retina, and are transmitted by the optic nerve to the visual centers of the brain.
The experiences of the first three years of life are almost entirely lost to us, and when we attempt to enter into a small child’s world, we come as foreigners who have forgotten the landscape and no longer speak the native tongue.
—Selma Fraiberg
Developmentalist and Child Advocate, 20th Century
Perception is the interpretation of what is sensed. The air waves that contact the ears might be interpreted as noise or as musical sounds, for example. The physical energy transmitted to the retina of the eye might be interpreted as a particular color, pattern, or shape, depending on how it is perceived.
THE ECOLOGICAL VIEW
For the past several decades, much of the research on perceptual development in infancy has been guided by the ecological view of Eleanor and James J. Gibson (E. J. Gibson, 1969, 1989, 2001; J. J. Gibson, 1966, 1979). They argue that we do not have to take bits and pieces of data from sensations and build up representations of the world in our minds. Instead, our perceptual system can select from the rich information that the environment itself provides.
According to the Gibsons’ ecological view, we directly perceive informationPage 126 that exists in the world around us. This view is called ecological “because it connects perceptual capabilities to information available in the world of the perceiver” (Kellman & Arterberry, 2006, p. 112). Thus, perception brings us into contact with the environment so we can interact with and adapt to it (Kretch & Adolph, 2017). Perception is designed for action. Perception gives people information such as when to duck, when to turn their bodies as they move through a narrow passageway, and when to put their hands up to catch something.
In the Gibsons’ view, objects have affordances, which are opportunities for interaction offered by objects that fit within our capabilities to perform activities. A pot may afford you something to cook with, and it may afford a toddler something to bang. Adults typically know when a chair is appropriate for sitting, when a surface is safe for walking, or when an object is within reach. An infant who runs down a steep slope or crawls across a narrow beam is determining the affordances of the slope or beam. We directly and accurately perceive these affordances by sensing information from the environment—the light or sound reflecting from the surfaces of the world—and from our own bodies through muscle receptors, joint receptors, and skin receptors, for example (Adolph & Kretch, 2015).
How would you use the Gibsons’ ecological theory of perception and the concept of affordance to explain the role that perception is playing in this baby’s activity?©Ryan KC Wong/Getty Images
An important developmental question is: What affordances can infants or children detect and use? In one study, for example, when babies who could walk were faced with a squishy waterbed, they stopped and explored it, then chose to crawl rather than walk across it (Gibson & others, 1987). They combined perception and action to adapt to the demands of the task.
Similarly, as we described earlier in the section on motor development, infants who were just learning to crawl or just learning to walk were less cautious when confronted with a steep slope than experienced crawlers or walkers were (Adolph, 1997). The more experienced crawlers and walkers perceived that a slope affords the possibility for not only faster locomotion but also for falling. Again, infants coupled perception and action to make a decision about what to do in their environment. Through perceptual development, children become more efficient at discovering and using affordances (Kretch & Adolph, 2017).
Studying infants’ perceptions has not been an easy task. For instance, if newborns have limited communication abilities and are unable to verbalize what they are seeing, hearing, smelling, and so on, how can we study their perception? Connecting Through Research describes some of the ingenious ways researchers study infants’ perceptions.
VISUAL PERCEPTION
What do newborns see? How does visual perception develop in infancy?
Visual Acuity and Human Faces Psychologist William James (1890/1950) called the newborn’s perceptual world a “blooming, buzzing confusion.” More than a century later, we can safely say that he was wrong (Bremner & others, 2017; Damon & others, 2018; Singarajah & others, 2017; Weatherhead & White, 2017). Even the newborn perceives a world with some order. That world, however, is far different from the one perceived by the toddler or the adult.
Just how well can infants see? At birth, the nerves and muscles and lens of the eye are still developing. As a result, newborns cannot see small things that are far away. The newborn’s vision is estimated to be 20/240 on the well-known Snellen chart used for eye examinations, which means that a newborn can see at 20 feet what an adult with normal vision can see at 240 feet (Aslin & Lathrop, 2008). In other words, an object 20 feet away is only as clear to the newborn as it would be if it were 240 feet away from an adult with normal vision (20/20). By 6 months of age, though, on average vision is 20/40 (Aslin & Lathrop, 2008).
Faces are possibly the most important visual stimuli in children’s social environment, and it is important that they extract key information from others’ faces (Singarajah & others, 2017; Sugden & Moulson, 2017). Infants show an interest in human faces soon after birth (Johnson & Hannon, 2015). Research shows that within hours after infants are born, they prefer to look at faces rather than other objects and to look at attractive faces more than at unattractive ones (Lee & others, 2013).
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connecting through research
How Can Newborns’ Perception Be Studied?
The creature has poor motor coordination and can move itself only with great difficulty. Although it cries when uncomfortable, it uses few other vocalizations. In fact, it sleeps most of the time, about 16 to 17 hours a day. You are curious about this creature and want to know more about what it can do. You think to yourself, “I wonder if it can see. How could I find out?”
You obviously have a communication problem with the creature. You must devise a way that will allow the creature to “tell” you that it can see. While examining the creature one day, you make an interesting discovery. When you move an object horizontally in front of the creature, its eyes follow the object’s movement.
The creature’s eye movement suggests that it has at least some vision. In case you haven’t already guessed, the creature you have been reading about is the human infant, and the role you played is that of a researcher interested in devising techniques to learn about the infant’s visual perception. After years of work, scientists have developed research methods and tools sophisticated enough to examine the subtle abilities of infants and to interpret their complex actions (Bendersky & Sullivan, 2007).
Following are six research techniques that are used to study sensory and perceptual development: (1) visual preference method, (2) habituation/dishabituation, (3) high-amplitude sucking, (4) orienting response, (5) eye tracking, and (6) equipment.
Visual Preference Method
Robert Fantz (1963) was a pioneer in this effort. Fantz made an important discovery that advanced the ability of researchers to investigate infants’ visual perception: Infants look at different things for different lengths of time. Fantz placed an infant in a “looking chamber,” which had two visual displays on the ceiling above the infant’s head. An experimenter viewed the infant’s eyes by looking through a peephole. If the infant was fixating on one of the displays, the experimenter could see the display’s reflection in the infant’s eyes. This allowed the experimenter to determine how long the infant looked at each display. Fantz (1963) found that infants only 2 days old looked longer at patterned stimuli, such as faces and concentric circles, than at red, white, or yellow discs. Infants 2 to 3 weeks old also preferred to look at patterns—a face, a piece of printed matter, or a bull’s-eye—longer than at red, yellow, or white discs (see Figure 16). Fantz’s research method—studying whether infants can distinguish one stimulus from another by measuring the length of time they attend to different stimuli—is referred to as the visual preference method.
FIGURE 16 FANTZ’S EXPERIMENT ON INFANTS’ VISUAL PERCEPTION. (a) Infants 2 to 3 weeks old preferred to look at some stimuli more than others. In Fantz’s experiment, infants preferred to look at patterns rather than at color or brightness. For example, they looked longer at a face, a piece of printed matter, or a bull’s-eye than at red, yellow, or white discs. (b) Fantz used a “looking chamber” to study infants’ perception of stimuli.©David Linton, Courtesy of the Linton Family
Habituation and Dishabituation
Another way that researchers have studied infant perception is to present a stimulus (such as a sight or a sound) a number of times. If the infant decreases its response to the stimulus after several presentations, it indicates that the infant is no longer interested in looking at the stimulus. If the researcher now presents a new stimulus, the infant’s response will recover—indicating the infant can discriminate between the old and new stimulus (Messinger & others, 2017).
Habituation is the name given to decreased responsiveness to a stimulus after repeated presentations of the stimulus. Dishabituation is the recovery of a habituated response after a change in stimulation. Newborn infants can habituate to repeated sights, sounds, smells, or touches (Rovee-Collier, 2004). Among the measures researchersPage 128 use in habituation studies are sucking behavior (sucking stops when the young infant attends to a novel object), heart and respiration rates, and the length of time the infant looks at an object. Figure 17 shows the results of one study of habituation and dishabituation with newborns (Slater, Morison, & Somers, 1988).
FIGURE 17 HABITUATION AND DISHABITUATION. In the first part of one study, (a) 7-hour-old newborns were shown a stimulus. As indicated, the newborns looked at it an average of 41 seconds when it was first presented to them (Slater, Morison, & Somers, 1988). Over seven more presentations of the stimulus, they looked at it less and less. In the second part of the study, (b) infants were presented with both the familiar stimulus to which they had just become habituated and a new stimulus (which was rotated 90 degrees). The newborns looked at the new stimulus three times as long as the familiar stimulus.
High-Amplitude Sucking
To assess an infant’s attention to sound, researchers often use a method called high-amplitude sucking. In this method, infants are given a nonnutritive nipple to suck, and the nipple is connected to a sound-generating system. The researcher computes a baseline high-amplitude sucking rate in a one-minute silent period. Following the baseline, presentation of a sound is made contingent on the rate of high-amplitude sucking. Initially babies suck frequently so the sound occurs often. Gradually they lose interest in hearing the same sound, so they begin to suck less often. Then the researcher changes the sound that is being presented. If the babies renew their vigorous sucking, the inference is that they have noticed the sound change and are sucking more because they want to hear the interesting new sound (Menn & Stoel-Gammon, 2009).
The Orienting Response and Eye-Tracking
A technique that can be used to determine whether an infant can see or hear is the orienting response, which involves turning one’s head toward a sight or sound. However, the most important recent advance in measuring infant perception is the development of sophisticated eye-tracking equipment (Boardman & Fletcher-Watson, 2017; Kretch & Adolph, 2017; van Renswoude & others, 2018). Eye-tracking consists of measuring eye movements that follow (track) a moving object and can be used to evaluate an infant’s early visual ability, or a startle response can determine an infant’s reaction to a noise (Bendersky & Sullivan, 2007). Figure 18 shows an infant wearing an eye-tracking headgear in a recent study on visually guided motor behavior and social interaction. Most studies of infant development use remote optics eye trackers that have a camera that is not attached to the infant’s head.
FIGURE 18 AN INFANT WEARING EYE-TRACKING HEADGEAR. Photo from Karen Adolph’s laboratory at New York University.Courtesy of Dr. Karen Adolph, New York University
One of the main reasons that infant perceptionPage 129 researchers are so enthusiastic about the availability of sophisticated eye-tracking equipment is that looking time is among the most important measures of infant perceptual and cognitive development (Aslin, 2012). The new eye-tracking equipment allows for far greater precision in assessing various aspects of infant looking and gaze than is possible with human observation (Boardman & Fletcher-Watson, 2017; Law & others, 2018). Among the areas of infant perception in which eye-tracking equipment is being used are attention (Jia & others, 2017; Meng, Uto, & Hashiya, 2017), memory (Kingo & Krojgaard, 2015), and face processing (Chhaya & others, 2018). Further, eye-tracking equipment is improving our understanding of atypically developing infants, such as those who have autism or who were born preterm (Falck-Ytter & others, 2018; Finke, Wilkinson, & Hickerson, 2017; Liberati & others, 2017).
One eye-tracking study shed light on the effectiveness of TV programs and DVDs that claim to educate infants (Kirkorian, Anderson, & Keen, 2012). In this study, 1-year-olds, 4-year-olds, and adults watched Sesame Street and the eye-tracking equipment recorded precisely what they looked at on the screen. The 1-year-olds were far less likely to consistently look at the same part of the screen as their older counterparts, suggesting that the 1-year-olds showed little understanding of the Sesame Street video but instead were more likely to be attracted by what was salient than by what was relevant.
Equipment
Technology can facilitate the use of most methods for investigating the infant’s perceptual abilities. Video-recording equipment allows researchers to investigate elusive behaviors. High-speed computers make it possible to perform complex data analysis in minutes. Other equipment records respiration, heart rate, body movement, visual fixation, and sucking behavior, which provide clues to what the infant is perceiving. For example, some researchers use equipment that detects whether a change in infants’ respiration follows a change in the pitch of a sound. If so, it suggests that the infants heard the pitch change.
Scientists have had to be very creative when assessing the development of infants, discovering ways to “interview” them even though they cannot yet talk. Other segments of the population, such as adults who have suffered from a stroke, have difficulty communicating verbally. What kinds of methods or equipment do you think researchers might use to evaluate their perceptual abilities?
Figure 19 shows a computer estimation of what a picture of a face looks like to an infant at different ages from a distance of about 6 inches. Infants spend more time looking at their mother’s face than a stranger’s face as early as 12 hours after being born (Bushnell, 2003). By 3 months of age, infants (1) match voices to faces, (2) distinguish between male and female faces, and (3) discriminate between faces of their own ethnic group and those of other ethnic groups (Gaither, Pauker, & Johnson, 2012; Kelly & others, 2005, 2007; Lee & others, 2013; Liu & others, 2011, 2015).
FIGURE 19 VISUAL ACUITY DURING THE FIRST MONTHS OF LIFE. The four photographs represent a computer estimation of what a picture of a face looks like to a 1-month-old, 2-month-old, 3-month-old, and 1-year-old (which approximates the visual acuity of an adult).©Kevin Peterson/Getty Images; Simulation by Vischek
Experience plays an important role in face processing in infancy and later in development. One aspect of this experience involves the concept of perceptual narrowing, in which infants are more likely to distinguish between faces to which they have been exposed than faces that they have never seen before (Kobayashi & others, 2018; Minar & Lewkowicz, 2018; Tham, Bremner, & Hayes, 2017).
Color Vision The infant’s color vision also improves (Yang & others, 2015). By 8 weeks, and possibly as early as 4 weeks, infants can discriminate between some colors (Kelly, Borchert, & Teller, 1997). By 4 months of age, they have color preferencesPage 130 that mirror adults’ in some cases, preferring saturated colors such as royal blue over pale blue, for example (Bornstein, 1975). In part, the changes in vision described here reflect biological origins and maturation (Skelton & others, 2017). Experience, however, is also necessary for color vision to develop normally (Sugita, 2004).
Perceptual Constancy Some perceptual accomplishments are especially intriguing because they indicate that the infant’s perception goes beyond the information provided by the senses (Bremner & others, 2017). This is the case in perceptual constancy, in which sensory stimulation is changing but perception of the physical world remains constant. If infants did not develop perceptual constancy, each time they saw an object at a different distance or in a different orientation, they would perceive it as a different object. Thus, the development of perceptual constancy allows infants to perceive their world as stable. Two types of perceptual constancy are size constancy and shape constancy.
Size constancy is the recognition that an object remains the same even though the retinal image of the object changes as you move toward or away from the object. The farther away from us an object is, the smaller its image is on our eyes. Thus, the size of an object on the retina is not sufficient to tell us its actual size. For example, you perceive a bicycle standing right in front of you as smaller than the car parked across the street, even though the bicycle casts a larger image on your eyes than the car does. When you move away from the bicycle, you do not perceive it to be shrinking even though its image on your retinas shrinks; you perceive its size as constant.
But what about babies? Do they have size constancy? Researchers have found that babies as young as 3 months of age show size constancy (Bower, 1966; Day & McKenzie, 1973). However, at 3 months of age, this ability is not full-blown. It continues to develop until 10 or 11 years of age (Kellman & Banks, 1998).
Shape constancy is the recognition that an object remains the same shape even though its orientation to us changes. Look around the room you are in right now. You likely see objects of varying shapes, such as tables and chairs. If you get up and walk around the room, you will see these objects from different sides and angles. Even though your retinal image of the objects changes as you walk and look, you will still perceive the objects as having the same shape.
Do babies have shape constancy? As with size constancy, researchers have found that babies as young as 3 months of age have shape constancy (Bower, 1966; Day & McKenzie, 1973). Three-month-old infants, however, do not have shape constancy for irregularly shaped objects such as tilted planes (Cook & Birch, 1984).
