physical and cognitive changes of adolescence

chapter 11 Physical and Cognitive Development in Adolescence

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The dramatic physical and cognitive changes of adolescence make it both an exhilarating and apprehensive period of development. Although their bodies are full-grown and sexually mature, these exuberant teenagers have many skills to acquire and hurdles to surmount before they are ready for full assumption of adult roles.

chapter outline

·   PHYSICAL DEVELOPMENT

·   Conceptions of Adolescence

·   The Biological Perspective

·   The Social Perspective

·   A Balanced Point of View

·   Puberty: The Physical Transition to Adulthood

·   Hormonal Changes

·   Body Growth

·   Motor Development and Physical Activity

·   Sexual Maturation

·   Individual Differences in Pubertal Growth

·   Brain Development

·   Changing States of Arousal

·   The Psychological Impact of Pubertal Events

·   Reactions to Pubertal Changes

·   Pubertal Change, Emotion, and Social Behavior

·   Pubertal Timing

·   Health Issues

·   Nutritional Needs

·   Eating Disorders

·   Sexuality

·   Sexually Transmitted Diseases

·   Adolescent Pregnancy and Parenthood

·   Substance Use and Abuse

· ■  SOCIAL ISSUES: HEALTH  Lesbian, Gay, and Bisexual Youths: Coming Out to Oneself and Others

·   COGNITIVE DEVELOPMENT

·   Piaget’s Theory: The Formal Operational Stage

·   Hypothetico-Deductive Reasoning

·   Propositional Thought

·   Follow-Up Research on Formal Operational Thought

·   An Information-Processing View of Adolescent Cognitive Development

·   Scientific Reasoning: Coordinating Theory with Evidence

·   How Scientific Reasoning Develops

·   Consequences of Adolescent Cognitive Changes

·   Self-Consciousness and Self-Focusing

·   Idealism and Criticism

·   Decision Making

·   Sex Differences in Mental Abilities

·   Verbal Abilities

·   Mathematical Abilities

· ■  BIOLOGY AND ENVIRONMENT  Sex Differences in Spatial Abilities

·   Learning in School

·   School Transitions

·   Academic Achievement

·   Dropping Out

· ■  SOCIAL ISSUES: EDUCATION  Media Multitasking Disrupts Attention and Learning

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On Sabrina’s eleventh birthday, her friend Joyce gave her a surprise party, but Sabrina seemed somber during the celebration. Although Sabrina and Joyce had been close friends since third grade, their relationship was faltering. Sabrina was a head taller and some 20 pounds heavier than most girls in her sixth-grade class. Her breasts were well-developed, her hips and thighs had broadened, and she had begun to menstruate. In contrast, Joyce still had the short, lean, flat-chested body of a school-age child.

Ducking into the bathroom while the other girls put candles on the cake, Sabrina frowned at her image in the mirror. “I’m so big and heavy,” she whispered. At church youth group on Sunday evenings, Sabrina broke away from Joyce and joined the eighth-grade girls. Around them, she didn’t feel so large and awkward.

Once a month, parents gathered at Sabrina’s and Joyce’s school to discuss child-rearing concerns. Sabrina’s parents, Franca and Antonio, attended whenever they could. “How you know they are becoming teenagers is this,” volunteered Antonio. “The bedroom door is closed, and they want to be alone. Also, they contradict and disagree. I tell Sabrina, ‘You have to go to Aunt Gina’s on Saturday for dinner with the family.’ The next thing I know, she’s arguing with me.”

Sabrina has entered  adolescence , the transition between childhood and adulthood. In industrialized societies, the skills young people must master are so complex and the choices confronting them so diverse that adolescence is greatly extended. But around the world, the basic tasks of this period are much the same. Sabrina must accept her full-grown body, acquire adult ways of thinking, attain greater independence from her family, develop more mature ways of relating to peers of both sexes, and begin to construct an identity—a secure sense of who she is in terms of sexual, vocational, moral, ethnic, religious, and other life values and goals.

The beginning of adolescence is marked by  puberty , a flood of biological events leading to an adult-sized body and sexual maturity. As Sabrina’s reactions suggest, entry into adolescence can be an especially trying time for some young people. In this chapter, we trace the events of puberty and take up a variety of health concerns—physical exercise, nutrition, sexual activity, substance abuse, and other challenges that many teenagers encounter on the path to maturity.

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Adolescence also brings with it vastly expanded powers of reasoning. Teenagers can grasp complex scientific and mathematical principles, grapple with social and political issues, and delve deeply into the meaning of a poem or story. The second part of this chapter traces these extraordinary changes from both Piaget’s and the information-processing perspective. Next, we examine sex differences in mental abilities. Finally, we turn to the main setting in which adolescent thought takes shape: the school.

PHYSICAL DEVELOPMENT

image4 Conceptions of Adolescence

Why is Sabrina self-conscious, argumentative, and in retreat from family activities? Historically, theorists explained the impact of puberty on psychological development by resorting to extremes—either a biological or a social explanation. Today, researchers realize that biological and social forces jointly determine adolescent psychological change.

The Biological Perspective

TAKE A MOMENT…  Ask several parents of young children what they expect their sons and daughters to be like as teenagers. You will probably get answers like these: “Rebellious and irresponsible,” “Full of rages and tempers.” This widespread storm-and-stress view dates back to major early-twentieth-century theorists. The most influential, G. Stanley Hall, based his ideas on Darwin’s theory of evolution. Hall ( 1904 ) described adolescence as a period so turbulent that it resembled the era in which humans evolved from savages into civilized beings. Similarly, in Freud’s psychosexual theory, sexual impulses reawaken in the genital stage, triggering psychological conflict and volatile behavior. As adolescents find intimate partners, inner forces gradually achieve a new, mature harmony, and the stage concludes with marriage, birth, and child rearing. In this way, young people fulfill their biological destiny: sexual reproduction and survival of the species.

The Social Perspective

Contemporary research suggests that the storm-and-stress notion of adolescence is exaggerated. Certain problems, such as eating disorders, depression, suicide, and lawbreaking, do occur more often than earlier (Farrington,  2009 ; Graber,  2004 ). But the overall rate of serious psychological disturbance rises only slightly from childhood to adolescence, reaching 15 to 20 percent (Merikangas et al.,  2010 ). Though much greater than the adulthood rate (about 6 percent), emotional turbulence is not a routine feature of the teenage years.

