Latisha experienced menarche when she was 8 years old. she experienced:

section six

In no order of things is adolescence the simple time of life.

—Jean Erskine Stewart

American Writer, 20th Century

Adolescence

Adolescents try on one face after another, seeking to find a face of their own. Their generation of young people is the fragile cable by which the best and the worst of their parents’ generation is transmitted to the present. In the end, there are only two lasting bequests parents can leave youth—one is roots, the other wings. This section contains two chapters: “Physical and Cognitive Development in Adolescence” and “Socioemotional Development in Adolescence.”

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chapter 11

PHYSICAL AND COGNITIVE DEVELOPMENT IN ADOLESCENCE

chapter outline

1 The Nature of Adolescence

Learning Goal 1 Discuss the nature of adolescence.

2 Physical Changes

Learning Goal 2 Describe the changes involved in puberty, as well as changes in the brain and sexuality during adolescence.

Puberty

The Brain

Adolescent Sexuality

3 Issues in Adolescent Health

Learning Goal 3 Identify adolescent problems related to health, substance use and abuse, and eating disorders.

Adolescent Health

Substance Use and Abuse

Eating Disorders

4 Adolescent Cognition

Learning Goal 4 Explain cognitive changes in adolescence.

Piaget’s Theory

Adolescent Egocentrism

Information Processing

5 Schools

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

High School

Extracurricular Activities

Service Learning

image1 ©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).

image2 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.

image3Growing 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.

image4 ©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.

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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.

image5 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.

image6 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.

image7 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).

image8 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.

image9 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).

image10 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).

image11 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).

image12Psychologists are exploring ways to encourage adolescents to make less risky sexual decisions. Here an adolescent participates in an interactive video session developed by