Perception of Occluded Objects Look around where you are now. You likely see that some objects are partly occluded by other objects that are in front of them—possibly a desk behind a chair, some books behind a computer, or a car parked behind a tree. Do infants perceive an object as complete when it is occluded by an object in front of it?
In the first two months of postnatal development, infants don’t perceive occluded objects as complete; instead, they perceive only what is visible (Johnson & Hannon, 2015). Beginning at about 2 months of age, infants develop the ability to perceive that occluded objects are whole (Slater, Field, & Hernandez-Reif, 2007). How does perceptual completion develop? In Scott Johnson’s research (2010, 2011, 2013), learning, experience, and self-directed exploration via eye movements play key roles in the development of perceptual completion in young infants.
Many objects that are occluded appear and disappear behind closer objects, as when you are walking down the street and see cars appear and disappear behind buildings as they move or you move. Infants develop the ability to track briefly occluded moving objects at about 3 to 5 months of age (Bertenthal, 2008). One study explored the ability of 5- to 9-month-old infants to track moving objects that disappeared gradually behind an occluded partition, disappeared abruptly, or imploded (shrank quickly in size) (Bertenthal, Longo, & Kenny, 2007) (see Figure 20). In this study, the infants were more likely to accurately predict the reappearance of the moving object when it disappeared gradually than when it vanished abruptly or imploded.
FIGURE 20 INFANTS’ PREDICTIVE TRACKING OF A BRIEFLY OCCLUDED MOVING BALL. The top picture shows the visual scene that infants experienced. At the beginning of each event, a multicolored ball bounced up and down with an accompanying bouncing sound, and then rolled across the floor until it disappeared behind the partition. The other three pictures show the three stimulus events that the 5- to 9-month-old infants experienced: (a) Gradual occlusion—the ball gradually disappears behind the right side of the occluding partition located in the center of the display. (b) Abrupt occlusion—the ball abruptly disappears when it reaches the location of the white circle and then abruptly reappears two seconds later at the location of the second white circle on the other side of the occluding partition. (c) Implosion—the rolling ball quickly decreases in size as it approaches the occluding partition and rapidly increases in size as it reappears on the other side of the occluding partition.
Depth Perception Might infants even perceive depth? To investigate this question, Eleanor Gibson and Richard Walk (1960) constructed a miniature cliff with a drop-off covered by glass in their laboratory. They placed infants on the edge of this visual cliff and had their mothers coax them to crawl onto the glass (see Figure 21). Most infants would not crawl out on the glass, choosing instead to remain on the shallow side, an indication that they could perceive depth.
FIGURE 21 EXAMINING INFANTS’ DEPTH PERCEPTION ON THE VISUAL CLIFF. Eleanor Gibson and Richard Walk (1960) found that most infants would not crawl out on the glass, which, according to Gibson and Walk, indicated that they had depth perception. However, some critics point out that the visual cliff is a better indication of the infant’s social referencing and fear of heights than of the infant’s perception of depth.©Mark Richard/PhotoEditPage 131
OTHER SENSES
Other sensory systems besides vision also develop during infancy. We will explore development in hearing, touch and pain, smell, and taste.
Hearing During the last two months of pregnancy, as the fetus nestles in its mother’s womb, it can hear sounds such as the mother’s voice, music, and so on (Kisilevsky & others, 2009). Two psychologists wanted to find out if a fetus who heard Dr. Seuss’ classic story The Cat in the Hat while still in the mother’s womb would prefer hearing the story after birth (DeCasper & Spence, 1986). During the last months of pregnancy, 16 women read The Cat in the Hat to their fetuses. Then shortly after the babies were born, they listened to recordings of their mothers reading either The Cat in the Hat or a story with a different rhyme and pace, The King, the Mice and the Cheese (which was not read to them during prenatal development). The infants sucked on a nipple in a different way when they listened to the recordings of the two stories, suggesting that the infants recognized the pattern and tone of The Cat in the Hat (see Figure 22). This study illustrates not only that a fetus can hear but also that it has a remarkable ability to learn and remember even before birth. An fMRI study confirmed capacity of the fetus to hear at 33 to 34 weeks into the prenatal period by assessing fetal brain response to auditory stimuli (Jardri & others, 2012).
FIGURE 22 HEARING IN THE WOMB. (a) Pregnant mothers read The Cat in the Hat to their fetuses during the last few months of pregnancy. (b) When they were born, the babies preferred listening to a recording of their mothers reading The Cat in the Hat, as evidenced by their sucking on a nipple that produced this recording, rather than another story, The King, the Mice and the Cheese.(a) ©McGraw Hill Companies/Jill Braaten, Photographer;
(b) Courtesy of Dr. Melanie J. Spence
The fetus can also recognize the mother’s voice, as one study demonstrated (Kisilevsky & others, 2003). Sixty term fetuses (mean gestational age, 38.4 weeks) were exposed to a tape recording either of their mother or of a female stranger reading a passage. The sounds of the tape were delivered through a loudspeaker held just above the mother’s abdomen. Fetal heart rate increased in response to the mother’s voice but decreased in response to the stranger’s voice.
What kind of changes in hearing take place during infancy? They involve perception of a sound’s loudness, pitch, and localization:
- Loudness. Immediately after birth, infants cannot hear soft sounds quite as well as adults can; a stimulus must be louder to be heard by a newborn than by an adult (Trehub & others, 1991). For example, an adult can hear a whisper from about 4 to 5 feet away, but a newborn requires that sounds be closer to a normal conversational level to be heard at that distance. By three months of age, infants’ perception of sounds improves, although some aspects of loudness perception do not reach adult levels until 5 to 10 years of age (Trainor & He, 2013).
- Pitch. Infants are also less sensitive to the pitch of a sound than adults are. Pitch is the perception of the frequency of a sound. A soprano voice sounds high-pitched, a bass voice low-pitched. Infants are less sensitive to low-pitched sounds and are more likely to hear high-pitched sounds (Aslin, Jusczyk, & Pisoni, 1998). One study revealed that by 7 months of age, infants can process simultaneous pitches when they hear voices but they are more likely to encode the higher-pitched voice (Marie & Trainor, 2013). By 2 years of age, infants have considerably improved their ability to distinguish sounds of different pitch.
- Localization. Even newborns can determine the general location from which a sound is coming, but by 6 months of age, they are more proficient at localizing sounds or detecting their origins. Their ability to localize sounds continues to improve during the second year (Burnham & Mattock, 2010).
Although infants can process variations in sound loudness, pitch, and localization, these aspects of hearing continue to improve during the childhood years (Trainor & He, 2013).
Touch and Pain Do newborns respond to touch? Can they feel pain?
Newborns do respond to touch. A touch to the cheek produces a turning of the head; a touch to the lips produces sucking movements.
Regular gentle tactile stimulation prenatally may have positive developmental outcomes. For example, a recent study found that 3-month-olds who had regular gentle tactile stimulation as fetuses were more likely to have an easy temperament than their counterparts who had irregular gentle or no tactile stimulation as fetuses (Wang, Hua, & Xu, 2015).
Newborns can also feel painPage 132 (Bellieni & others, 2016). If you have a son and consider whether he should be circumcised, the issue of an infant’s pain perception probably will become important to you. Circumcision is usually performed on infant boys about the third day after birth. Will your son experience pain if he is circumcised when he is 3 days old? An investigation by Megan Gunnar and her colleagues (1987) found that newborn infant males cried intensely during circumcision. Circumcised infants also display amazing resiliency. Within several minutes after the surgery, they can nurse and interact in a normal manner with their mothers. And, if allowed to, the newly circumcised newborn drifts into a deep sleep, which seems to serve as a coping mechanism.
developmental connection
Sensation and Perception
Kangaroo care and massage therapy are associated with many positive outcomes in preterm and low birth weight infants. Connect to “Prenatal Development and Birth.”
For many years, doctors performed operations on newborns without anesthesia. This practice was accepted because of the dangers of anesthesia and because of the supposition that newborns do not feel pain. As researchers demonstrated that newborns can feel pain, the practice of operating on newborns without anesthesia has been challenged. Anesthesia now is used in some circumcisions (Morris & others, 2012).
Recent neuroimaging studies indicate that newborn infants likely experience some aspects of pain similarly to adults (Ranger & Grunau, 2015). Magnetic resonance imaging (MRI) studies of adults have found that there is a complex brain activity network that underlies pain, which is called the “pain matrix.” The pain matrix brain regions consist of areas located in the thalamus, somatosensory cortex, and amygdala (Denk, McMahon, & Tracey, 2014). In a recent study, researchers discovered that 18 of the 20 regions in the adult pain matrix also are present in the newborn’s pain matrix (Goksan & others, 2015). However, a major brain region in the adult’s pain matrix that was not present in the infant’s was the amygdala, which involves emotional responses. Also in this study, the MRI information revealed that the pain threshold in newborns occurs at a lower level of stimulation than for adults, confirming newborns’ heightened pain sensitivity that has been found in earlier behavioral studies. And in a recent study, kangaroo care was effective in reducing neonatal pain, especially indicated by the significantly lower level of crying when the care was instituted after the newborn’s blood had been drawn by a heel stick (Seo, Lee, & Ahn, 2016).
Smell Newborns can differentiate odors (Doty & Shah, 2008). The expressions on their faces seem to indicate that they like the way vanilla and strawberries smell but do not like the way rotten eggs and fish smell (Steiner, 1979). In one investigation, 6-day-old infants who were breast fed showed a clear preference for smelling their mother’s breast pad rather than a clean breast pad (MacFarlane, 1975) (see Figure 23). However, when they were 2 days old they did not show this preference, indicating that they require several days of experience to recognize this odor.
FIGURE 23 NEWBORNS’ PREFERENCE FOR THE SMELL OF THEIR MOTHER’S BREAST PAD. In the experiment by MacFarlane (1975), 6-day-old infants preferred to smell their mother’s breast pad rather than a clean one that had never been used, but 2-day-old infants did not show this preference, indicating that odor preference requires several days of experience to develop.©Jean Guichard
Taste Sensitivity to taste is present even before birth (Doty & Shah, 2008). Human newborns learn tastes prenatally through the amniotic fluid and in breast milk after birth (Beauchamp & Mennella, 2009). In one study, even at only 2 hours of age, babies made different facial expressions when they tasted sweet, sour, and bitter solutions (Rosenstein & Oster, 1988). At about 4 months of age, infants begin to prefer salty tastes, which as newborns they had found to be aversive (Doty & Shah, 2008).
INTERMODAL PERCEPTION
Imagine yourself playing basketball or tennis. You are experiencing many visual inputs: the ball coming and going, other players moving around, and so on. However, you are experiencing many auditory inputs as well: the sound of the ball bouncing or being hit, the grunts and groans of other players, and so on. There is good correspondence between much of the visual and auditory information: When you see the ball bounce, you hear a bouncing sound; when a player stretches to hit a ball, you hear a groan. When you look at and listen to what is going on, you do not experience just the sounds or just the sights—you put all these things together. You experience a unitary episode. This is intermodal perception, which involves integrating information from two or more sensory modalities, such as vision and hearing (Bremner & Spence, 2017; Hannon, Schachner, & Nave-Blodgett, 2017; Nomikou, Koke, & Rohlfing, 2017). Most perception is intermodal (Bahrick, 2010).
Early, exploratory forms of intermodal perception exist even in newborns (Bahrick & Hollich, 2008; Bremner, 2017; Guellai & others, 2016). For example, newborns turn their eyes and their head toward the sound of a voice or rattle when the soundPage 133 is maintained for several seconds (Clifton & others, 1981), but the newborn can localize a sound and look at an object only in a crude way (Bechtold, Bushnell, & Salapatek, 1979). These early forms of intermodal perception become sharpened with experience in the first year of life (Bremner & Spence, 2017; Kirkham & others, 2012). In one study, infants as young as 3 months old looked longer at their parents when they also heard their voices (Spelke & Owsley, 1979). Thus, even young infants can coordinate visual-auditory information involving people.
What is intermodal perception? Which two senses is this infant using to integrate information about the blocks?©Kaori Ando/Getty Images
Can young infants put vision and sound together as precisely as adults do? In the first six months, infants have difficulty connecting sensory input from different modes, but in the second half of the first year they show an increased ability to make this connection mentally (Hannon, Schachner, & Nave-Blodgett, 2017).
NATURE, NURTURE, AND PERCEPTUAL DEVELOPMENT
Now that we have discussed many aspects of perceptual development, let’s explore one of developmental psychology’s key issues in relation to perceptual development: the nature-nurture issue. There has been a longstanding interest in how strongly infants’ perception is influenced by nature or nurture (Bremner, 2017; Chen & others, 2017; Johnson & Hannon, 2015). In the field of perceptual development, nature proponents are referred to as nativists and those who emphasize learning and experience are called empiricists.
In the nativist view, the ability to perceive the world in a competent, organized way is inborn or innate. A completely nativist view of perceptual development no longer is accepted in developmental psychology.
The Gibsons argued that a key question in infant perception is what information is available in the environment and how infants learn to generate, differentiate, and discriminate the information—certainly not a nativist view. The Gibsons’ ecological view also is quite different from Piaget’s constructivist view. According to Piaget, much of perceptual development in infancy must await the development of a sequence of cognitive stages for infants to construct more complex perceptual tasks. Thus, in Piaget’s view the ability to perceive size and shape constancy, a three-dimensional world, intermodal perception, and so on, develops later in infancy than the Gibsons envision.
The longitudinal research of Daphne Maurer and her colleagues (Chen & others, 2017; Lewis & Maurer, 2005, 2009; Maurer, 2016; Maurer & Lewis, 2013; Maurer & others, 1999) has focused on infants born with cataracts—a thickening of the lens of the eye that causes vision to become cloudy, opaque, and distorted and thus severely restricts infants’ ability to experience their visual world. Studying infants whose cataracts were removed at different points in development, they discovered that those whose cataracts were removed and new lenses placed in their eyes in the first several months after birth showed a normal pattern of visual development. However, the longer the delay in removing the cataracts, the more their visual development was impaired. In their research, Maurer and her colleagues (2007) have found that experiencing patterned visual input early in infancy is important for holistic and detailed face processing after infancy. Maurer’s research program illustrates how deprivation and experience influence visual development, revealing an early sensitive period when visual input is necessary for normal visual development (Chen & others, 2017; Maurer & Lewis, 2013).
Today, it is clear that just as an extreme nativist position on perceptual development is unwarranted, an extreme empiricist position also is unwarranted. Much of very early perception develops from innate (nature) foundations, and the basic foundation of many perceptual abilities can be detected in newborns (Bornstein, Arterberry, & Mash, 2015). However, as infants develop, environmental experiences (nurture) refine or calibrate many perceptual functions, and they may be the driving force behind some functions (Amso & Johnson, 2010). The accumulation of experience with and knowledge about their perceptual world contributes to infants’ ability to process coherent perceptions of people and things (Bremner & others, 2016; Johnson & Hannon, 2015). Thus, a full portrait of perceptual development includes the influence of nature, nurture, and a developing sensitivity to information (Bremner & others, 2016; Chen & others, 2017; Maurer, 2016).
What roles do nature and nurture play in the infant’s perceptual development?©Boris Ryaposov/ShutterstockPage 134
PERCEPTUAL-MOTOR COUPLING
As we come to the end of this chapter, we return to the important theme of perceptual-motor coupling. The distinction between perceiving and doing has been a time-honored tradition in psychology. However, a number of experts on perceptual and motor development question whether this distinction makes sense (Adolph, 2018; Thelen & Smith, 2006). The main thrust of research in Esther Thelen’s dynamic systems approach is to explore how people assemble motor behaviors for perceiving and acting. The main theme of the ecological approach of Eleanor and James J. Gibson is to discover how perception guides action. Action can guide perception, and perception can guide action. Only by moving one’s eyes, head, hands, and arms and by moving from one location to another can an individual fully experience his or her environment and learn how to adapt to it. Perception and action are coupled (Kretch & Adolph, 2018).