The first researcher to point out the wide variability in adolescent adjustment was anthropologist Margaret Mead ( 1928 ). She returned from the Pacific islands of Samoa with a startling conclusion: Because of the culture’s relaxed social relationships and openness toward sexuality, adolescence “is perhaps the pleasantest time the Samoan girl (or boy) will ever know” ( p. 308 ). Mead offered an alternative view in which the social environment is entirely responsible for the range of teenage experiences, from erratic and agitated to calm and stress-free. Later researchers found that Samoan adolescence was not as untroubled as Mead had assumed (Freeman,  1983 ). Still, she showed that to understand adolescent development, researchers must pay greater attention to social and cultural influences.

A Balanced Point of View

Today we know that biological, psychological, and social forces combine to influence adolescent development (Susman & Dorn,  2009 ). Biological changes are universal—found in all primates and all cultures. These internal stresses and the social expectations accompanying them—that the young person give up childish ways, develop new interpersonal relationships, and take on greater responsibility—are likely to prompt moments of uncertainty, self-doubt, and disappointment in all teenagers. Adolescents’ prior and current experiences affect their success in surmounting these challenges.

At the same time, the length of adolescence and its demands and pressures vary substantially among cultures. Most tribal and village societies have only a brief intervening phase between childhood and full assumption of adult roles (Weisfield,  1997 ). In industrialized nations, young people face prolonged dependence on parents and postponement of sexual gratification while they prepare for a productive work life. As a result, adolescence is greatly extended—so much so that researchers commonly divide it into three phases:

· 1. Early adolescence (11–12 to 14 years): This is a period of rapid pubertal change.

· 2. Middle adolescence (14 to 16 years): Pubertal changes are now nearly complete.

· 3. Late adolescence (16 to 18 years): The young person achieves full adult appearance and anticipates assumption of adult roles.

The more the social environment supports young people in achieving adult responsibilities, the better they adjust. For all the biological tensions and uncertainties about the future that teenagers feel, most negotiate this period successfully. With this in mind, let’s look closely at puberty, the dawning of adolescent development.

image5 Puberty: The Physical Transition to Adulthood

The changes of puberty are dramatic: Within a few years, the body of the school-age child is transformed into that of a full-grown adult. Genetically influenced hormonal processes regulate pubertal growth. Girls, who have been advanced in physical maturity since the prenatal period, reach puberty, on average, two years earlier than boys.

Hormonal Changes

The complex hormonal changes that underlie puberty occur gradually and are under way by age 8 or 9. Secretions of growth hormone (GH) and thyroxine (see  Chapter 7  page 219 ) increase, leading to tremendous gains in body size and to attainment of skeletal maturity.

Sexual maturation is controlled by the sex hormones. Although we think of estrogens as female hormones and androgens as male hormones, both types are present in each sex but in different amounts. The boy’s testes release large quantities of the androgen testosterone, which leads to muscle growth, body and facial hair, and other male sex characteristics. Androgens (especially testosterone for boys) exert a GH-enhancing effect, contributing greatly to gains in body size. Because the testes secrete small amounts of estrogen as well, 50 percent of boys experience temporary breast enlargement. In both sexes, estrogens also increase GH secretion, adding to the growth spurt and, in combination with androgens, stimulating gains in bone density, which continue into early adulthood (Cooper, Sayer, & Dennison,  2006 ; Styne,  2003 ).

Estrogens released by girls’ ovaries cause the breasts, uterus, and vagina to mature, the body to take on feminine proportions, and fat to accumulate. Estrogens also contribute to regulation of the menstrual cycle. Adrenal androgens, released from the adrenal glands on top of each kidney, influence girls’ height spurt and stimulate growth of underarm and pubic hair. They have little impact on boys, whose physical characteristics are influenced mainly by androgen and estrogen secretions from the testes.

As you can see, pubertal changes are of two broad types: (1) overall body growth and (2) maturation of sexual characteristics. We have seen that the hormones responsible for sexual maturity also affect body growth, making puberty the time of greatest sexual differentiation since prenatal life.

Body Growth

The first outward sign of puberty is the rapid gain in height and weight known as the  growth spurt . On average, it is under way for North American girls shortly after age 10, for boys around age 12½. Because estrogens trigger and then restrain GH secretion more readily than androgens, the typical girl is taller and heavier during early adolescence (Archibald, Graber, & Brooks-Gunn,  2006 ; Bogin,  2001 ). At age 14, however, she is surpassed by the typical boy, whose adolescent growth spurt has now started, whereas hers is almost finished. Growth in body size is complete for most girls by age 16 and for boys by age 17½, when the epiphyses at the ends of the long bones close completely (see  Chapter 7  page 217 ). Altogether, adolescents add 10 to 11 inches in height and 50 to 75 pounds—nearly 50 percent of adult body weight.  Figure 11.1  on  page 364  illustrates pubertal changes in general body growth.

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Sex differences in pubertal growth are obvious among these 11-year-olds. Compared with the boys, the girls are taller and more mature-looking.

Body Proportions.

During puberty, the cephalocaudal growth trend of infancy and childhood reverses. The hands, legs, and feet accelerate first, followed by the torso, which accounts for most of the adolescent height gain. This pattern helps explain why early adolescents often appear awkward and out of proportion—long-legged, with giant feet and hands.

Large sex differences in body proportions also appear, caused by the action of sex hormones on the skeleton. Boys’ shoulders broaden relative to the hips, whereas girls’ hips broaden relative to the shoulders and waist. Of course, boys also end up larger than girls, and their legs are longer in relation to the rest of the body—mainly because boys have two extra years of preadolescent growth, when the legs are growing the fastest.

Muscle–Fat Makeup and Other Internal Changes.

Sabrina worried about her weight because compared with her later-developing girlfriends, she had accumulated much more fat. Around age 8, girls start to add fat on their arms, legs, and trunk, a trend that accelerates between ages 11 and 16. In contrast, arm and leg fat decreases in adolescent boys. Although both sexes gain in muscle, this increase is much greater in boys, who develop larger skeletal muscles, hearts, and lung capacity (Rogol, Roemmich, & Clark,  2002 ). Also, the number of red blood cells—and therefore the ability to carry oxygen from the lungs to the muscles—increases in boys but not in girls. Altogether, boys gain far more muscle strength than girls, a difference that contributes to teenage boys’ superior athletic performance (Ramos et al.,  1998 ).