How are perception and action coupled in children’s development?©Kevin Liu/Getty Images
Babies, for example, continually coordinate their movements with perceptual information to learn how to maintain balance, reach for objects in space, and move across various surfaces and terrains (Bremner & others, 2017). They are motivated to move by what they perceive. Consider the sight of an attractive toy across the room. In this situation, infants must perceive the current state of their bodies and learn how to use their limbs to reach the toy. Although their movements at first are awkward and uncoordinated, babies soon learn to select patterns that are appropriate for reaching their goals.
Equally important is the other part of the perception-action coupling. That is, action educates perception (Adolph, 2018). For example, watching an object while exploring it manually helps infants to determine its texture, size, and hardness. Locomoting in the environment teaches babies about how objects and people look from different perspectives, or whether various surfaces will support their weight.
The infant is by no means as helpless as it looks and is quite capable of some very complex and important actions.
—Herb Pick
Developmental Psychologist, University of Minnesota
How do infants develop new perceptual-motor couplings? Recall from our discussion earlier in this chapter that in the traditional view of Gesell, infants’ perceptual-motor development is prescribed by a genetic plan to follow a fixed and sequential progression of stages in development. The genetic determination view has been replaced by the dynamic systems view that infants learn new perceptual-motor couplings by assembling skills for perceiving and acting. New perceptual-motor coupling is not passively accomplished; rather, the infant actively develops a skill to achieve a goal within the constraints set by the infant’s body and the environment (Kretch & Adolph, 2018).
Children perceive in order to move and move in order to perceive. Perceptual and motor development do not occur in isolation from each other but instead are coupled.
Review Connect Reflect
LG3 Summarize the course of sensory and perceptual development in infancy.
Review
- What are sensation and perception?
- What is the ecological view of perception?
- How does visual perception develop in infancy?
- How do hearing, touch and pain, smell, and taste develop in infancy?
- What is intermodal perception?
- What roles do nature and nurture play in perceptual development?
- How is perceptual-motor development coupled?
Connect
- Perceptual-motor coupling was discussed in the previous section as well as in this section. Describe how this concept could be linked to the concept of nature versus nurture.
Reflect Your Own Personal Journey of Life
- How much sensory stimulation would you provide your own baby? A little? A lot? Could you overstimulate your baby? Explain.
Page 135
topical connections looking forward
In the next chapter, you will read about the remarkable cognitive changes that characterize infant development and how soon infants are able to competently process information about their world. Advances in infants’ cognitive development—together with the development of the brain and perceptual-motor advances discussed in this chapter—allow infants to adapt more effectively to their environment. Later in this text, we will further explore physical development when we examine how children progress through early childhood (ages 3 to 5). Young children’s physical development continues to change and to become more coordinated in early childhood, although gains in height and weight are not as dramatic in early childhood as in infancy.
reach your learning goals
Physical Development in Infancy
1 Physical Growth and Development in Infancy
LG1 Discuss physical growth and development
in infancy.
Patterns of Growth
Height and Weight
The Brain
Sleep
Nutrition
- The cephalocaudal pattern is the sequence in which growth proceeds from top to bottom. The proximodistal pattern is the sequence in which growth starts at the center of the body and moves toward the extremities.
- The average North American newborn is 20 inches long and weighs 7.6 pounds. Infants grow about 1 inch per month in the first year and nearly triple their weight by their first birthday. The rate of growth slows in the second year.
- One of the most dramatic changes in the brain in the first two years of life is dendritic spreading, which increases the connections between neurons. Myelination, which speeds the conduction of nerve impulses, continues through infancy and even into adolescence.
- The cerebral cortex has two hemispheres (left and right). Lateralization refers to specialization of function in one hemisphere or the other. Early experiences play an important role in brain development.
- Neural connections are formed early in an infant’s life. Before birth, genes mainly direct neurons to different locations. After birth, the inflowing stream of sights, sounds, smells, touches, language, and eye contact helps to shape the brain’s neural connections, as does stimulation from caregivers and others. The neuroconstructivist view, in which brain development is influenced by a person’s environment and experiences, is an increasingly popular perspective.
- Newborns usually sleep about 18 hours a day. By 6 months of age, many American infants approach adult-like sleeping patterns. REM sleep—during which dreaming occurs—is present more in early infancy than in childhood and adulthood.
- Sleeping arrangements for infants vary across cultures. In America, infants are more likely to sleep alone than in many other cultures. Some experts believe shared sleeping can lead to sudden infant death syndrome (SIDS), a condition that occurs when a sleeping infant suddenly stops breathing and dies without an apparent cause. However, it is generally accepted that the most critical factor in predicting whether an infant will develop SIDS is prone sleeping.
- Infants need to consume about 50 calories per day for each pound they weigh. The growing consensus is that in most instances breast feeding is superior to bottle feeding for both the infant and the mother, although the correlational nature of studies must be considered.
- Severe infant malnutrition is still prevalent in manyPage 136 parts of the world. A special concern in impoverished countries is early weaning from breast milk and the misuse and hygiene problems associated with bottle feeding in these countries. The Women, Infants, and Children (WIC) program has produced positive benefits in low-income families in the United States.
2 Motor Development
LG2 Describe infants’ motor development.
The Dynamic Systems View
Reflexes
Gross Motor Skills
Fine Motor Skills
- Thelen’s dynamic systems theory seeks to explain how motor behaviors are assembled for perceiving and acting. Perception and action are coupled. According to this theory, motor skills are the result of many converging factors, such as the development of the nervous system, the body’s physical properties and its movement possibilities, the goal the child is motivated to reach, and environmental support for the skill. In the dynamic systems view, motor development is far more complex than the result of a genetic blueprint.
- Reflexes—automatic movements—govern the newborn’s behavior. They include the sucking, rooting, and Moro reflexes. The rooting and Moro reflexes disappear after three to four months. Permanent reflexes include coughing and blinking. For infants, sucking is an especially important reflex because it provides a means of obtaining nutrition.
- Gross motor skills involve large-muscle activities. Key skills developed during infancy include control of posture and walking. Although infants usually learn to walk by their first birthday, the neural pathways that allow walking begin forming earlier. The age at which infants reach milestones in the development of gross motor skills may vary by as much as two to four months, especially for milestones in late infancy.
- Fine motor skills involve finely tuned movements. The onset of reaching and grasping marks a significant accomplishment, and this skill becomes more refined during the first two years of life.
3 Sensory and Perceptual Development
LG3 Summarize the course of sensory and perceptual development in infancy.
What Are Sensation and Perception?
The Ecological View
Visual Perception
Other Senses
Intermodal Perception
Nature, Nurture, and Perceptual Development
Perceptual-Motor Coupling
- Sensation occurs when information interacts with sensory receptors. Perception is the interpretation of sensation.
- Created by the Gibsons, the ecological view states that we directly perceive information that exists in the world around us. Perception brings people in contact with the environment to interact with and adapt to it. Affordances provide opportunities for interaction offered by objects that fit within our capabilities to perform activities.
- Researchers have developed a number of methods to assess the infant’s perception, including the visual preference method (which Fantz used to determine young infants’ preference for looking at patterned over nonpatterned displays), habituation and dishabituation, and tracking.
- The infant’s visual acuity increases dramatically in the first year of life. Infants’ color vision improves as they develop. Young infants systematically scan human faces. As early as 3 months of age, infants show size and shape constancy. At approximately 2 months of age, infants develop the ability to perceive that occluded objects are complete. In Gibson and Walk’s classic study, infants as young as 6 months of age indicated they could perceive depth.
- The fetus can hear during the last two months of pregnancy. Immediately after birth, newborns can hear, but their sensory threshold is higher than that of adults. Developmental changes in the perception of loudness, pitch, and localization of sound occur during infancy. Newborns can respond to touch and feel pain. Newborns can differentiate odors, and sensitivity to taste may be present before birth.
- Early, exploratory forms of intermodal perception—the ability to relate and integrate information from two or more sensory modalities—are present in newborns and become sharper over the first year of life.
- In describing the sources of perceptualPage 137 development, nature advocates are referred to as nativists and nurture proponents are called empiricists. The Gibsons’ ecological view that has guided much of perceptual development research leans toward a nativist approach but still allows for developmental changes in distinctive features. Piaget’s constructivist view leans toward an empiricist approach, emphasizing that many perceptual accomplishments must await the development of cognitive stages in infancy. A strong empiricist approach is unwarranted. A full account of perceptual development includes the roles of nature, nurture, and the developing sensitivity to information.
- Perception and action are often not isolated but rather are coupled. Individuals perceive in order to move and move in order to perceive.
key terms
sudden infant death syndrome (SIDS)
key people
Karen Adolph
Martha Ann Bell
Robert Fantz
Eleanor Gibson
James J. Gibson
William James
Mark Johnson
Scott Johnson
Rachel Keen
Patricia Kuhl
Daphne Maurer
Charles Nelson
John Richards
Esther Thelen
Richard Walk
chapter 5
COGNITIVE DEVELOPMENT IN INFANCY
chapter outline
1 Piaget’s Theory of Infant Development
Learning Goal 1 Summarize and evaluate Piaget’s theory of infant development.
Evaluating Piaget’s Sensorimotor Stage
2 Learning, Attention, Remembering, and Conceptualizing
Learning Goal 2 Describe how infants learn, focus attention, remember, and conceptualize.
Concept Formation and Categorization
Learning Goal 3 Describe the nature of language and how it develops in infancy.
Biological and Environmental Influences
©DreamPictures/Getty Images
Jean Piaget, the famous Swiss Page 139psychologist, was a meticulous observer of his three children—Laurent, Lucienne, and Jacqueline. His books on cognitive development are filled with these observations. Here are a few of Piaget’s observations of his children in infancy (Piaget, 1952):
- At 21 days of age, “Laurent found his thumb after three attempts: prolonged sucking begins each time. But, once he has been placed on his back, he does not know how to coordinate the movement of the arms with that of the mouth and his hands draw back even when his lips are seeking them” (p. 27).
- During the third month, thumb sucking becomes less important to Laurent because of new visual and auditory interests. But, when he cries, his thumb goes to the rescue.
- Toward the end of Lucienne’s fourth month, while she is lying in her crib, Piaget hangs a doll above her feet. Lucienne thrusts her feet at the doll and makes it move. “Afterward, she looks at her motionless foot for a second, then recommences. There is no visual control of her foot, for the movements are the same when Lucienne only looks at the doll or when I place the doll over her head. On the other hand, the tactile control of the foot is apparent: after the first shakes, Lucienne makes slow foot movements as though to grasp and explore” (p. 159).
- At 11 months, “Jacqueline is seated and shakes a little bell. She then pauses abruptly in order to delicately place the bell in front of her right foot; then she kicks hard. Unable to recapture it, she grasps a ball which she then places at the same spot in order to give it another kick” (p. 225).
- At 1 year, 2 months, “Jacqueline holds in her hands an object which is new to her: a round, flat box which she turns all over, shakes, [and] rubs against the bassinet. . . . She lets it go and tries to pick it up. But she only succeeds in touching it with her index finger, without grasping it. She nevertheless makes an attempt and presses on the edge. The box then tilts up and falls again” (p. 273). Jacqueline shows an interest in this result and studies the fallen box.
For Piaget, these observations reflect important changes in the infant’s cognitive development. Piaget maintained that infants go through a series of cognitive substages as they progress in less than two short years.
Page 140
topical connections looking back
We have discussed that impressive advances occur in the development of the brain during infancy. Engaging in various physical, cognitive, and socioemotional activities strengthens the baby’s neural connections. Motor and perceptual development also are key aspects of the infant’s development. An important part of this development is the coupling of perceptions and actions. The nature-nurture issue continues to be debated with regard to the infant’s perceptual development. In this chapter, you will expand your understanding of the infant’s brain, motor, and perceptual development by further examining how infants develop their competencies, focusing on how advances in their cognitive development help them adapt to their world, and how the nature-nurture issue is a key aspect of the infant’s cognitive and language development.
preview
Piaget’s descriptions of infants are just the starting point for our exploration of cognitive development. Excitement and enthusiasm about the study of infant cognition have been fueled by an interest in what newborns and infants know, by continued fascination about innate and learned factors in the infant’s cognitive development, and by controversies about whether infants construct their knowledge (Piaget’s view) or know their world more directly. In this chapter, you will not only study Piaget’s theory of infant development but also explore how infants learn, remember, and conceptualize; learn about some of their individual differences; and trace their language development.
1 Piaget’s Theory of Infant Development
LG1 Summarize and evaluate Piaget’s theory of
infant development.
Cognitive Processes
The Sensorimotor Stage
Evaluating Piaget’s Sensorimotor Stage
Poet Nora Perry asks, “Who knows the thoughts of a child?” As much as anyone, Piaget knew. Through careful observations of his own three children—Laurent, Lucienne, and Jacqueline—and observations of and interviews with other children, Piaget changed perceptions of the way children think about the world.
We are born capable of learning.
—Jean-Jacques Rousseau
Swiss-born French Philosopher, 18th Century
Piaget’s theory is a general, unifying story of how biology and experience sculpt cognitive development. Piaget thought that, just as our physical bodies have structures that enable us to adapt to the world, we build mental structures that help us adjust to new environmental demands. Piaget stressed that children actively construct their own cognitive worlds; information is not just poured into their minds from the environment. He sought to discover how children at different points in their development think about the world and how systematic changes in their thinking occur.
COGNITIVE PROCESSES
What processes do children use as they construct their knowledge of the world? Piaget developed several concepts to answer this question; especially important are schemes, assimilation, accommodation, organization, equilibrium, and equilibration.
Schemes As the infant or child seeks to construct an understanding of the world, said Piaget (1954), the developing brain creates schemes. These are actions or mental representations that organize knowledge. In Piaget’s theory, a baby’s schemes are structured by simple actions that can be performed on objects, such as sucking, looking, and grasping. Older children have schemes that include strategies and plans for solving problems. For example, in the descriptions at the opening of this chapter, Laurent Page 141displayed a scheme for sucking. By the time we have reached adulthood, we have constructed an enormous number of diverse schemes, ranging from driving a car to balancing a budget to understanding the concept of fairness.
Assimilation and Accommodation To explain how children use and adapt their schemes, Piaget offered two concepts: assimilation and accommodation. Assimilation occurs when children use their existing schemes to deal with new information or experiences. Accommodation occurs when children adjust their schemes to take new information and experiences into account.
Think about a toddler who has learned the word car to identify the family vehicle. The toddler might call all moving vehicles on roads “cars,” including motorcycles and trucks; the child has assimilated these objects to his or her existing scheme. But the child soon learns that motorcycles and trucks are not cars and fine-tunes the category to exclude motorcycles and trucks, accommodating the scheme.
Assimilation and accommodation operate even in very young infants. Newborns reflexively suck everything that touches their lips; they assimilate all sorts of objects into their sucking scheme. By sucking different objects, they learn about their taste, texture, shape, and so on. After several months of experience, though, they construct their understanding of the world differently. Some objects, such as fingers and the mother’s breast, can be sucked, and others, such as fuzzy blankets, should not be sucked. In other words, they accommodate their sucking scheme.
In Piaget’s view, what is a scheme? What schemes might this young infant be displaying?