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FIGURE 11.1 Body growth during adolescence.

Because the pubertal growth spurt takes place earlier for girls than for boys, Kate reached her adult body size earlier than Steven. Rapid pubertal growth is accompanied by large sex differences in body proportions.

Motor Development and Physical Activity

Puberty brings steady improvements in gross motor performance, but the pattern of change differs for boys and girls. Girls’ gains are slow and gradual, leveling off by age 14. In contrast, boys show a dramatic spurt in strength, speed, and endurance that continues through the teenage years. By midadolescence, few girls perform as well as the average boy in running speed, broad jump, or throwing distance, and practically no boys score as low as the average girl (Haywood & Getchell,  2005 ; Malina & Bouchard,  1991 ).

Because girls and boys are no longer well-matched physically, gender-segregated physical education usually begins in middle school. Athletic options for both sexes expand as new sports—including track and field, wrestling, tackle football, weight lifting, floor hockey, archery, tennis, and golf—are added to the curriculum.

Among boys, athletic competence is strongly related to peer admiration and self-esteem. Some adolescents become so obsessed with physical prowess that they turn to performance-enhancing drugs. In recent large-scale studies, about 8 percent of U.S. high school seniors, mostly boys, reported using creatine, an over-the-counter substance that enhances short-term muscle power but carries a risk of serious side effects, including muscle tissue disease, brain seizures, and heart irregularities (Castillo & Comstock,  2007 ). About 2 percent of seniors, again mostly boys, have taken anabolic steroids or a related substance, androstenedione—powerful prescription medications that boost muscle mass and strength (Johnston et al.,  2012 ). Teenagers usually obtain steroids illegally, ignoring side effects, which range from acne, excess body hair, and high blood pressure to mood swings, aggressive behavior, and damage to the liver, circulatory system, and reproductive organs (Casavant et al.,  2007 ). Coaches and health professionals should inform teenagers of the dangers of these performance-enhancing substances.

In 1972, the U.S. federal government required schools receiving public funds to provide equal opportunities for males and females in all educational programs, including athletics. Since then, high school girls’ sports participation has increased, but it still falls far short of boys’. According to a recent survey of all 50 U.S. state high school athletic associations, 41 percent of sports participants are girls, 59 percent boys (National Federation of State High School Associations,  2012 ). In  Chapter 9 , we saw that girls get less encouragement and recognition for athletic achievement, a pattern that starts early and persists into the teenage years (see  page 296 ).

Furthermore, when researchers followed a large, representative sample of U.S. youths from ages 9 to 15, physical activity declined by about 40 minutes per day each year until, at age 15, less than one-third met the U.S. government recommendation of at least 60 minutes of moderate to strenuous physical activity per day (see  Figure 11.2 ) (Nader et al.,  2008 ). In high school, only 57 percent of U.S. boys and 47 percent of girls are enrolled in any physical education, with 31 percent of all students experiencing a daily physical education class (U.S. Department of Health and Human Services,  2012f ).

Besides improving motor performance, sports and exercise influence cognitive and social development. Interschool and intramural athletics provide important lessons in teamwork, problem solving, assertiveness, and competition. And regular, sustained physical activity—which required physical education can ensure—is associated with lasting physical and mental health benefits and enjoyment of sports and exercise (Brand et al.,  2010 ). In one study, participating in team or individual sports at age 14 at least once a week for girls and twice a week for boys predicted high physical activity rates at age 31. Endurance sports, such as running and cycling—activities that do not require expensive equipment or special facilities—were especially likely to continue into adulthood (Tammelin et al.,  2003 ). And adolescent exertion during exercise, defined as sweating and breathing heavily, is one of the best predictors of adult physical exercise, perhaps because it fosters high physical self-efficacy—belief in one’s ability to sustain an exercise program (Motl et al.,  2002 ; Telama et al.,  2005 ).

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High school girls’ participation in sports has increased but still falls far short of boys’. Yet athletic participation yields many benefits—not just gains in motor skills but important lessons in teamwork, problem solving, assertiveness, and competition.

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FIGURE 11.2 Decline in physical activity from ages 9 to 15 among U.S. boys and girls.

In a large representative sample of youths followed over six years, time spent exercising dropped sharply until, at age 15, most youths did not meet government recommendations of at least 60 minutes of moderate to vigorous physical activity per day. At all ages, boys spent more time exercising than girls.

(Adapted from Nader et al., 2008.)

Sexual Maturation

Accompanying rapid body growth are changes in physical features related to sexual functioning. Some, called  primary sexual characteristics , involve the reproductive organs (ovaries, uterus, and vagina in females; penis, scrotum, and testes in males). Others, called  secondary sexual characteristics , are visible on the outside of the body and serve as additional signs of sexual maturity (for example, breast development in females and the appearance of underarm and pubic hair in both sexes). As  Table 11.1  on  page 366  shows, these characteristics develop in a fairly standard sequence, although the ages at which each begins and is completed vary greatly. Typically, pubertal development takes about four years, but some adolescents complete it in two years, whereas others take five to six years.

Sexual Maturation in Girls.

Female puberty usually begins with the budding of the breasts and the growth spurt.  Menarche , or first menstruation, typically occurs around age 12½ for North American girls, 13 for Western Europeans. But the age range is wide, from 10½ to 15½ years. Following menarche, breast and pubic hair growth are completed, and underarm hair appears.

Notice in  Table 11.1  that nature delays sexual maturity until the girl’s body is large enough for childbearing; menarche takes place after the peak of the height spurt. As an extra measure of security, for 12 to 18 months following menarche, the menstrual cycle often occurs without the release of an ovum from the ovaries (Archibald, Graber, & Brooks-Gunn,  2006 ; Bogin,  2001 ). But this temporary period of sterility does not occur in all girls, and it does not provide reliable protection against pregnancy.