©Maya Kovacheva Photography/Getty Images
Organization To make sense out of their world, said Piaget, children cognitively organize their experiences. Organization in Piaget’s theory is the grouping of isolated behaviors and thoughts into a higher-order system. Continual refinement of this organization is an inherent part of development. A boy who has only a vague idea about how to use a hammer may also have a vague idea about how to use other tools. After learning how to use each one, he relates these uses, organizing his knowledge.
Equilibration and Stages of Development Assimilation and accommodation always take the child to a higher ground, according to Piaget. In trying to understand the world, the child inevitably experiences cognitive conflict, or disequilibrium. That is, the child is constantly faced with counterexamples to his or her existing schemes and with inconsistencies. For example, if a child believes that pouring water from a short and wide container into a tall and narrow container changes the amount of water, then the child might be puzzled by where the “extra” water came from and whether there is actually more water to drink. The puzzle creates disequilibrium; for Piaget, an internal search for equilibrium creates motivation for change. The child assimilates and accommodates, adjusting old schemes, developing new schemes, and organizing and reorganizing the old and new schemes. Eventually, the new organization has become fundamentally different from the old organization; it is a new way of thinking.
developmental connection
Cognitive Theory
Recall the main characteristics of Piaget’s four stages of cognitive development. Connect to “Introduction.”
In short, according to Piaget, children constantly assimilate and accommodate as they seek equilibrium. There is considerable movement between states of cognitive equilibrium and disequilibrium as assimilation and accommodation work in concert to produce cognitive change. Equilibration is the name Piaget gave to this mechanism by which children shift from one stage of thought to the next.
The result of these processes, according to Piaget, is that individuals go through four stages of development. A different way of understanding the world makes one stage more advanced than another. Cognition is qualitatively different in one stage compared with another. In other words, the way children reason at one stage is different from the way they reason at another stage. In this chapter we will focus on Piaget’s stage of infant cognitive development. In later chapters we will explore Piaget’s other three stages when we study cognitive development in early childhood, middle and late childhood, and adolescence.
THE SENSORIMOTOR STAGE
The sensorimotor stage lasts from birth to about 2 years of age. During this stage of cognitive development, infants construct an understanding of the world by coordinating sensory experiences (such as seeing and hearing) with physical, motoric actions—hence the term “sensorimotor.” At the beginning of this stage, Page 142newborns have little more than reflexes with which to work. At the end of the sensorimotor stage, 2-year-olds can produce complex sensorimotor patterns and use primitive symbols. We first will summarize Piaget’s descriptions of how infants develop. Later we will consider criticisms of his view.
Substages Piaget divided the sensorimotor stage into six substages: (1) simple reflexes; (2) first habits and primary circular reactions; (3) secondary circular reactions; (4) coordination of secondary circular reactions; (5) tertiary circular reactions, novelty, and curiosity; and (6) internalization of schemes (see Figure 1). Piaget argued that each substage builds on the previous one.
FIGURE 1 PIAGET’S SIX SUBSTAGES OF SENSORIMOTOR DEVELOPMENT
Simple reflexes, the first sensorimotor substage, corresponds to the first month after birth. In this substage, sensation and action are coordinated primarily through reflexive behaviors such as rooting and sucking. Soon the infant produces behaviors that resemble reflexes in the absence of the usual stimulus for the reflex. For example, a newborn will suck a nipple or bottle only when it is placed directly in the baby’s mouth or touched to the lips. But soon the infant might suck when a bottle or nipple is only nearby. Even in the first month of life, the infant is initiating action and actively structuring experiences.
First habits and primary circular reactions is the second sensorimotor substage, which develops between 1 and 4 months of age. In this substage, the infant coordinates sensation and two types of schemes: habits and primary circular reactions. A habit is a scheme based on a reflex that has become completely separated from its eliciting stimulus. For example, infants in substage 1 suck when bottles are put to their lips or when they see a bottle. Infants in substage 2 might suck even when no bottle is present. A circular reaction is a repetitive action.
A primary circular reaction is a scheme based on the attempt to reproduce an event that initially occurred by chance. For example, suppose an infant accidentally sucks his fingers when they are placed near his mouth. Later, he searches for his fingers to suck them again, but the fingers do not cooperate because the infant cannot coordinate visual and manual actions.
Habits and circular reactions are stereotyped—that is, the infant repeats them the same way each time. During this substage, the infant’s own body continues to be the center of attention. There is no outward pull by environmental events.
Secondary circular reactions Page 143is the third sensorimotor substage, which develops between 4 and 8 months of age. In this substage, the infant becomes more object-oriented, moving beyond preoccupation with the self. The infant’s schemes are not intentional or goal-directed, but they are repeated because of their consequences. By chance, an infant might shake a rattle. The infant repeats this action for the sake of its fascination. This is a secondary circular reaction: an action repeated because of its consequences. The infant also imitates some simple actions, such as the baby talk or burbling of adults, and some physical gestures. However, the baby imitates only actions that he or she is already able to produce.
This 7-month-old is in Piaget’s substage of secondary circular reactions. What might the infant do that suggests he is in this substage?
©Johnny Valley/Getty ImagesThis 17-month-old is in Piaget’s stage of tertiary circular reactions. What might the infant do that suggests he is in this stage?
©Punchstock/Corbis
Coordination of secondary circular reactions is Piaget’s fourth sensorimotor substage, which develops between 8 and 12 months of age. To progress into this substage the infant must coordinate vision and touch, eye and hand. Actions become more outwardly directed. Significant changes during this substage involve the coordination of schemes and intentionality. Infants readily combine and recombine previously learned schemes in a coordinated way. They might look at an object and grasp it simultaneously, or they might visually inspect a toy, such as a rattle, and finger it simultaneously, exploring it tactilely. Actions are even more outwardly directed than before. Related to this coordination is the second achievement—the presence of intentionality. For example, infants might manipulate a stick in order to bring a desired toy within reach, or they might knock over one block to reach and play with another one. Similarly, when 11-month-old Jacqueline, as described in the chapter opening, placed the ball in front of her and kicked it, she was demonstrating intentionality.
developmental connection
Cognitive Theory
What are some changes in symbolic thought in young children? Connect to “Physical and Cognitive Development in Early Childhood.”
Tertiary circular reactions, novelty, and curiosity is Piaget’s fifth sensorimotor substage, which develops between 12 and 18 months of age. In this substage, infants become intrigued by the many properties of objects and by the many things that they can make happen to objects. A block can be made to fall, spin, hit another object, and slide across the ground. Tertiary circular reactions are schemes in which the infant purposely explores new possibilities with objects, continually doing new things to them and exploring the results. Piaget says that this stage marks the starting point for human curiosity and interest in novelty.
Internalization of schemes is Piaget’s sixth and final sensorimotor substage, which develops between 18 and 24 months of age. In this substage, the infant develops the ability to use primitive symbols. For Piaget, a symbol is an internalized sensory image or word that represents an event. Primitive symbols permit the infant to think about concrete events without directly acting them out or perceiving them. Moreover, symbols allow the infant to manipulate and transform the represented events in simple ways. In a favorite Piagetian example, Piaget’s young daughter saw a matchbox being opened and closed. Later, she mimicked the event by opening and closing her mouth. This was an obvious expression of her image of the event.
Object Permanence Imagine how chaotic and unpredictable your life would be if you could not distinguish between yourself and your world. This is what the life of a newborn must be like, according to Piaget. There is no differentiation between the self and world; objects have no separate, permanent existence.
By the end of the sensorimotor period, objects are both separate from the self and permanent. Object permanence is the understanding that objects continue to exist even when they cannot be seen, heard, or touched. Acquiring the sense of object permanence is one of the infant’s most important accomplishments, according to Piaget.
How could anyone know whether Page 144an infant had a sense of object permanence or not? The principal way that object permanence is studied is by watching an infant’s reaction when an interesting object disappears (see Figure 2). If infants search for the object, it is assumed that they believe it continues to exist.
FIGURE 2 OBJECT PERMANENCE. Piaget argued that object permanence is one of infancy’s landmark cognitive accomplishments. For this 5-month-old boy, “out of sight” is literally out of mind. The infant looks at the toy monkey (left), but, when his view of the toy is blocked (right), he does not search for it. Several months later, he will search for the hidden toy monkey, an action reflecting the presence of object permanence.
©Doug Goodman/Science Source
EVALUATING PIAGET’S SENSORIMOTOR STAGE
Piaget opened up a new way of looking at infants with his view that their main task is to coordinate their sensory impressions with their motor activity. However, the infant’s cognitive world is not as neatly packaged as Piaget portrayed it, and some of Piaget’s explanations of change are debated. In the past several decades, sophisticated experimental techniques have been devised to study infants, and a large number of research studies have focused on infant development. Much of the new research suggests that Piaget’s view of sensorimotor development needs to be modified (Adolph, 2018; Bell & others, 2018; Bremner & others, 2017;
Van de Vondervoort & Hamlin, 2018).
The A-not-B Error One modification concerns Piaget’s claim that certain processes are crucial in transitions from one stage to the next. The data do not always support his explanations. For example, in Piaget’s theory, an important feature in the progression into substage 4, coordination of secondary circular reactions, is an infant’s inclination to search for a hidden object in a familiar location rather than to look for the object in a new location. If a toy is hidden twice, initially at location A and subsequently at location B, 8- to 12-month-old infants search correctly at location A initially. But, when the toy is subsequently hidden at location B, while the child watches, they make the mistake of continuing to search for it at location A. A-not-B error is the term used to describe this common mistake. Older infants are less likely to make the A-not-B error because their concept of object permanence is more complete.
Researchers have found, however, that the A-not-B error does not show up consistently (MacNeill & others, 2018; Sophian, 1985). The evidence indicates that A-not-B errors are sensitive to the delay between hiding the object at B and the infant’s attempt to find it (Diamond, 1985). Thus, the A-not-B error might be due to a failure in memory. And A-not-B performance may be linked to attention as well. For example, in a recent study, 5-month-olds’ more focused attention on a separate task involving a puppet was linked to better performance on an A-not-B task that involved locating an object after it was hidden from view (Marcovitch & others, 2016). Another explanation is that infants tend to repeat a previous motor behavior (Clearfield & others, 2006).
developmental connection
Perceptual Development
Eleanor Gibson was a pioneer in crafting the ecological perception view of development. Connect to “Physical Development in Infancy.”
Perceptual Development and Expectations A number of theorists, such as Eleanor Gibson (2001) and Elizabeth Spelke (1991, 2011, 2013), argue that infants’ perceptual abilities are highly developed at a very early stage. Spelke concludes that young infants interpret the world as having predictable occurrences. For example, we have discussed research that demonstrated the presence of intermodal perception—the ability to coordinate information from two or more sensory modalities, such as vision and hearing—by 3½ months of age, much earlier Page 145than Piaget would have predicted (Spelke & Owsley, 1979).
Research also suggests that infants develop the ability to understand how the world works at a very early age (Aslin, 2017; Baillargeon & DeJong, 2017; Liu & Spelke, 2017; Van de Vondervoort & Hamlin, 2018). For example, by the time they are 3 months of age, infants develop expectations about future events. What kinds of expectations do infants form? Experiments by Elizabeth Spelke (Liu & Spelke, 2017; Spelke, 1991, 2000, 2016a, b) have addressed this question. In one study, she placed babies before a puppet stage and showed them a series of actions that are unexpected if you know how the physical world works—for example, one ball seemed to roll through a solid barrier, another seemed to leap between two platforms, and a third appeared to hang in midair (Spelke, 1979). Spelke measured and compared the babies’ looking times for unexpected and expected actions. She concluded that by 4 months of age, even though infants do not yet have the ability to talk about objects, move around objects, manipulate objects, or even see objects with high resolution, they expect objects to be solid and continuous. However, at 4 months of age, infants do not expect an object to obey laws of gravity (Spelke & others, 1992). Similarly, research by Renee Baillargeon and her colleagues (Baillargeon, 1995, 2004, 2014, 2016) documents that infants as young as 3 to 4 months expect objects to be substantial (in the sense that other objects cannot move through them) and permanent (in the sense that objects continue to exist when they are hidden).
In sum, researchers conclude that infants see objects as bounded, unitary, solid, and separate from their background, possibly at birth or shortly thereafter, but definitely by 3 to 4 months of age—much earlier than Piaget envisioned. Young infants still have much to learn about objects, but the world appears both stable and orderly to them (Bremner, 2017; Liu & Spelke, 2017; Stavans & Baillargeon, 2018).
By 6 to 8 months, infants have learned to perceive gravity and support—that an object hanging on the end of a table should fall, that ball bearings will travel farther when rolled down a longer rather than a shorter ramp, and that cup handles will not fall when attached to a cup (Slater, Field, & Hernandez-Reif, 2007). As infants develop, their experiences and actions on objects help them to understand physical laws (Baillargeon & DeJong, 2017; Bremner, 2017).
The Nature-Nurture Issue In considering the big issue of whether nature or nurture plays the more important role in infant development, Elizabeth Spelke (Spelke, 2003, 2011, 2013, 2016a, b) comes down clearly on the side of nature, a position often referred to as nativist. Spelke endorses a core knowledge approach, which states that infants are born with domain-specific innate knowledge systems. Among these domain-specific knowledge systems are those involving space, number sense, object permanence, and language (which we will discuss later in this chapter). Strongly influenced by evolution, the core knowledge domains are theorized to be prewired to allow infants to make sense of their world (Strickland & Chemla, 2018). After all, Spelke concludes, how could infants possibly grasp the complex world in which they live if they didn’t come into the world equipped with core sets of knowledge? In this approach, the innate core knowledge domains form a foundation around which more mature cognitive functioning and learning develop (Baillargeon & DeJong, 2017). The core knowledge approach argues that Piaget greatly underestimated the cognitive abilities of infants, especially young infants (Baillargeon, 2016; Liu & Spelke, 2017; Spelke, 2016a, b).
developmental connection
Nature Versus Nurture
The nature-nurture debate is one of developmental psychology’s main issues. Connect to “Introduction” and “Biological Beginnings.”
Some critics argue that the Spelke experiments mainly demonstrate perceptual competencies or detection of regularities in the environment (Heyes, 2014; Ruffman, 2014). These critics stress that the infants in their studies reflect a very rudimentary understanding that likely differs greatly from the understanding of older children.
An intriguing domain of core knowledge that has been investigated in young infants is whether they have a sense of number. Spelke (2016a, b) concludes that they do (Spelke, 2016a, b). She has found that infants can distinguish between different numbers of objects, actions, and sounds (Spelke, 2016a, b). Of course, not everyone agrees with Spelke’s conclusions about young infants’ math skills (Cohen, 2002). One criticism is that infants in the number experiments are merely responding to changes in the display that violated their expectations.
Recently, researchers also have explored whether Page 146preverbal infants might have a built-in, innate sense of morality (Van de Vondervoort & Hamlin, 2016, 2018). In this research, infants as young as 4 months of age are more likely to make visually guided reaches toward a puppet who has acted as a helper (such as helping someone get up a hill, assisting in opening a box, or giving a ball back) rather than toward a puppet who has acted as a hinderer to others’ efforts to achieve such goals (Hamlin, 2013, 2014). Recently, the view that the emergence of morality in infancy is innate was described as problematic (Carpendale & Hammond, 2016). Instead it was argued that morality may emerge through infants’ early interaction with others and later transformation through language and reflective thought.
What are some conclusions that can be reached about infant learning and cognition?
©baobao ou/Getty Images
In criticizing the core knowledge approach, British developmental psychologist Mark Johnson (2008) says that the infants studied by Spelke and other advocates of core knowledge already have accumulated hundreds, and in some cases even thousands, of hours of experience in grasping what the world is about, which gives considerable room for the environment’s role in the development of infant cognition (Highfield, 2008). According to Johnson (2008), infants likely come into the world with “soft biases to perceive and attend to different aspects of the environment, and to learn about the world in particular ways.” A major criticism is that nativists completely neglect the infant’s social immersion in the world and instead focus only on what happens inside the infant’s head, apart from the environment (de Haan & Johnson, 2016; Hakuno & others, 2018).
Although debate about the cause and course of infant cognitive development continues, most developmentalists today agree that Piaget underestimated the early cognitive accomplishments of infants and that both nature and nurture are involved in infants’ cognitive development (Bell & others, 2018; Bremner & others, 2017; Gomez, 2017).
Conclusions In sum, many researchers conclude that Piaget wasn’t specific enough about how infants learn about their world and that infants, especially young infants, are more competent than Piaget thought (Adolph, 2018; Aslin, 2017; Baillargeon & De Jong, 2017; Bell & others, 2018; Bremner & others, 2017). As researchers have examined the specific ways that infants learn, the field of infant cognition has become very specialized. There are many researchers working on different questions, with no general theory emerging that can connect all of the different findings (Nelson, 1999). These theories often are local theories, focused on specific research questions, rather than grand theories like Piaget’s (Kuhn, 1998). Among the unifying themes in the study of infant cognition are seeking to understand more precisely how developmental changes in cognition take place, to examine the big issue of nature and nurture, and to study the brain’s role in cognitive development (Aslin, 2017; Bauer, 2015a, b, 2018; Bell & others, 2018; Van de Vondervoort & Hamlin, 2018; Xie, Mallin, & Richards, 2018). Recall that exploring connections between brain, cognition, and development involves the recently emerging field of developmental cognitive neuroscience (Bick & Nelson, 2018; Meltzoff & others, 2018a, b; Saez de Urabain, Nuthmann, & Johnson, 2017).
Review Connect Reflect
LG1 Summarize and evaluate Piaget’s theory of infant development.
Review
- What cognitive processes are important in Piaget’s theory?
- What are some characteristics of Piaget’s stage of sensorimotor development?
- What are some contributions and criticisms of Piaget’s sensorimotor stage?
Connect
- You just read that by the age of
6 to 8 months infants have learned to perceive gravity and support. What physical developments occurring around this same time period might contribute to infants’ exploration and understanding of these concepts?
Reflect Your Own Personal Journey of Life
- What are some implications of Piaget’s theory for parenting your own baby?
Page 147
2 Learning, Attention, Remembering, and Conceptualizing
LG2 Describe how infants learn, focus attention, remember, and conceptualize.
Conditioning
Attention
Memory
Imitation
Concept Formation and Categorization
When Piaget hung a doll above 4-month-old Lucienne’s feet, as described in the chapter opening, did she remember the doll? If Piaget had rewarded her for moving the doll with her foot, would that have affected Lucienne’s behavior? If he had shown her how to shake the doll’s hand, could she have imitated him? If he had shown her a different doll, could she have formed the concept of a “doll”?
Questions like these might be examined by researchers taking the behavioral and social cognitive or information-processing approaches introduced earlier. In contrast with Piaget’s theory, these approaches do not describe infant development in terms of stages. Instead, they document gradual changes in the infant’s ability to understand and process information about the world (Hakuno & others, 2018; Reynolds & Richards, 2018). In this section, we explore what researchers using these approaches can tell us about how infants learn, remember, and conceptualize.
developmental connection
Theories
The behavioral and social cognitive approaches emphasize continuity rather than discontinuity in development. Connect to “Introduction.”
CONDITIONING
According to Skinner’s theory of operant conditioning, the consequences of a behavior produce changes in the probability of the behavior’s occurrence. For example, if an infant’s behavior is followed by a rewarding stimulus, the behavior is likely to recur.
Operant conditioning has been especially helpful to researchers in their efforts to determine what infants perceive (Rovee-Collier & Barr, 2010). For example, infants will suck faster on a nipple when the sucking behavior is followed by a visual display, music, or a human voice (Rovee-Collier, 1987, 2009).
Carolyn Rovee-Collier (1987) has also demonstrated how infants can retain information from the experience of being conditioned. In a characteristic experiment, she places a 2½-month-old baby in a crib under an elaborate mobile (see Figure 3). She then ties one end of a ribbon to the baby’s ankle and the other end to the mobile. Subsequently, she observes that the baby kicks and makes the mobile move. The movement of the mobile is the reinforcing stimulus (which increases the baby’s kicking behavior) in this experiment. Weeks later, the baby is returned to the crib, but its foot is not tied to the mobile. The baby kicks, which suggests it has retained the information that if it kicks a leg, the mobile will move.
FIGURE 3 THE TECHNIQUE USED IN ROVEE-COLLIER’S INVESTIGATION OF INFANT MEMORY. In Rovee-Collier’s experiment, operant conditioning was used to demonstrate that infants as young as 2½ months of age can retain information from the experience of being conditioned. What did infants recall in Rovee-Collier’s experiment?
Courtesy of Dr. Carolyn Rovee-Collier
ATTENTION
Attention, the focusing of mental resources on select information, improves cognitive processing on many tasks (Posner, 2018a, b; Wu & Scerif, 2018; Yu & Smith, 2017). At any one time, though, people can pay attention to only a limited amount of information. Even newborns can detect a contour and fix their attention on it. Older infants scan patterns more thoroughly. By 4 months, infants can selectively attend to an object.
In adults, when individuals orient their attention to an object or event, the parietal lobes in the cerebral cortex are involved (Kulke, Atkinson, & Braddick, 2017). It is likely that the parietal lobes are active when infants orient their attention, although research has not yet documented this. (Figure 5 in the chapter on “Physical Development in Infancy” illustrates the location of the parietal lobes in the brain.)
developmental connection
Attention
In early childhood, children make significant advances in sustained attention. Connect to “Physical and Cognitive Development in Early Childhood.”
Attention in the first year of life is dominated by an orienting/investigative process (Falck-Ytter & others, 2018). This process involves directing attention to potentially important locations in the environment (that is, where) and recognizing objects and their features (such as color and form) (that is, what). From 3 to 9 months of age, infants can deploy their attention more flexibly and quickly. Another important type of attention is sustained attention, also referred to as focused attention (Ito-Jager & others, 2017; Xie, Mallin, & Richards, 2018). New stimuli typically elicit an orienting response followed by sustained attention. It is sustained attention that allows infants to learn about and remember characteristics of a stimulus as it becomes familiar. Researchers have Page 148found that infants as young as 3 months of age engage in 5 to 10 seconds of sustained attention. From this age through the second year, the length of sustained attention increases (Courage & Richards, 2008). In a recent study, sustained attention at 10 months of age was linked to better self-regulation at 18 months of age, even when infants had insensitive mothers (Frick & others, 2018).
Habituation and Dishabituation Closely linked with attention are the processes of habituation and dishabituation (Christodoulou, Leland, & Moore, 2018; Jones & others, 2017). If you say the same word or show the same toy to a baby several times in a row, the baby usually pays less attention to it each time. This is habituation—decreased responsiveness to a stimulus after repeated presentations of the stimulus. Dishabituation is the increase in responsiveness after a change in stimulation. The chapter on “Physical Development in Infancy” described some of the measures that researchers use to study whether habituation is occurring, such as sucking behavior, heart rate, and the length of time the infant looks at an object.
This young infant’s attention is riveted on the yellow toy duck that has just been placed in front of him. The young infant’s attention to the toy will be strongly regulated by the processes of habituation and dishabituation. What characterizes these processes?
©Sporrer/Rupp/Getty Images
Infants’ attention is strongly governed by novelty and habituation (Messinger & others, 2017). When an object becomes familiar, attention becomes shorter, and infants become more vulnerable to distraction.
Habituation provides a useful tool for assessing what infants can see, hear, smell, taste, and experience touch. When infants habituate to one object, and thus it becomes familiar, they will then tend to look at an unfamiliar object, which shows they can tell the objects apart.
Knowing about habituation and dishabituation can help parents interact effectively with infants. Infants respond to changes in stimulation. Wise parents sense when an infant shows an interest and realize that they may have to repeat something many times for the infant to process information. But if the stimulation is repeated often, the infant stops responding to the parent. In parent-infant interaction, it is important for parents to do novel things and to repeat them often until the infant stops responding. The parent stops or changes behaviors when the infant redirects his or her attention (Rosenblith, 1992).
Joint Attention Another type of attention that is an important aspect of infant development is joint attention, in which two or more individuals focus on the same object or event (Mateus & others, 2018; Urqueta Alfaro & others, 2018). Joint attention requires (1) an ability to track another’s behavior, such as following the gaze of another person; (2) one person’s directing another’s attention; and (3) reciprocal interaction. Early in infancy, joint attention involves a caregiver pointing, turning the infant’s head, snapping fingers, or using words to direct the infant’s attention. Emerging forms of joint attention occur at about 7 to 8 months, but it is not until toward the end of the first year that joint attention skills are frequently observed (Niedzwiecka & Tomalski, 2015). In a study conducted by Andrew Meltzoff and Rechele Brooks (2006), at 10 to 11 months of age infants first began engaging in “gaze following,” looking where another person has just looked (see Figure 4). And by their first birthday, infants have begun to Page 149direct adults’ attention to objects that capture their interest (Heimann & others, 2006). One study found that problems in joint attention as early as 8 months of age were linked to the child being diagnosed with autism by 7 years of age (Veness & others, 2014). Also, a recent study involving the use of eye-tracking equipment with 11- to 24-month-olds revealed that infants’ hand-eye coordination rather than gaze following alone predicted joint attention (Yu & Smith, 2017).
FIGURE 4 GAZE FOLLOWING IN INFANCY. Researcher Rechele Brooks shifts her eyes from the infant to a toy in the foreground (a). The infant then follows her eye movement to the toy (b). Brooks and colleague Andrew Meltzoff (2005) found that infants begin to engage in this kind of behavior, called “gaze following,” at 10 to 11 months of age. Why might gaze following be an important accomplishment for an infant?
©2005 University of Washington, Institute for Learning & Brain Sciences
Joint attention plays important roles in many aspects of infant development and considerably increases infants’ ability to learn from other people (McClure & others, 2018). Nowhere is this more apparent than in observations of interchanges between caregivers and infants as infants are learning language (Mason-Apps & others, 2018; Tomasello, 2014). When caregivers and infants frequently engage in joint attention, infants say their first word earlier and develop a larger vocabulary (Mastin & Vogt, 2016). Later in this chapter in our discussion of language, we further discuss joint attention as an early predictor of language development in older infants and toddlers (Mastin & Vogt, 2016). Researchers have found that joint attention is linked to better sustained attention (Yu & Smith, 2016), memory (Kopp & Lindenberger, 2011), self-regulation (Van Hecke & others, 2012), and executive function (Gueron-Sela & others, 2018).
A mother and her infant daughter engaging in joint attention. What about this photograph tells you that joint attention is occurring? Why is joint attention an important aspect of infant development?
©Tom Merton/Getty Images
MEMORY
Memory involves the retention of information over time. Attention plays an important role in memory as part of encoding, a process in which information is transferred to memory. What can infants remember, and when?
Some researchers, such as Carolyn Rovee-Collier (2009), have concluded that infants as young as 2 to 6 months of age can remember some experiences through 1½ to 2 years of age. However, critics such as Jean Mandler (2004), a leading expert on infant cognition, argue that the infants in Rovee-Collier’s experiments were displaying only implicit memory. Implicit memory refers to memory without conscious recollection—memories of skills and routine procedures that are performed automatically. In contrast, explicit memory refers to conscious remembering of facts and experiences.
When people think about memory, they are usually referring to explicit memory. Most researchers find that babies do not show explicit memory until the second half of the first year (Bauer, 2013, 2015a, b, 2018; Bauer & Fivush, 2014). Explicit memory improves substantially during the second year of life (Bauer, 2013, 2015a, b, 2018; Bauer & Leventon, 2015). In one longitudinal study, infants were assessed several times during their second year (Bauer & others, 2000). Older infants showed more accurate memory and required fewer prompts to demonstrate their memory than younger infants did. Figure 5 summarizes the lengths of time that infants of different ages can remember information (Bauer, 2009a, b). As indicated in Figure 5, researchers have documented that 6-month-olds can retain information for 24 hours, but by 20 months of age infants can remember information they encountered 12 months earlier.
FIGURE 5 AGE-RELATED CHANGES IN THE LENGTH OF TIME OVER WHICH MEMORY OCCURS
What changes in the brain are linked to infants’ memory development? From about 6 to 12 months of age, the maturation of the hippocampus and the surrounding cerebral cortex, especially the frontal lobes, makes explicit memory possible (see Figure 6). Explicit memory continues to improve during the second year as these brain structures further mature and connections between them increase. Less is known about the areas of the brain involved in implicit memory in infancy.
FIGURE 6 KEY BRAIN STRUCTURES INVOLVED IN EXPLICIT MEMORY DEVELOPMENT IN INFANCY
Let’s examine another aspect of memory. Do you remember your third birthday party? Probably not. Most adults can remember little if anything from their first three years of life. This is called infantile or childhood amnesia.
Patricia Bauer and her colleagues (Bauer, 2015a, 2018; Bauer & Larkina, 2014, 2016; Pathman, Doydum, & Bauer, 2013) have been recently studying when infantile amnesia begins to occur. In one study, children’s memory for events that occurred at 3 years of age was periodically assessed through age 9 (Bauer & Larkina, 2014). By 8 to 9 years of age, children’s memory of events that occurred at 3 years of age began to fade away significantly.
In Bauer’s (2015a, 2018) view, the processes that account for these developmental changes are early, gradual development of the ability to form, retain, and later retrieve memories of personally relevant past events followed by an accelerated rate of forgetting in childhood.
In sum, most of young infants’ conscious memories appear Page 150to be rather fragile and short-lived, although their implicit memory of perceptual-motor actions can be substantial (Bauer, 2015, 2018; Mandler, 2004). By the end of the second year, long-term memory is more substantial and reliable (Bauer, 2015a, b, 2018; Hayne & Gross, 2017).
IMITATION
Can infants imitate someone else’s emotional expressions? If an adult smiles, for example, will the baby respond with a smile? If an adult sticks out her tongue, wrinkles her forehead, and frowns, will the baby show a sad face?
Infant development researcher Andrew Meltzoff (2004, 2005, 2011; 2017; Meltzoff & Moore, 1999; Meltzoff & others, 2018a, b; Meltzoff & Williamson, 2010, 2013; Meltzoff, Williamson, & Marshall, 2013; Waismeyer & Meltzoff, 2017) has conducted numerous studies of infants’ imitative abilities. He sees infants’ imitative abilities as biologically based, because infants can imitate a facial expression within the first few days after birth. He also emphasizes that the infant’s imitative abilities do not resemble a hardwired response but rather involve flexibility and adaptability. Meltzoff (2017) also emphasizes that infants’ imitation informs us about their processing of social events and contributes to rapid social learning. In Meltzoff’s observations of infants throughout their first 72 hours of life, the infants gradually displayed more complete imitation of an adult’s facial expression, such as protruding the tongue or opening the mouth wide (see Figure 7).
FIGURE 7 INFANT IMITATION. Infant development researcher Andrew Meltzoff protrudes his tongue in an attempt to get the infant to imitate his behavior. How do Meltzoff’s findings about imitation compare with Piaget’s descriptions of infants’ abilities?
©Dr. Andrew Meltzoff
Meltzoff (2007) concludes that infants don’t blindly imitate everything they see and often make creative errors. He also argues that beginning at birth there is an interplay between learning by observing and learning by doing (Piaget emphasized learning by doing).