TABLE 11.1 Pubertal Development in North American Girls and Boys

GIRLS   AVERAGE AGE ATTAINED AGE RANGE BOYS   AVERAGE AGE ATTAINED AGE RANGE
Breasts begin to “bud” 10 8–13 Testes begin to enlarge 11.5 9.5–13.5
Height spurt begins 10 8–13 Pubic hair appears 12 10–15
Pubic hair appears 10.5 8–14 Penis begins to enlarge image10 12 10.5–14.5
Peak strength spurt image11 11.6 9.5–14 Height spurt begins 12.5 10.5–16
Peak height spurt 11.7 10–13.5 Spermarche (first ejaculation) occurs 13.5 12–16
Menarche (first menstruation) occurs 12.5 10.5–14 Peak height spurt 14 12.5–15.5
Peak weight spurt 12.7 10–14 Peak weight spurt 14 12.5–15.5
Adult stature reached 13 10–16 Facial hair begins to grow 14 12.5–15.5
Pubic hair growth completed 14.5 14–15 Voice begins to deepen 14 12.5–15.5
Breast growth completed 15 10–17 Penis and testes growth completed 14.5 12.5–16
Peak strength spurt 15.3 13–17
Adult stature reached 15.5 13.5–17.5
Pubic hair growth completed 15.5 14–17

Sources: Chumlea et al., 2003; Herman-Giddens, 2006; Rogol, Roemmich, & Clark, 2002; Rubin et al., 2009; Wu, Mendola, & Buck, 2002.

Photos:(left) © Laura Dwight Photography; (right) Rob Melnychuk/Taxi/Getty Images

Sexual Maturation in Boys.

The first sign of puberty in boys is the enlargement of the testes (glands that manufacture sperm), accompanied by changes in the texture and color of the scrotum. Pubic hair emerges soon after, about the same time the penis begins to enlarge (Rogol, Roemmich, & Clark,  2002 ).

As  Table 11.1  reveals, the growth spurt occurs much later in the sequence of pubertal events for boys than for girls. When it reaches its peak around age 14, enlargement of the testes and penis is nearly complete, and underarm hair appears. So do facial and body hair, which increase gradually for several years. Another landmark of male physical maturity is the deepening of the voice as the larynx enlarges and the vocal cords lengthen. (Girls’ voices also deepen slightly.) Voice change usually takes place at the peak of the male growth spurt and is often not complete until puberty is over (Archibald, Graber, & Brooks-Gunn,  2006 ).

While the penis is growing, the prostate gland and seminal vesicles (which together produce semen, the fluid containing sperm) enlarge. Then, around age 13½,  spermarche , or first ejaculation, occurs (Rogol, Roemmich, & Clark,  2002 ). For a while, the semen contains few living sperm. So, like girls, boys have an initial period of reduced fertility.

Individual Differences in Pubertal Growth

Heredity contributes substantially to the timing of pubertal changes. Identical twins are more similar than fraternal twins in attainment of most pubertal milestones (Eaves et al.,  2004 ; Mustanski et al.,  2004 ). Nutrition and exercise also make a difference. In females, a sharp rise in body weight and fat may trigger sexual maturation. Fat cells release a protein called leptin, which is believed to signal the brain that the girl’s energy stores are sufficient for puberty—a likely reason that breast and pubic hair growth and menarche occur earlier for heavier and, especially, obese girls. In contrast, girls who begin rigorous athletic training at an early age or who eat very little (both of which reduce the percentage of body fat) usually experience later puberty (Kaplowitz,  2007 ; Lee et al.,  2007 ; Rubin et al.,  2009 ). Few studies, however, report a link between body fat and puberty in boys.

Variations in pubertal growth also exist among regions of the world and among SES and ethnic groups. Physical health plays a major role. In poverty-stricken regions where malnutrition and infectious disease are common, menarche is greatly delayed, occurring as late as age 14 to 16 in many parts of Africa. Within developing countries, girls from higher-income families reach menarche 6 to 18 months earlier than those living in economically disadvantaged homes (Parent et al.,  2003 ).

But in industrialized nations where food is abundant, the joint roles of heredity and environment in pubertal growth are apparent. For example, breast and pubic hair growth begin, on average, around age 9 in African-American girls—a year earlier than in Caucasian-American girls. And African-American girls reach menarche about six months earlier, around age 12. Although widespread overweight and obesity in the black population contribute, a genetically influenced faster rate of physical maturation is also involved. Black girls usually reach menarche before white girls of the same age and body weight (Chumlea et al.,  2003 ; Herman-Giddens,  2006 ; Hillard,  2008 ).

Early family experiences may also affect pubertal timing. One theory suggests that humans have evolved to be sensitive to the emotional quality of their childhood environments. When children’s safety and security are at risk, it is adaptive for them to reproduce early. Research indicates that girls and (less consistently) boys with a history of family conflict, harsh parenting, or parental separation tend to reach puberty early. In contrast, those with warm, stable family ties reach puberty relatively late (Belsky et al.,  2007 ; Bogaert,  2005 ; Ellis,  2004 ; Ellis & Essex,  2007 ; Mustanski et al.,  2004 ; Tremblay & Frigon,  2005 ). Critics offer an alternative explanation—that mothers who reached puberty early are more likely to bear children earlier, which increases the likelihood of marital conflict and separation (Mendle et al.,  2006 ). But two longitudinal studies confirm the former chain of influence among girls: from adverse family environments in childhood to earlier pubertal timing to increased sexual risk taking (Belsky et al.,  2010 ; James et al.,  2012 ).

In the research we have considered, threats to emotional health accelerate puberty, whereas threats to physical health delay it. A  secular trend , or generational change, in pubertal timing lends added support to the role of physical well-being in pubertal development. In industrialized nations, age of menarche declined steadily—by about 3 to 4 months per decade—from 1900 to 1970, a period in which nutrition, health care, sanitation, and control of infectious disease improved greatly. Boys, too, have reached puberty earlier in recent decades (Herman-Giddens et al.,  2012 ). And as developing nations make socioeconomic progress, they also show secular gains (Ji & Chen,  2008 ).

In the United States and a few European countries, soaring rates of overweight and obesity are responsible for a modest, continuing trend toward earlier menarche (Kaplowitz,  2006 ; Parent et al.,  2003 ). A worrisome consequence is that girls who reach sexual maturity at age 10 or 11 will feel pressure to act much older than they are. As we will see shortly, early-maturing girls are at risk for unfavorable peer involvements, including sexual activity.