Meltzoff (2005, 2011, 2017) also has studied deferred imitation, which occurs after a time delay of hours or days. Piaget held that deferred imitation doesn’t occur until about 18 months of age. Meltzoff’s research suggested that it occurs much earlier. In one study, Meltzoff (1988) demonstrated that 9-month-old infants could imitate actions—such as pushing a recessed button in a box, which produced a beeping sound—that they had seen performed 24 hours earlier.
CONCEPT FORMATION AND CATEGORIZATION
Along with attention, memory, and imitation, concepts are key aspects of infants’ cognitive development (Quinn, 2016). Concepts are cognitive groupings of similar objects, events, people, or ideas. Without concepts, you would see each object and event as unique; you would not be able to make any generalizations.
Do infants have concepts? Yes, they do, although we do not know precisely how early concept formation begins (Quinn & Bhatt, 2016).
Using habituation experiments like those described earlier in the chapter, some researchers have found that infants as young as 3 to 4 months of age can group together objects with similar appearances, such as animals (Quinn, 2016). This research capitalizes on the knowledge that infants are more likely to look at a novel object than a familiar object. Jean Mandler (2004, 2009) argues that these early categorizations are best described as perceptual categorization. That is, the categorizations are based on similar perceptual features of objects, such as size, color, and movement, as well as parts of objects, such as legs for animals (Quinn & Bhatt, 2016). Mandler (2004) concludes that it is not until about 7 to 9 months of age that infants form conceptual categories rather than just making perceptual discriminations between different categories. In one study of 9- to 11-month-olds, infants classified birds as animals and airplanes as vehicles even Page 151though the objects were perceptually similar—airplanes and birds with their wings spread (Mandler & McDonough, 1993) (see Figure 8).
FIGURE 8 CATEGORIZATION IN 9- TO 11-MONTH-OLDS. These are the type of stimuli used in the study that indicated 9- to 11-month-old infants categorized birds as animals and airplanes as vehicles even though the objects were perceptually similar (Mandler & McDonough, 1993).
In addition to infants categorizing items on the basis of external, perceptual features such as shape, color, and parts, they also may categorize items on the basis of prototypes, or averages, that they extract from the structural regularities of items (Rakison & Lawson, 2013).
Infants are creating concepts and organizing their world into conceptual domains that will form the backbone of their thought throughout life.
—Jean Mandler
Contemporary Psychologist, University of
California–San Diego
Further advances in categorization occur in the second year of life (Booth, 2006; Rakison & Lawson, 2013). Many infants’ “first concepts are broad and global in nature, such as ‘animal’ or ‘indoor thing.’ Gradually, over the first two years these broad concepts become more differentiated into concepts such as ‘land animal,’ then ‘dog,’ or to ‘furniture,’ then ‘chair’” (Mandler, 2009, p. 1). Also in the second year, infants often categorize objects on the basis of their shape (Landau, Smith, & Jones, 1998).
Learning to put things into the correct categories—what makes something one kind of thing rather than another kind of thing, such as what makes a bird a bird, or a fish a fish—is an important aspect of learning (Quinn, 2016). As infant development researcher Alison Gopnik (2010, p. 159) pointed out, “If you can sort the world into the right categories—put things in the right boxes—then you’ve got a big advance on understanding the world.”
Do some very young children develop an intense, passionate interest in a particular category of objects or activities? One study confirmed that they do (DeLoache, Simcock, & Macari, 2007). A striking finding was the large gender difference in categories, with an intense interest in particular categories stronger for boys than girls. Categorization of boys’ intense interests focused on vehicles, trains, machines, dinosaurs, and balls; girls’ intense interests were more likely to involve dress-ups and books/reading (see Figure 9). When your author’s grandson Alex was 18 to 24 months old, he already had developed an intense, passionate interest in the category of vehicles. For example, at this age, he categorized vehicles into such subcategories as cars, trucks, earth-moving equipment, and buses. In addition to common classifications of cars into police cars, jeeps, taxis, and such, and trucks into fire trucks, dump trucks, and the like, his categorical knowledge of earth-moving equipment included bulldozers and excavators, and he categorized buses into school buses, London buses, and funky Malta buses (retro buses on the island of Malta). Later, at 3 years of age, Alex developed an intense, passionate interest in categorizing dinosaurs.
FIGURE 9 CATEGORIZATION OF BOYS’ AND GIRLS’ INTENSE INTERESTS
In sum, the infant’s advances in processing information—through attention, memory, imitation, and concept formation— Page 152is much richer, more gradual and less stage-like, and occurs earlier than was envisioned by earlier theorists, such as Piaget (Bauer, 2018; Bell & others, 2018; Bremner & others, 2017; Gomez, 2017; Xie, Mallin, & Richards, 2018). As leading infant researcher Jean Mandler (2004) concluded, “The human infant shows a remarkable degree of learning power and complexity in what is being learned and in the way it is represented” (p. 304).
I wish I could travel down by the road that crosses the baby’s mind where reason makes kites of her laws and flies them. . . .
—Rabindranath Tagore
Bengali Poet and Essayist, 20th Century
The author’s grandson Alex at 2 years of age showing his intense, passionate interest in the category of vehicles while playing with a London taxi and a funky Malta bus.
Courtesy of Dr. John Santrock
Review Connect Reflect
LG2 Describe how infants learn, remember, and conceptualize.
Review
- How do infants learn through conditioning?
- What is attention? What characterizes attention in infants?
- To what extent can infants remember?
- How is imitation involved in infant learning?
- When do infants develop concepts, and how does concept formation change during infancy?
Connect
- In this section, we learned that explicit memory improves in the second year as the hippocampus and frontal lobes mature and as connections between them increase. What did you learn in the text associated with Figure 6 in the chapter on “Physical Development in Infancy” that might also contribute to improvements in a mental process such as memory during this same time frame?
Reflect Your Own Personal Journey of Life
- If a friend told you that she remembers being abused by her parents when she was 2 years old, would you believe her? Explain your answer.
Page 153
3 Language Development
LG3 Describe the nature of language and how it develops
in infancy.
Defining Language
Language’s Rule Systems
How Language Develops
Biological and Environmental Influences
An Interactionist View
In 1799, a nude boy was observed running through the woods in France. The boy was captured when he was 11 years old. He was called the Wild Boy of Aveyron and was believed to have lived in the woods alone for six years (Lane, 1976). When found, he made no effort to communicate. He never learned to communicate effectively. Sadly, a modern-day wild child named Genie was discovered in Los Angeles in 1970. Despite intensive intervention, Genie has never acquired more than a primitive form of language. Both cases—the Wild Boy of Aveyron and Genie—raise questions about the biological and environmental determinants of language, topics that we also will examine later in this chapter. First, though, we need to define language.
DEFINING LANGUAGE
Language is a form of communication—whether spoken, written, or signed—that is based on a system of symbols. Language consists of the words used by a community and the rules for varying and combining them.
Think how important language is in our everyday lives. We need language to speak with others, listen to others, read, and write. Our language enables us to describe past events in detail and to plan for the future. Language lets us pass down information from one generation to the next and create a rich cultural heritage. Language learning involves comprehending a sound system (or sign system for individuals who are deaf), the world of objects, actions, and events, and how units such as words and grammar connect sound and world (Nathan, 2017; Hoffman, 2017; van der Hulst, 2017; Wilcox & Occhino, 2017).
All human languages have some common characteristics (Clark, 2017). These include infinite generativity and organizational rules. Infinite generativity is the ability to produce and comprehend an endless number of meaningful sentences using a finite set of words and rules. Rules describe the way language works. Let’s explore what these rules involve.
Language allows us to communicate with others. What are some important characteristics of language?
©LiAndStudio/Shutterstock
LANGUAGE’S RULE SYSTEMS
When nineteenth-century American writer Ralph Waldo Emerson said, “The world was built in order, and the atoms march in tune,” he must have had language in mind. Language is highly ordered and organized. The organization involves five systems of rules: phonology, morphology, syntax, semantics, and pragmatics.
Phonology Every language is made up of basic sounds. Phonology is the sound system of the language, including the sounds that are used and how they may be combined (Goswami & Bryant, 2016). For example, English has the initial consonant cluster spr as in spring, but no words begin with the cluster rsp.
Phonology provides a basis for constructing a large and expandable set of words out of two or three dozen phonemes (Nathan, 2017). A phoneme is the basic unit of sound in a language; it is the smallest unit of sound that affects meaning. For example, in English the sound represented by the letter p, as in the words pot and spot, is a phoneme. The /p/ sound is slightly different in the two words, but this variation is not distinguished in English, and therefore the /p/ sound is a single phoneme. In some languages, such as Hindi, the variations of the /p/ sound represent separate phonemes.
Morphology Morphology refers to the units of meaning involved in word formation. A morpheme is a minimal unit of meaning; it is a word or a part of a word that cannot be broken into smaller meaningful parts (Lems, Miller, & Soro, 2017; Payne, 2017). Every word in the English language is made up of one or more morphemes. Some words consist of a single morpheme (for example, help), whereas others are made up of more than one morpheme (for example, helper has two morphemes, help and er, with the morpheme –er meaning “one who”—in this case, “one who helps”). Thus, not all morphemes are words by themselves; for example, pre-, -tion, and –ing are morphemes.
Just as the rules that govern phonology describe the sound sequences that can occur in a language, the rules of morphology describe the way meaningful units (morphemes) can be combined in words (Beck, 2017; Deevy, Leonard, & Marchman, 2017). Morphemes have many jobs in grammar, such as marking tense (for example, “she walks” versus “she walked”) and number (“she walks” versus “they walk”).
Syntax Syntax involves the way words are combined to form acceptable phrases and sentences (Langacker, 2017; Narrog, 2017). If someone says to you, “Bob slugged Tom” or “Bob was slugged by Tom,” you know who did the slugging and who was slugged in each case because you have a syntactic understanding of these sentence structures. You also understand that the sentence, “You didn’t stay, did you?” is a grammatical sentence, but that “You didn’t stay, didn’t you?” is unacceptable and ambiguous.
If you learn another language, English syntax will not get you very far. For example, in English an adjective usually precedes a noun (as in blue sky), whereas in Spanish the adjective usually follows the noun (cielo azul). Despite the differences in their syntactic structures, however, syntactic systems in all of the world’s languages have some common ground Page 154(Hoffman, 2017; Koeneman & Zeijstra, 2017). For example, no language we know of permits sentences like the following one:
The mouse the cat the farmer chased killed ate the cheese.
It appears that language users cannot process subjects and objects arranged in too complex a fashion in a sentence.
Semantics Semantics refers to the meaning of words and sentences. Every word has a set of semantic features, which are required attributes related to meaning (McKeown & others, 2017). Girl and woman, for example, share many semantic features, but they differ semantically in regard to age.
Words have semantic restrictions on how they can be used in sentences (Taylor, 2017). The sentence The bicycle talked the boy into buying a candy bar is syntactically correct but semantically incorrect. The sentence violates our semantic knowledge that bicycles don’t talk.
Pragmatics A final set of language rules involves pragmatics, the appropriate use of language in different contexts. Pragmatics covers a lot of territory (Clark, 2017; Fischer, 2017; Wilce, 2017). When you take turns speaking in a discussion or use a question to convey a command (“Why is it so noisy in here? What is this, Grand Central Station?”), you are demonstrating knowledge of pragmatics. You also apply the pragmatics of English when you use polite language in appropriate situations (for example, when talking to your teacher) or tell stories that are interesting, jokes that are funny, and lies that convince. In each of these cases, you are demonstrating that you understand the rules of your culture for adjusting language to suit the context.
At this point, we have discussed five important rule systems involved in language. An overview of these rule systems is presented in Figure 10.
FIGURE 10 THE RULE SYSTEMS OF LANGUAGE
HOW LANGUAGE DEVELOPS
According to an ancient historian, in the thirteenth century the emperor of Germany, Frederick II, had a cruel idea. He wanted to know what language children would speak if no one talked to them. He selected several newborns and threatened their caregivers with death if they ever talked to the infants. Frederick never found out what language the children spoke because they all died. Today, we are still curious about infants’ development of language, although our experiments and observations are, to say the least, far more humane than the evil Frederick’s.
Whatever language they learn, infants all over the world follow a similar path in language development. What are some key milestones in this development?
Recognizing Language Sounds Long before they begin to learn words, infants can make fine distinctions among the sounds of the language. Page 155In Patricia Kuhl’s (1993, 2000, 2007, 2009, 2011, 2015) research, phonemes from languages all over the world are piped through a speaker for infants to hear (see Figure 11). A box with a toy bear in it is placed where the infant can see it. A string of identical syllables is played; then the syllables are changed (for example, ba ba ba ba, and then pa pa pa pa). If the infant turns its head when the syllables change, the box lights up and the bear dances and drums, rewarding the infant for noticing the change.
FIGURE 11 FROM UNIVERSAL LINGUIST TO LANGUAGE-SPECIFIC LISTENER. In Patricia Kuhl’s research laboratory babies listen to tape-recorded voices that repeat syllables. When the sounds of the syllables change, the babies quickly learn to look at the bear. Using this technique, Kuhl has demonstrated that babies are universal linguists until about 6 months of age, but in their next six months they become language-specific listeners. Does Kuhl’s research give support to the view that either “nature” or “nurture” is the source of language acquisition?
Courtesy of Dr. Patricia Kuhl, Institute for Learning and Brain Sciences, University of Washington
Kuhl’s (2007, 2009, 2011, 2015) research has demonstrated that from birth up to about 6 months of age, infants are “citizens of the world”: They recognize when sounds change most of the time, no matter what language the syllables come from. But over the next six months, infants get even better at perceiving the changes in sounds from their “own” language (the one their parents speak) and gradually lose the ability to recognize differences in sounds that are not important in their own language (Kuhl, 2015; Kuhl & Damasio, 2012). Kuhl (2015) has found that a baby’s brain becomes most open to learning the sounds of a native language at 6 months for vowels and at 9 months for consonants.
Also, in the second half of the first year, infants begin to segment the continuous stream of speech they encounter into words (Ota & Skarabela, 2018; Polka & others, 2018). Initially, they likely rely on statistical information such as the co-occurrence patterns of phonemes and syllables, which allows them to extract potential word forms (Aslin, 2017; Lany & others, 2018; Richtsmeier & Goffman, 2017; Saffran & Kirkham, 2018). For example, discovering that the sequence br occurs more often at the beginning of words while nt is more common at the end of words helps infants detect word boundaries. And as infants extract an increasing number of potential word forms from the speech stream they hear, they begin to associate these with concrete, perceptually available objects in their world (Saffran & Kirkham, 2018). For example, infants might detect that the spoken word “monkey” has a reliable statistical regularity of occurring in the visual presence of an observed monkey but not in the presence of other animals, such as bears (Pace & others, 2016). Thus, statistical learning involves extracting information from the world to learn about the environment.
Richard Aslin (2017) recently emphasized that statistical learning—which involves no instruction, reinforcement, or feedback—is a powerful learning mechanism in infant development. In statistical learning, infants soak up statistical regularities in the world merely through exposure to them (Lany & others, 2018; Monroy & others, 2018; Saffran & Kirkham, 2018).
Babbling and Other Vocalizations Long before infants speak recognizable words, they produce a number of vocalizations. The functions of these early vocalizations are to practice making sounds, to communicate, and to attract attention (Lee & others, 2017). Babies’ sounds go through the following sequence during the first year:
- Crying. Babies cry even at birth. Crying can signal distress, but, as we will discuss in the chapter on “Socioemotional Development in Infancy,” different types of cries signal different things.
- Cooing. Babies first coo at about 2 to 4 months Page 156(Menn & Stoel-Gammon, 2009). These are gurgling sounds that are made in the back of the throat and usually express pleasure during interaction with the caregiver.
- Babbling. In the middle of the first year, babies babble—that is, they produce strings of consonant-vowel combinations, such as “ba, ba, ba, ba.” Infants’ babbling influences the behavior of their caregivers, creating social interaction that facilitates their own communicative development (Albert, Schwade, & Goldstein, 2018). In a recent study, babbling onset predicted when infants would say their first words (McGillion & others, 2017a).
Gestures Infants start using gestures, such as showing and pointing, at about 7 to 15 months of age with a mean age of approximately 11 to 12 months. They may wave bye-bye, nod to mean “yes,” show an empty cup to ask for more milk, and point to a dog to draw attention to it. Some early gestures are symbolic, as when an infant smacks her lips to indicate food or drink. Pointing is regarded by language experts as an important index of the social aspects of language, and it follows this developmental sequence: from pointing without checking on adult gaze to pointing while looking back and forth between an object and the adult (Goldin-Meadow, 2017a, b). Lack of pointing is a significant indicator of problems in the infant’s communication system (Brentari & Goldin-Meadow, 2017; Cooperrider & Goldin-Meadow, 2018; Novack & others, 2018). For example, failure to engage in pointing characterizes many autistic children. Use of the pointing gesture becomes more effective in the second year of life alongside advances in other aspects of language communication.
Long before infants speak recognizable words, they communicate by producing a number of vocalizations and gestures. At approximately what ages do infants begin to produce different types of vocalizations and gestures?
©Don Hammond/Design Pics
Why might gestures such as pointing promote further language development? Infants’ gestures advance their language development since caregivers often talk to them about what they are pointing to. Also, babies’ first words often are for things they have previously pointed to.
First Words Infants understand their first words earlier than they speak them (Pace & others, 2016). As early as 5 months of age, infants recognize their name when someone says it. On average, infants understand about 50 words at about 13 months, but they can’t say this many words until about 18 months (Menyuk, Liebergott, & Schultz, 1995). Thus, in infancy receptive vocabulary (words the child understands) considerably exceeds spoken (or expressive) vocabulary (words the child uses).
A child’s first words include those that name important people (dada), familiar animals (kitty), vehicles (car), toys (ball), food (milk), body parts (eye), clothes (hat), household items (clock), and greeting terms (bye). These were the first words of babies 50 years ago, and they are the first words of babies today. Children often express various intentions with their single words, so that “cookie” might mean, “That’s a cookie” or “I want a cookie.” Nouns are easier to learn because the majority of words in this class are more perceptually accessible than words not in this class (Parish-Morris, Golinkoff, & Hirsh-Pasek, 2013). Think how the noun “car” is so much more concrete and imaginable than the verb “goes,” making the word “car” much easier to acquire than the word “goes.”
The infant’s spoken vocabulary rapidly increases after the first word is spoken (Werker & Gervain, 2013). The average 18-month-old can speak about 50 words, but most 2-year-olds can speak about 200 words. This rapid increase in vocabulary that begins at approximately 18 months is called the vocabulary spurt (Bloom, Lifter, & Broughton, 1985).
Like the timing of a child’s first word, the timing of the vocabulary spurt varies (Lieven, 2008). Figure 12 shows the range for these two language milestones in 14 children. On average, these children said their first word at 13 months and had a vocabulary spurt at 19 months. However, the ages for the first spoken word of individual children varied from 10 to 17 months and for their vocabulary spurt from 13 to 25 months. Also, the spurt actually involves the increase in the rate at which words are learned. That is, early on, a few words are learned every few days, then later on, a few words are learned each day, and eventually many words each day.
What characterizes the infant’s early word learning?
©JGI/Jamie Grill/Blend Images LLCFIGURE 12 VARIATION IN LANGUAGE MILESTONES. What are some possible explanations for variations in the timing of language milestones?
Does early vocabulary development predict later language development? One study found that infant vocabulary development at 16 to 24 months of age was linked to vocabulary, phonological awareness, reading accuracy, and reading comprehension five years later (Duff & others, 2015).
Cross-linguistic differences occur Page 157in word learning (Waxman & others, 2013). Children learning Mandarin Chinese, Korean, and Japanese acquire more verbs earlier in their development than do children learning English. This cross-linguistic difference reflects the greater use of verbs in the language input to children in these Asian languages. Indeed, the language of Korean children is often described as verb friendly and the language of English as noun friendly (Waxman & others, 2013).
Children sometimes overextend or underextend the meanings of the words they use (Woodward & Markman, 1998). Overextension is the tendency to apply a word to objects that are inappropriate for the word’s meaning by going beyond the set of referents an adult would use. For example, children at first may say “dada” not only for “father” but also for other men, strangers, or boys. Another example of overextension is calling any animal with four legs a “dog.” With time, overextensions decrease and eventually disappear. Underextension is the tendency to apply a word too narrowly; it occurs when children fail to use a word to name a relevant event or object. For example, a child might use the word boy to describe a 5-year-old neighbor but not apply the word to a male infant or to a 9-year-old male.
Two-Word Utterances By the time children are 18 to 24 months of age, they usually speak in two-word utterances. To convey meaning with just two words, the child relies heavily on gesture, tone, and context. The wealth of meaning children can communicate with a two-word utterance includes the following (Slobin, 1972):
- Identification: “See doggie.”
- Location: “Book there.”
- Repetition: “More milk.”
- Negation: “Not wolf.”
- Possession: “My candy.”
- Attribution: “Big car.”
- Agent-action: “Mama walk.”
- Action-direct object: “Hit you.”
- Action-indirect object: “Give Papa.”
- Action-instrument: “Cut knife.”
- Question: “Where ball?”
These are examples from children whose first language is English, German, Russian, Finnish, Turkish, or Samoan.
Notice that the two-word utterances omit many parts of speech and are remarkably succinct. In fact, in every language, a child’s first combinations of words have this economical quality; they are telegraphic. Telegraphic speech is the use of short and precise words without grammatical markers such as articles, auxiliary verbs, and other connectives. Telegraphic speech is not limited to two words. “Mommy give ice cream” and “Mommy give Tommy ice cream” also are examples of telegraphic speech.
We have discussed a number of language milestones in infancy; Figure 13 summarizes the approximate ages at which infants typically reach these milestones.
FIGURE 13 SOME LANGUAGE MILESTONES IN INFANCY. Despite considerable variations in the language input received by infants, around the world they follow a similar path in learning to speak.Around the world, most young children learn to speak in two-word utterances at about 18 to 24 months of age. What are some examples of these two-word utterances?
©McPhoto/age fotostock
BIOLOGICAL AND ENVIRONMENTAL INFLUENCES
What makes it possible for infants to reach the milestones of language development described in Figure 13? Everyone who uses language in some way “knows” its rules and has the ability to create an infinite number of words and sentences. Where does this knowledge come from? Is it the product of biology? Is language learned and influenced by experiences?
Biological Influences The ability to speak and understand language requires a certain vocal apparatus as well as a nervous system with certain capabilities. The nervous system and vocal apparatus of humanity’s predecessors changed over hundreds of thousands or millions of years. With advances in the nervous system and vocal structures, Homo sapiens went beyond the grunting and shrieking of other animals Page 158to develop speech (Cataldo, Migliano, & Vinicius, 2018). Although estimates vary, many experts believe that humans acquired language about 100,000 years ago, which in evolutionary time represents a very recent acquisition. It gave humans an enormous edge over other animals and increased the chances of human survival (de Boer & Thompson, 2018; Pinker, 2015).
Some language scholars view the remarkable similarities in how children acquire language all over the world as strong evidence that language has a biological basis. There is evidence that particular regions of the brain are predisposed to be used for language (Coulson, 2017; Schutze, 2017). Two regions involved in language were first discovered in studies of brain-damaged individuals: Broca’s area, an area in the left frontal lobe of the brain involved in producing words (Maher, 2018; Zhang & others, 2017), and Wernicke’s area, a region of the brain’s left hemisphere involved in language comprehension (see Figure 14) (Bruckner & Kammer, 2017; Greenwald, 2018). Damage to either of these areas produces types of aphasia, which is a loss or impairment of language processing. Individuals with damage to Broca’s area have difficulty producing words correctly; individuals with damage to Wernicke’s area have poor comprehension and often produce fluent but incomprehensible speech.
FIGURE 14 BROCA’S AREA AND WERNICKE’S AREA. Broca’s area is located in the frontal lobe of the brain’s left hemisphere, and it is involved in the control of speech. Wernicke’s area is a portion of the left hemisphere’s temporal lobe that is involved in understanding language. How does the role of these areas of the brain relate to lateralization?
Linguist Noam Chomsky (1957) proposed that humans are biologically prewired to learn language at a certain time and in a certain way. He said that children are born into the world with a language acquisition device (LAD), a biological endowment that enables the child to detect certain features and rules of language, including phonology, syntax, and semantics. Children are equipped by nature with the ability to detect the sounds of language, for example, and to follow rules such as how to form plurals and ask questions.
Chomsky’s LAD is a theoretical construct, not a physical part of the brain. Is there evidence for the existence of a LAD? Supporters of the LAD concept cite the uniformity of language milestones across languages and cultures, evidence that children create language even in the absence of well-formed input, and biological substrates of language. But, as we will see, critics argue that even if infants have something like a LAD, it cannot explain the whole story of language acquisition.
Environmental Influences Our coverage of environmental influences on language development in infancy focuses on the important role of social interaction as well as child-directed speech and caregiver strategies.
The Role of Social Interaction Language is not learned Page 159in a social vacuum. Most children are bathed in language from a very early age, unlike the Wild Boy of Aveyron, who never learned to communicate effectively, having lived in social isolation for years. Thus, social cues play an important role in infant language learning (Ahun & others, 2018; McGillion & others, 2017b).
developmental connection
Language
Much of language is processed in the brain’s left hemisphere. Connect to “Physical Development in Infancy.”
The support and involvement of caregivers and teachers greatly facilitate a child’s language learning (Brown & others, 2018; Clark, 2017; Marchman & others, 2018; Weisleder & others, 2018). In one study, both full-term and preterm infants who heard more caregiver talk based on all-day recordings at 16 months of age had better language skills (receptive and expressive language, language comprehension) at 18 months of age (Adams & others, 2018). And in another study, when mothers immediately smiled and touched their 8-month-old infants after they babbled, the infants subsequently made more complex speech-like sounds than when mothers responded to their infants in a random manner (Goldstein, King, & West, 2003) (see Figure 15).
FIGURE 15 SOCIAL INTERACTION AND BABBLING. One study focused on two groups of mothers and their 8-month-old infants (Goldstein, King, & West, 2003). One group of mothers was instructed to smile and touch their infants immediately after the babies cooed and babbled; the other group was also told to smile and touch their infants but in a random manner, unconnected to sounds the infants made. The infants whose mothers immediately responded in positive ways to their babbling subsequently made more complex, speechlike sounds, such as “da” and “gu.” The research setting for this study, which underscores how important caregivers are in the early development of language, is shown here.
Courtesy of Dr. Michael Goldstein
Michael Tomasello (2006, 2014) stresses that young children are intensely interested in their social world and that early in their development they can understand the intentions of other people. His interaction view of language emphasizes that children learn language in specific contexts. For example, when a toddler and a father are jointly focused on a book, the father might say, “See the birdie.” In this case, even a toddler understands that the father intends to name something and knows to look in the direction of the pointing. Through this kind of joint attention, early in their development children are able to use their social skills to acquire language (Mastin & Vogt, 2016). One study revealed that joint attention at 12 and 18 months predicted language skills at 24 months of age (Mundy & others, 2007). Also, in a study involving joint attention, infants’ eye-gaze behaviors during Spanish tutoring sessions at 9.5 to 10.5 months of age predicted their second-language phonetic learning at 11 months of age, indicating a strong influence of social interaction at the earliest ages of learning a second language (Conboy & others, 2015).
Researchers have also found that the child’s vocabulary development is linked to the family’s socioeconomic status and the type of talk that parents direct to their children. Betty Hart and Todd Risley (1995) observed the language environments of children whose parents were professionals and children whose parents were on welfare (public assistance). Compared with the professional parents, the parents on welfare talked much less to their young children, talked less about past events, and provided less elaboration. As indicated in Figure 16, the children of the professional parents had a much larger vocabulary at 36 months of age than the children of the welfare parents. One study also found that at 18 to 24 months of age, infants in low-SES families already had a smaller vocabulary Page 160and less efficient language processing than their infant counterparts in middle-SES families (Fernald, Marchman, & Weisleder, 2013).
FIGURE 16 LANGUAGE INPUT IN PROFESSIONAL AND WELFARE FAMILIES AND YOUNG CHILDREN’S VOCABULARY DEVELOPMENT. (a) In this study (Hart & Rísley, 1995), parents from professional families talked with their young children more than parents from welfare families. (b) All of the children learned to talk, but children from professional families developed vocabularies that were twice as large as those of children from welfare families. Thus, by the time children go to preschool, they already have experienced considerable differences in language input in their families and developed different levels of vocabulary that are linked to their socioeconomic context. Does this study indicate that poverty caused deficiencies in vocabulary development?
Other research has linked how much mothers speak to their infants with the size of the infants’ vocabularies. For example, in one study by Janellen Huttenlocher and her colleagues (1991), infants whose mothers spoke more often to them had markedly higher vocabularies. By the second birthday, vocabulary differences were substantial. A study of low-SES Spanish-speaking families found that infants who experienced more child-directed speech were better at processing familiar words in real time and had larger vocabularies at 2 years of age (Weisleder & Fernald, 2013).
A father using child-directed speech on the island of Tanna in the South Pacific Ocean.
©Nick Perry/AP Images
However, a study of 1- to 3-year-old children living in low-income families found that the sheer amount of maternal talk was not the best predictor of a child’s vocabulary growth (Pan & others, 2005). Rather, it was maternal language and literacy skills and mothers’ diversity of vocabulary use that best predicted children’s vocabulary development. For example, when mothers used a more diverse vocabulary when talking with their children, their children’s vocabulary benefited, but their children’s vocabulary was not related to the total amount of their talkativeness with their children. Also, mothers who frequently used pointing gestures had children with a greater vocabulary. Pointing usually occurs in concert with speech, and it may enhance the meaning of mothers’ verbal input to their children. These research studies and others (NICHD Early Child Care Research Network, 2005; Perkins, Finegood, & Swain, 2013) demonstrate the important effect that early speech input and poverty can have on the development of a child’s language skills.
Given that social interaction is critical for infants to learn language effectively, might they also be able to learn language effectively through television and videos? Researchers have found that infants and young children cannot effectively learn language (phonology or words) from television or videos (Kuhl, 2007; Roseberry & others, 2009; Zosh & others, 2017). A study of toddlers found that frequent viewing of television increased the risk of delayed language development (Lin & others, 2015). Thus, just hearing language is not enough even when infants seemingly are fully engaged in the experience. However, one study revealed that Skype provides some improvement in child language learning over videos and TV (Roseberry, Hirsh-Pasek, & Golinkoff, 2014), and older children can use information provided from television in their language development.
Also, recently the American Academy of Pediatrics (AAP) (2016) concluded that for infants from 15 months to 2 years of age, evidence indicates that if parents co-watch educational videos with their infant and communicate with the infant about the information being watched, this shared activity can benefit the infant’s development. These findings suggest that when parents treat an educational video or app like a picture book infants can benefit from it. However, the AAP still recommends that children under 18 months of age not watch videos alone.