Brain Development

The physical transformations of adolescence include major changes in the brain. Brain-imaging research reveals continued pruning of unused synapses in the cerebral cortex, especially in the prefrontal cortex. In addition, linkages between the two cerebral hemispheres through the corpus callosum, and between the prefrontal cortex and other areas in the cerebral cortex and the inner brain (including the amygdala), expand, myelinate, and attain rapid communication. As a result, the prefrontal cortex becomes a more effective “executive”—overseeing and managing the integrated functioning of various areas, yielding more complex, flexible, and adaptive thinking and behavior (Blakemore & Choudhury,  2006 ; Lenroot & Giedd,  2006 ). Consequently, adolescents gain in diverse cognitive skills, including processing speed and executive function.

But these advances occur gradually over the teenage years. fMRI evidence reveals that adolescents recruit the prefrontal cortex’s network of connections with other brain areas less effectively than adults do. Because the prefrontal cognitive-control network still requires fine-tuning, teenagers’ performance on executive function tasks requiring inhibition, planning, and future orientation (rejecting a smaller immediate reward in favor of a larger delayed reward) is not yet fully mature (McClure et al.,  2004 ; Smith, Xiao, & Bechara,  2012 ; Steinberg et al.,  2009 ).

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In adolescence, changes in the brain’s emotional/social network outpace development of the cognitive-control network. As a result, teenagers do not yet have the capacity to control their powerful drive for new—and sometimes risky—experiences.

Adding to these self-regulation difficulties are changes in the brain’s emotional/social network. In humans and other mammals, neurons become more responsive to excitatory neurotransmitters during puberty. As a result, adolescents react more strongly to stressful events and experience pleasurable stimuli more intensely. But because the cognitive control network is not yet functioning optimally, most teenagers find it hard to manage these powerful feelings (Ernst & Spear,  2009 ; Steinberg et al.,  2008 ). This imbalance contributes to teenagers’ drive for novel experiences, including drug taking, reckless driving, unprotected sex, and delinquent activity (Pharo et al.,  2011 ). In a longitudinal study of a nationally representative sample of 7,600 U.S. youths, researchers tracked changes in self-reported impulsivity and sensation seeking between ages 12 and 24 (Harden & Tucker-Drob,  2011 ). As  Figure 11.3  on  page 368  shows, impulsivity declined steadily with age—evidence for gradual improvement of the cognitive-control network. But sensation seeking increased from 12 to 16, followed by a more gradual decline through age 24, reflecting the challenge posed by the emotional/social network.

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FIGURE 11.3 Development of impulsivity and sensation seeking from 12 to 24 years.

In this longitudinal study of a large, nationally representative U.S. sample, impulsivity declined steadily, while sensation seeking increased in early adolescence and then diminished more gradually. Findings confirm the challenge posed by the emotional/social network to the cognitive control network.

(From K. P. Harden and E. M. Tucker-Drob, 2011, “Individual Differences in the Development of Sensation Seeking and Impulsivity During Adolescence: Further Evidence for a Dual Systems Model,” Developmental Psychology, 47, p. 742. Copyright © 2011 by the American Psychological Association. Adapted with permission of the American Psychological Association.)

In sum, changes in the adolescent brain’s emotional/social network outpace development of the cognitive-control network. Only over time are young people able to effectively manage their emotions and reward-seeking behavior. Of course, wide individual differences exist in the extent to which teenagers manifest this rise in risk-taking in the form of careless, dangerous acts—some not at all, and others extremely so (Pharo et al.,  2011 ). But transformations in the adolescent brain enhance our understanding of both the cognitive advances and the worrisome behaviors of this period, along with teenagers’ need for adult patience, oversight, and guidance.

Changing States of Arousal

At puberty, revisions occur in the way the brain regulates the timing of sleep, perhaps because of increased neural sensitivity to evening light. As a result, adolescents go to bed much later than they did as children. Yet they need almost as much sleep as they did in middle childhood—about nine hours. When the school day begins early, their sleep needs are not satisfied.

This sleep “phase delay” strengthens with pubertal growth. But today’s teenagers—who often have evening social activities, part-time jobs, and bedrooms equipped with TVs, computers, and phones—get much less sleep than teenagers of previous generations (Carskadon et al.,  2002 ; Jenni, Achermann, & Carskadon,  2005 ). Sleep-deprived adolescents display declines in executive function, performing especially poorly on cognitive tasks during morning hours. And they are more likely to achieve less well in school, suffer from anxiety and depressed mood, and engage in high-risk behaviors (Dahl & Lewin,  2002 ; Hansen et al.,  2005 ; Talbot et al.,  2010 ). Sleep rebound on weekends sustains the pattern by leading to difficulty falling asleep on subsequent evenings. Later school start times ease but do not eliminate sleep loss. Educating teenagers about the importance of sleep is vital.

image14 The Psychological Impact of Pubertal Events

TAKE A MOMENT…  Think back to your late elementary and middle school days. As you reached puberty, how did your feelings about yourself and your relationships with others change? Research reveals that pubertal events affect adolescents’ self-image, mood, and interaction with parents and peers. Some outcomes are a response to dramatic physical change, whenever it occurs. Others have to do with pubertal timing.

Reactions to Pubertal Changes

Two generations ago, menarche was often traumatic. Today, girls commonly react with “surprise,” undoubtedly due to the sudden onset of the event. Otherwise, they typically report a mixture of positive and negative emotions (DeRose & Brooks-Gunn,  2006 ). Yet wide individual differences exist that depend on prior knowledge and support from family members, which in turn are influenced by cultural attitudes toward puberty and sexuality.

For girls who have no advance information, menarche can be shocking and disturbing. Unlike 50 to 60 years ago, today few girls are uninformed, a shift that is probably due to parents’ greater willingness to discuss sexual matters and to the spread of health education classes (Omar, McElderry, & Zakharia,  2003 ). Almost all girls get some information from their mothers. And some evidence suggests that compared with Caucasian-American families, African-American families may better prepare girls for menarche, treat it as an important milestone, and express less conflict over girls reaching sexual maturity—factors that lead African-American girls to react more favorably (Martin,  1996 ).

Like girls’ reactions to menarche, boys’ responses to spermarche reflect mixed feelings. Virtually all boys know about ejaculation ahead of time, but many say that no one spoke to them before or during puberty about physical changes (Omar, McElderry, & Zakharia,  2003 ). Usually they get their information from reading material or websites. Even boys who had advance information often say that their first ejaculation occurred earlier than they expected and that they were unprepared for it. As with girls, boys who feel better prepared tend to react more positively (Stein & Reiser,  1994 ). But whereas almost all girls eventually tell a friend that they are menstruating, far fewer boys tell anyone about spermarche (DeRose & Brooks-Gunn,  2006 ; Downs & Fuller,  1991 ). Overall, boys get much less social support than girls for the physical changes of puberty. They might benefit, especially, from opportunities to ask questions and discuss feelings with a sympathetic parent or health professional.

Many tribal and village societies celebrate the onset of puberty with an initiation ceremony, a ritualized announcement to the community that marks an important change in privilege and responsibility. Consequently, young people know that reaching puberty is valued in their culture. In contrast, Western societies grant little formal recognition to movement from childhood to adolescence or from adolescence to adulthood. Ceremonies such as the Jewish bar or bat mitzvah and the quinceañera in Hispanic communities (celebrating a 15-year-old girl’s sexual maturity and marriage availability), resemble initiation ceremonies, but only within the ethnic or religious subculture. They do not mark a significant change in social status in the larger society.

Instead, Western adolescents are granted partial adult status at many different ages—for example, an age for starting employment, for driving, for leaving high school, for voting, and for drinking. And in some contexts (at home and at school), they may still be regarded as children. The absence of a widely accepted marker of physical and social maturity makes the process of becoming an adult more confusing.

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This 13-year-old’s bat mitzvah ceremony recognizes her as an adult with moral and religious responsibilities in the Jewish community. In the larger society, however, she will experience no change in status.

Pubertal Change, Emotion, and Social Behavior

A common belief is that puberty has something to do with adolescent moodiness and the desire for greater physical and psychological separation from parents. Let’s see what research says about these relationships.

Adolescent Moodiness.

Higher pubertal hormone levels are linked to greater moodiness, but only modestly so (Buchanan, Eccles, & Becker,  1992 ; Graber, Brooks-Gunn, & Warren,  2006 ). What other factors might contribute? In several studies, the moods of children, adolescents, and adults were monitored by having them carry electronic pagers. Over a one-week period, they were beeped at random intervals and asked to write down what they were doing, whom they were with, and how they felt.

As expected, adolescents reported less favorable moods than school-age children and adults (Larson et al.,  2002 ; Larson & Lampman-Petraitis,  1989 ). But negative moods were linked to a greater number of negative life events, such as difficulty getting along with parents, disciplinary actions at school, and breaking up with a boyfriend or girlfriend. Negative events increased steadily from childhood to adolescence, and teenagers also seemed to react to them with greater emotion than children (Larson & Ham,  1993 ). (Recall that stress reactivity is heightened by changes in the brain’s emotional/social network during puberty.)

Compared with the moods of older adolescents and adults, those of younger adolescents (ages 12 to 16) were less stable, often shifting between cheerful and sad. These mood swings were strongly related to situational changes. High points of adolescents’ days were times spent with peers and in self-chosen leisure activities. Low points tended to occur in adult-structured settings—class, job, and religious services. Furthermore, emotional highs coincided with Friday and Saturday evenings, especially in high school. Going out with friends and romantic partners increases so dramatically during adolescence that it becomes a “cultural script” for what is supposed to happen (Larson & Richards,  1998 ). Consequently, teenagers who spend weekend evenings at home often feel profoundly lonely.

Fortunately, frequent reports of negative mood level off in late adolescence (Natsuaki, Biehl, & Ge,  2009 ). And overall, teenagers with supportive family and peer relationships more often report positive and less often negative moods than their agemates with few social supports (Weinstein et al.,  2006 ). In contrast, poorly adjusted young people—with low self-esteem, conduct difficulties, or delinquency—tend to react with stronger negative emotion to unpleasant daily experiences, perhaps compounding their adjustment problems (Schneiders et al.,  2006 ).

Parent–Child Relationships.

Sabrina’s father noticed that as his children entered adolescence, they kept their bedroom doors closed, resisted spending time with the family, and became more argumentative. Sabrina and her mother squabbled over Sabrina’s messy room (“It’s my room, Mom. You don’t have to live in it!”). And Sabrina protested the family’s regular weekend visit to Aunt Gina’s (“Why do I have to go every week?”). Research in cultures as diverse as the United States and Turkey shows that puberty is related to a rise in intensity of parent–child conflict, which persists into middle adolescence (Gure, Ucanok, & Sayil,  2006 ; Laursen, Coy, & Collins,  1998 ; McGue et al.,  2005 ).

Why should a youngster’s more adultlike appearance trigger these disputes? The association may have adaptive value. Among nonhuman primates, the young typically leave the family group around the time of puberty. The same is true in many nonindustrialized cultures (Caine,  1986 ; Schlegel & Barry,  1991 ). Departure of young people discourages sexual relations between close blood relatives. But adolescents in industrialized nations, who are still economically dependent on parents, cannot leave the family. Consequently, a substitute seems to have emerged: psychological distancing.

As children become physically mature, they demand to be treated in adultlike ways. And as we will see, adolescents’ new powers of reasoning may also contribute to a rise in family tensions. Parent–adolescent disagreements focus largely on everyday matters such as driving, dating partners, and curfews (Adams & Laursen,  2001 ). But beneath these disputes lie serious concerns: parental efforts to protect teenagers from substance use, auto accidents, and early sex. The larger the gap between parents’ and adolescents’ views of teenagers’ readiness for new responsibilities, the more they quarrel (Deković, Noom, & Meeus,  1997 ).

Parent–daughter conflict tends to be more intense than conflict with sons, perhaps because parents place more restrictions on girls (Allison & Schultz,  2004 ). But most disputes are mild and diminish by late adolescence. Parents and teenagers display both conflict and affection, and they usually agree on important values, such as honesty and the importance of education. And as the teenage years conclude, parent–adolescent interactions are less hierarchical, setting the stage for mutually supportive relationships in adulthood (Laursen & Collins,  2009 ).