Child-Directed Speech and Other Caregiver Strategies One intriguing component of the young child’s linguistic environment is child-directed speech (also referred to as “parentese”), which is language spoken with a higher-than-normal pitch, slower tempo, and exaggerated intonation, with simple words and sentences (Broesch & Bryant, 2018; Hayashi & Mazuka, 2017; Sulpizio & others, 2018). It is hard to use child-directed speech when not in the presence of a baby, but parents shift into it when they start talking to a baby. Much of this is automatic and something most parents are not aware they are doing. Child-directed speech serves the important functions of capturing the infant’s attention, maintaining communication and social interaction between infants and caregivers, and providing infants with information about their native language by heightening differences between speech directed to children and adults (Golinkoff & others, 2015). Even 4-year-olds speak in simpler ways to 2-year-olds than to their 4-year-old friends. In recent research, child-directed speech in a one-to-one social context at 11 to 14 months of age was related to productive vocabulary at 2 years of age for Spanish-English bilingual infants across languages and in each individual language (Ramirez-Esparza, Garcia-Sierra, & Kuhl, 2017). Most research on child-directed speech has involved mothers, but a recent study in several North American urban areas and a small society on the island of Tanna in the South Pacific Ocean found that fathers in both types of contexts engaged in child-directed speech with their infants (Broesch & Bryant, 2018).
Adults often use strategies other than child-directed speech to enhance the child’s acquisition of language, including recasting, expanding, and labeling:
- Recasting is rephrasing something the child has said that might lack the appropriate morphology or contain some other error. The adult restates the child’s immature utterance in the form of a fully grammatical sentence. For example, if a 2-year-old says, “dog bark,” the adult can respond by saying, “Oh, you heard the dog barking!” The adult sentence provides an Page 161acknowledgement that the child was heard and then adds the morphology (/ing/) and the article (the) that the child’s utterance lacked.
- Expanding is adding information to a child’s incomplete utterance. For example, a child says, “Doggie eat,” and the parent replies, “Yes, the dog is eating his food out of his special dish.”
- Labeling is naming objects that children seem interested in. Young children are forever being asked to identify the names of objects. Roger Brown (1968) called this “the original word game.” Children want more than the names of objects, though; they often want information about the object too.
Parents use these strategies naturally and in meaningful conversations. Parents do not need to use a particular method to teach their children to talk, even for children who are slow in learning language. Children usually benefit when parents follow the child’s lead, talking about things the child is interested in at the moment, and when parents provide information that children can process. If children are not ready to take in some information, they are likely to let you know (perhaps by turning away). Thus, giving the child more information is not always better.
What characterizes shared reading in the lives of infants, toddlers, and young children?
©Elyse Lewin/Getty Images
Remember that encouragement of language development during parents’ interaction with their children, not drill and practice, is the key. Language development is not a simple matter of imitation and reinforcement.
Infants, toddlers, and young children benefit when adults read books to and with them (shared reading) (Brown & others, 2018; Marjanovic-Umek, Fekonja-Peklaj, & Socan, 2017; Sinclair & others, 2018; Wesseling, Christmann, & Lachmann, 2017). Storybook reading especially benefits children when parents extend the meaning of the text by discussing it with children and encouraging them to ask and answer questions (Harris, Golinkoff, & Hirsh-Pasek, 2011). In one study, a majority of U.S. mothers in low-income families reported that they were reading to their infants and toddlers with some regularity (Raikes & others, 2006). In this study, non-Latino White, more highly educated mothers who were parenting a first-born child were more likely to read books to their infants and toddlers than were African American and Latino mothers who were parenting later-born children. Reading daily to children at 14 to 24 months of age was positively related to the children’s language and cognitive development at 36 months of age. And in one study, Japanese mothers who used more elaborative information-seeking responses during joint picture-book reading at 20 months had children with a better productive vocabulary at 27 months (Murase, 2014). To read further about ways that parents can facilitate children’s language development, see Connecting Development to Life.
AN INTERACTIONIST VIEW
If language acquisition depended only on biology, then the Wild Boy of Aveyron and Genie (discussed earlier in the chapter) should have talked without difficulty. A child’s experiences influence language acquisition. But we have seen that language does have strong biological foundations. No matter how much you converse with a dog, it won’t learn to talk. In contrast, children are biologically prepared to learn language. Children all over the world acquire language milestones at about the same time and in about the same order. However, there are cultural variations in the type of support given to children’s language development. For example, caregivers in the Kaluli culture prompt young children to use a loud voice, to call out particular morphemes that direct the speech act the child is performing, and to refer to names, kinship relations, and places where there has been a shared past experience that indicates a closeness to the person being addressed (Ochs & Schieffelin, 2008; Schieffelin, 2005).
Environmental influences are also very important in developing competence in language (Ahun & others, 2018; Clark, 2017; Marchman & others, 2017; Pickard & others, 2018). Children whose parents provide them with a rich verbal environment show many positive benefits (Vallotton & others, 2017; Weisleder & others, 2018). Parents who pay attention to what their children are trying to say, expand their children’s utterances, read to them, and label things in the environment, are providing valuable benefits for them (Capone Singleton, 2018; Yazejian & others, 2017).
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connecting development to life
How Parents Can Facilitate Infants’ and Toddlers’ Language Development
Linguist Naomi Baron (1992) in Growing Up with Language, developmental psychologists Roberta Golinkoff and Kathy Hirsh-Pasek (2000) in How Babies Talk, and more recently Ellen Galinsky (2010) in Mind in the Making have provided ideas to help parents facilitate their infants’ and toddlers’ language development. Following is a summary of their suggestions:
- Be an active conversational partner. Talk to your baby from the time it is born. Initiate conversation with the baby. If the baby is in an all-day child-care program, ensure that the baby receives adequate language stimulation from adults.
- Narrate your daily activities to the baby as you do them. For example, talk about how you will put the baby in a high chair for lunch and ask what she would like to eat, and so on.
- Talk in a slowed-down pace and don’t worry about how you sound to other adults when you talk to your baby. Talking in a slowed-down pace will help your baby detect words in the sea of sounds they experience. Babies enjoy and attend to the high-pitched sound of child-directed speech.
- Use parent-look and parent-gesture, and name what you are looking at. When you want your child to pay attention to something, look at it and point to it. Then name it—for example, you might say, “Look, Alex, there’s an airplane.”
- When you talk with infants and toddlers, be simple, concrete, and repetitive. Don’t try to talk to them in abstract, high-level ways and think you have to say something new or different all of the time. Using familiar words often will help them remember the words.
- Play games. Use word games like peek-a-boo and pat-a-cake to help infants learn words.
- Remember to listen. Since toddlers’ speech is often slow and laborious, parents are often tempted to supply words and thoughts for them. Be patient and let toddlers express themselves, no matter how painstaking the process is or how great a hurry you are in.
- Expand and elaborate language abilities and horizons with infants and toddlers. Ask questions that encourage answers other than “yes” or “no.” Actively repeat, expand, and recast the utterances. Your toddler might say, “Dada.” You could follow with, “Where’s Dada?” and then you might continue, “Let’s go find him.”
- Adjust to your child’s idiosyncrasies instead of working against them. Many toddlers have difficulty pronouncing words and making themselves understood. Whenever possible, make toddlers feel that they are being understood.
- Resist making normative comparisons. Be aware of the ages at which your child reaches specific milestones (such as the first word, first 50 words), but do not measure this development rigidly against that of other children. Such comparisons can bring about unnecessary anxiety.
It is a good idea for parents to begin talking to their babies at the start. The best language teaching occurs when the talking begins before the infant becomes capable of intelligible speech. What are some other guidelines for parents to follow in helping their infants and toddlers develop their language skills?
©John Carter/Science Source
The first suggestion above to parents of infants is to “be an active conversational partner.” What did you learn earlier in the chapter about the amount of conversation mothers have with their infants? Does the amount of conversation or the mother’s literacy skills and vocabulary diversity have more of a positive effect on infants’ vocabulary?
An interactionist view emphasizes that both biology and experience contribute to language development (Adams & others, 2017; McGillion & others, 2017b; Raymer & Gonzalez Rothi, 2018; Suskind & others, 2018). How much of language acquisition is biologically determined and how much depends on interaction with others is a subject of debate among linguists and psychologists. However, all agree that both biological capacity and relevant experience are necessary (Green & others, 2017; Novack & others, 2018; Peterson & others, 2017; Pickard & others, 2018; Schwab & others, 2018; Warren & others, 2017).
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Review Connect Reflect
LG3 Describe the nature of language and how it develops in infancy.
Review
- What is language?
- What are language’s rule systems?
- How does language develop in infancy?
- What are some biological and environmental influences on language?
- To what extent do biological and environmental influences interact to produce language development?
Connect
- The more years children spend living in poverty, the more their physiological indices of stress are elevated. In this chapter, you learned about the effects of SES on children’s language acquisition and vocabulary building. How might these effects influence children’s school performance?
Reflect Your Own Personal Journey of Life
- Would it be a good idea for you as a parent to hold large flash cards of words in front of your baby for several hours each day to help the baby learn language and to raise the baby’s intelligence? Why or why not? What do you think Piaget would say about this activity?
topical connections looking forward
Advances in infants’ cognitive development are linked to their socioemotional development. In subsequent chapters, you will learn about the infant’s developing social orientation and understanding, which involve perceiving people as engaging in intentional and goal-directed behavior, joint attention, and cooperation. You will read about two major theorists—Piaget and Vygotsky—and compare their views of how young children’s thinking advances. You will see how young children become more capable of sustaining their attention; learn about the astonishing rate at which preschool children’s vocabulary expands; and explore variations in early childhood education.
reach your learning goals
Cognitive Development in Infancy
1 Piaget’s Theory of Infant Development
Cognitive Processes
The Sensorimotor Stage
Evaluating Piaget’s Sensorimotor Stage
LG1 Summarize and evaluate Piaget’s theory of infant development.
- In Piaget’s theory, children actively construct their own cognitive worlds, building mental structures to adapt to their world. Schemes are actions or mental representations that organize knowledge. Behavioral schemes (physical activities) characterize infancy, whereas mental schemes (cognitive activities) develop in childhood. Assimilation occurs when children use their existing schemes to deal with new information; accommodation refers to children’s adjustment of their schemes in the face of new information. Through organization, children group isolated behaviors into a higher-order, more smoothly functioning cognitive system.
- Equilibration is a mechanism Piaget proposed to explain how children shift from one cognitive stage to the next. As children experience cognitive conflict in trying to understand the world, they use assimilation and accommodation to attain equilibrium. The result is a new stage of thought.
- According to Piaget, there are four qualitatively different stages of thought. The first of these, the sensorimotor stage, is described in this chapter. The other three stages are discussed in subsequent chapters.
- In sensorimotor thought, the Page 164first of Piaget’s four stages, the infant organizes and coordinates sensations with physical movements. The stage lasts from birth to about 2 years of age.
- Sensorimotor thought has six substages: simple reflexes; first habits and primary circular reactions; secondary circular reactions; coordination of secondary circular reactions; tertiary circular reactions, novelty, and curiosity; and internalization of schemes. One key accomplishment of this stage is object permanence, the ability to understand that objects continue to exist even when the infant is no longer observing them. Another aspect involves infants’ understanding of cause and effect.
- Piaget opened up a whole new way of looking at infant development in terms of coordinating sensory input with motoric actions. In recent decades, revisions of Piaget’s view have been proposed based on research. For example, researchers have found that a stable and differentiated perceptual world is established earlier than Piaget envisioned, and infants begin to develop concepts earlier as well.
- The nature-nurture issue in regard to infant cognitive development continues to be debated. Spelke endorses a core knowledge approach which states that infants are born with domain-specific innate knowledge systems. Critics argue that Spelke has not given adequate attention to early experiences that infants have.
2 Learning, Attention, Remembering, and Conceptualizing
LG2 Describe how infants learn, focus attention, remember, and conceptualize.
Conditioning
Imitation
Memory
Attention
Concept Formation
and Categorization
- Operant conditioning techniques have been especially useful to researchers in demonstrating infants’ perception and retention of information about perceptual-motor actions.
- Attention is the focusing of mental resources on select information, and in infancy attention is closely linked with habituation. In the first year, much of attention is of the orienting/investigative type, but sustained attention also becomes important.
- Habituation is the repeated presentation of the same stimulus, causing reduced attention to the stimulus. If a different stimulus is presented and the infant pays increased attention to it, dishabituation is occurring.
- Joint attention plays an important role in infant development, especially in the infant’s acquisition of language.
- Memory is the retention of information over time. Infants as young as 2 to 6 months of age can retain information about perceptual-motor actions. However, many experts argue that what we commonly think of as memory (consciously remembering the past) does not occur until the second half of the first year of life. By the end of the second year, long-term memory is more substantial and reliable.
- The hippocampus and frontal lobes of the brain are involved in development of explicit memory in infancy. The phenomenon of not being able to remember events that occurred before the age of 3—known as infantile or childhood amnesia—may be due to the immaturity of the prefrontal lobes of the brain at that age.
- Meltzoff has shown that newborns can match their behaviors (such as protruding their tongue) to those of a model. His research also shows that deferred imitation occurs as early as 9 months of age.
- Mandler argues that it is not until about 7 to 9 months of age that infants form conceptual categories, although we do not know precisely when concept formation begins. Infants’ first concepts are broad. Over the first two years of life, these broad concepts gradually become more differentiated.
3 Language Development
LG3 Describe the nature of language and how it develops
in infancy.
Defining Language
Language’s Rule Systems
How Language Develops
An Interactionist View
Biological and Environmental Influences
- Language is a form of communication, whether spontaneous, written, or signed, that is based on a system of symbols. Language consists of the words used by a community and the rules for varying and combining them. Language is characterized by infinite generativity.
- Phonology is the sound system Page 165of a language, including the sounds that are used and how they may be combined. Morphology refers to the units of meaning involved in word formation. Syntax is the way words are combined to form acceptable phrases and sentences. Semantics involves the meaning of words and sentences. Pragmatics is the appropriate use of language in different contexts.
- Among the milestones in infant language development are crying (birth), cooing (1 to 2 months), babbling (6 months), making the transition from universal linguist to language-specific listener (6 to 12 months), using gestures (8 to 12 months), comprehending words (8 to 12 months), speaking one’s first word (13 months), undergoing a vocabulary spurt (19 months), rapidly expanding one’s understanding of words (18 to 24 months), and producing two-word utterances (18 to 24 months).
- In evolution, language clearly gave humans an enormous advantage over other animals and increased their chances of survival. Broca’s area and Wernicke’s area are important locations for language processing in the brain’s left hemisphere.
- Chomsky argues that children are born with the ability to detect basic features and rules of language. In other words, they are biologically equipped to learn language with a prewired language acquisition device (LAD). Adults help children acquire language by engaging in child-directed speech, recasting, expanding, and labeling.
- Environmental influences are demonstrated by differences in the language development of children as a consequence of being exposed to different language environments in the home. Parents should talk extensively with an infant, especially about what the baby is attending to.
- Today, most language researchers believe that children everywhere arrive in the world with special social and linguistic capacities that make language acquisition not just likely but inevitable for virtually all children. How much of the language is biologically determined, and how much depends on interaction with others, is a subject of debate among linguists and psychologists. However, all agree that both biological capacity and relevant experience are necessary.
key terms
coordination of secondary circular reactions
first habits and primary circular reactions
language acquisition device (LAD)
tertiary circular reactions, novelty, and curiosity
key people
Renee Baillargeon
Naomi Baron
Patricia Bauer
Roger Brown
Noam Chomsky
Ellen Galinsky
Eleanor Gibson
Roberta Golinkoff
Betty Hart
Kathy Hirsh-Pasek
Janellen Huttenlocher
Patricia Kuhl
Jean Mandler
Andrew Meltzoff
Jean Piaget
Todd Risley
Carolyn Rovee-Collier
Elizabeth Spelke
Michael Tomasello