LOOK AND LISTEN

Interview several parents and/or their 12- to 14-year-olds about recent changes in parent–child relationships. Has conflict increased? Over what topics?

Pubertal Timing

“All our children were early maturers,” said Franca during the parents’ discussion group. “The three boys were tall by age 12 or 13, but it was easier for them. They felt big and important. Sabrina was skinny as a little girl, but now she says she is too fat and needs to diet. She thinks about boys and doesn’t concentrate on her schoolwork.”

Findings of several studies match the experiences of Sabrina and her brothers. Both adults and peers viewed early-maturing boys as relaxed, independent, self-confident, and physically attractive. Popular with agemates, they tended to hold leadership positions in school and to be athletic stars. In contrast, late-maturing boys expressed more anxiety and depressed mood than their on-time counterparts (Brooks-Gunn,  1988 ; Huddleston & Ge,  2003 ). But early-maturing boys, though viewed as well-adjusted, reported more psychological stress, depressed mood, and problem behaviors (sexual activity, smoking, drinking, aggression, delinquency) than both their on-time and later-maturing agemates (Ge, Conger, & Elder,  2001 ; Natsuaki, Biehl, & Ge,  2009 ; Susman & Dorn,  2009 ).

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African-American early-maturing girls are more likely to report a positive body image than their Caucasian counterparts. Perhaps because their families and friends tend to welcome menarche, they may escape the adjustment difficulties commonly associated with early pubertal timing.

In contrast, early-maturing girls were unpopular, withdrawn, lacking in self-confidence, anxious (especially about others’ negative evaluations), and prone to depression, and they held few leadership positions (Blumenthal et al.,  2011 ; Ge, Conger, & Elder,  1996 ; Graber, Brooks-Gunn, & Warren,  2006 ; Jones & Mussen,  1958 ). And like early-maturing boys, they were more involved in deviant behavior (smoking, drinking, sexual activity) (Caspi et al.,  1993 ; Dick et al.,  2000 ; Ge et al.,  2006 ). In contrast, their later-maturing counterparts were regarded as physically attractive, lively, sociable, and leaders at school. In one study of several hundred eighth graders, however, negative effects were not evident among early-maturing African-American girls, whose families—and perhaps friends as well—tend to be more unconditionally welcoming of menarche (see  page 365 ) (Michael & Eccles,  2003 ).

Two factors largely account for these trends: (1) how closely the adolescent’s body matches cultural ideals of physical attractiveness, and (2) how well young people fit in physically with their peers.

The Role of Physical Attractiveness.

TAKE A MOMENT…  Flip through your favorite popular magazine. You will see evidence of our society’s view of an attractive female as thin and long-legged and of a good-looking male as tall, broad-shouldered, and muscular. The female image is a girlish shape that favors the late developer. The male image fits the early-maturing boy.

Consistent with these preferences, early-maturing Caucasian girls tend to report a less positive  body image —conception of and attitude toward their physical appearance—than their on-time and late-maturing agemates. Compared with African-American and Hispanic girls, Caucasian girls are more likely to have internalized the cultural ideal of female attractiveness. Most want to be thinner (Rosen,  2003 ; Stice, Presnell, & Bear-man,  2001 ; Williams & Currie,  2000 ). Although boys are less consistent, early, rapid maturers are more likely to be satisfied with their physical characteristics (Alsaker,  1995 ; Sinkkonen, Anttila, & Siimes,  1998 ).

Body image is a strong predictor of young people’s self-esteem (Harter,  2006 ). But the negative effects of pubertal timing on body image and—as we will see next—emotional adjustment are greatly amplified when accompanied by other stressors (Stice,  2003 ).

The Importance of Fitting in with Peers.

Physical status in relation to peers also explains differences in adjustment between early and late maturers. From this perspective, early-maturing girls and late-maturing boys have difficulty because they fall at the extremes of physical development and feel out of place when with their agemates. Not surprisingly, adolescents feel most comfortable with peers who match their own level of biological maturity (Stattin & Magnusson,  1990 ).

Because few agemates of the same pubertal status are available, early-maturing adolescents of both sexes seek out older companions, who often encourage them into activities they are not ready to handle emotionally. And hormonal influences on the brain’s emotional/social network are stronger for early maturers, further magnifying their receptiveness to sexual activity, drug and alcohol use, and delinquent acts (Ge et al.,  2002 ; Steinberg,  2008 ). Perhaps as a result, early maturers of both sexes more often report feeling stressed and show declines in academic performance (Mendle, Turkheimer, & Emery,  2007 ; Natsuaki, Biehl, & Ge,  2009 ).

At the same time, the young person’s context greatly increases the likelihood that early pubertal timing will lead to negative outcomes. Early maturers in economically disadvantaged neighborhoods are especially vulnerable to establishing ties with deviant peers, which heightens their defiant, hostile behavior. And because families in such neighborhoods tend to be exposed to chronic, severe stressors and to have few social supports, these early maturers are also more likely to experience harsh, inconsistent parenting, which, in turn, predicts both deviant peer associations and antisocial behavior (Ge et al.,  2002  2011 ).

Long-Term Consequences.

Do the effects of pubertal timing last? Follow-ups reveal that early-maturing girls, especially, are prone to lasting difficulties. In one study, depression subsided by age 13 in early-maturing boys but tended to persist in early-maturing girls (Ge et al.,  2003 ). In another study, which followed young people from ages 14 to 24, early-maturing boys again showed good adjustment. But early-maturing girls reported poorer-quality relationships with family and friends, smaller social networks, and lower life satisfaction into early adulthood than their on-time counterparts (Graber et al.,  2004 ).

Recall that childhood family conflict and harsh parenting are linked to earlier pubertal timing, more so for girls than for boys (see  page 367 ). Perhaps many early-maturing girls enter adolescence with emotional and social difficulties. As the stresses of puberty interfere with school performance and lead to unfavorable peer pressures, poor adjustment extends and deepens (Graber,  2003 ). Clearly, interventions that target at-risk early-maturing youths are needed. These include educating parents and teachers and providing adolescents with counseling and social supports so they will be better prepared to handle the emotional and social challenges of this transition.

ASK YOURSELF

REVIEW Summarize the impact of pubertal timing on adolescent development.

CONNECT How might adolescent moodiness contribute to psychological distancing between parents and adolescents? (Hint: Think about bidirectional influences in parent–child relationships.)

APPLY As a school-age child, Chloe enjoyed leisure activities with her parents. Now, at age 14, she spends hours in her room and resists going on weekend family excursions. Explain Chloe’s behavior.

REFLECT Recall your own reactions to the physical changes of puberty. Are they consistent with research findings? Explain.

image17 Health Issues

The arrival of puberty brings new health issues related to the young person’s efforts to meet physical and psychological needs. As adolescents attain greater autonomy, their personal decision making becomes important, in health as well as other areas. Yet none of the health concerns we are about to discuss can be traced to a single cause. Rather, biological, psychological, family, peer, and cultural factors jointly contribute.

Nutritional Needs

When their sons reached puberty, Franca and Antonio reported a “vacuum cleaner effect” in the kitchen as the boys routinely emptied the refrigerator. Rapid body growth leads to a dramatic increase in nutritional requirements, at a time when the diets of many young people are the poorest. Of all age groups, adolescents are the most likely to skip breakfast (a practice linked to obesity), eat on the run, and consume empty calories (Ritchie et al.,  2007 ; Striegel-Moore & Franko,  2006 ). Fast-food restaurants, where teenagers often gather, have begun to offer some healthy menu options. But adolescents need guidance in choosing these alternatives. Eating fast food and school purchases from snack bars and vending machines is strongly associated with consumption of soft drinks and foods high in fat and sugar, indicating that teenagers often make unhealthy food choices (Bowman et al.,  2004 ; Kubik et al.,  2003 ).

The most common nutritional problem of adolescence is iron deficiency. Iron requirements increase to a maximum during the growth spurt and remain high among girls because of iron loss during menstruation. A tired, irritable teenager may be suffering from anemia rather than unhappiness and should have a medical checkup. Most adolescents do not get enough calcium and are also deficient in riboflavin (vitamin B2) and magnesium, both of which support metabolism (Cavadini, Siega-Riz, & Popkin,  2000 ).

Frequency of family meals is strongly associated with greater intake of fruits, vegetables, grains, and calcium-rich foods and reduced soft drink and fast-food consumption (Burgess-Champoux et al.,  2009 ; Fiese & Schwartz,  2008 ). But compared to families with younger children, those with adolescents eat fewer meals together. In addition to their other benefits (see  page 63  in  Chapter 2  and  page 291  in  Chapter 9 ), family meals can greatly improve teenagers’ diets.

Adolescents—especially girls concerned about their weight—tend to be attracted to fad diets. Unfortunately, most are too limited in nutrients and calories to be healthy for fast-growing, active teenagers (Donatelle,  2012 ). Parents should encourage young people to consult a doctor or dietitian before trying any special diet.

Eating Disorders

Concerned about her daughter’s desire to lose weight, Franca explained to Sabrina that she was really quite average in build for an adolescent girl and reminded her that her Italian ancestors had considered a plump female body more beautiful than a thin one. Girls who reach puberty early, who are very dissatisfied with their body image, and who grow up in homes where concern with weight and thinness is high are at risk for eating problems. Severe dieting is the strongest predictor of the onset of an eating disorder in adolescence (Lock & Kirz,  2008 ). The two most serious are anorexia nervosa and bulimia nervosa.

Anorexia Nervosa.

Anorexia nervosa  is a tragic eating disorder in which young people starve themselves because of a compulsive fear of getting fat. It affects about 1 percent of North American and Western European teenage girls. During the past half-century, cases have increased sharply, fueled by cultural admiration of female thinness. Anorexia nervosa is equally common in all SES groups, but Asian-American, Caucasian-American, and Hispanic girls are at greater risk than African-American girls, who tend to be more satisfied with their size and shape (Granillo, Jones-Rodriguez, & Carvajal,  2005 ; Ozer & Irwin,  2009 ; Steinhausen,  2006 ). Boys account for 10 to 15 percent of anorexia cases; about half of these are gay or bisexual young people who are uncomfortable with a strong, muscular appearance (Raevuori et al.,  2009 ; Robb & Dadson,  2002 ).

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Aiva, a 16-year-old anorexia nervosa patient, is shown at left on the day she entered treatment—weighing just 77 pounds—and, at right, after a 10-week treatment program. Less than 50 percent of young people with anorexia recover fully.

Individuals with anorexia have an extremely distorted body image. Even after they have become severely underweight, they see themselves as too heavy. Most go on self-imposed diets so strict that they struggle to avoid eating in response to hunger. To enhance weight loss, they exercise strenuously.

In their attempt to reach “perfect” slimness, individuals with anorexia lose between 25 and 50 percent of their body weight. Because a normal menstrual cycle requires about 15 percent body fat, either menarche does not occur or menstrual periods stop. Malnutrition causes pale skin, brittle discolored nails, fine dark hairs all over the body, and extreme sensitivity to cold. If it continues, the heart muscle can shrink, the kidneys can fail, and irreversible brain damage and loss of bone mass can occur. About 6 percent of individuals with anorexia die of the disorder, as a result of either physical complications or suicide (Katzman,  2005 ).

Forces within the person, the family, and the larger culture give rise to anorexia nervosa. Identical twins share the disorder more often than fraternal twins, indicating a genetic influence. Abnormalities in neurotransmitters in the brain, linked to anxiety and impulse control, may make some individuals more susceptible (Kaye,  2008 ; Lock & Kirz,  2008 ). Many young people with anorexia have unrealistically high standards for their own behavior and performance, are emotionally inhibited, and avoid intimate ties outside the family. Consequently, they are often excellent students who are responsible and well-behaved. But as we have also seen, the societal image of “thin is beautiful” contributes to the poor body image of many girls—especially early-maturing girls, who are at greatest risk for anorexia nervosa (Hogan & Strasburger,  2008 ).

In addition, parent–adolescent interactions reveal problems related to adolescent autonomy. Often the mothers of these girls have high expectations for physical appearance, achievement, and social acceptance and are overprotective and controlling. Fathers tend to be emotionally distant. These parental attributes may contribute to affected girls’ persistent anxiety and fierce pursuit of perfection in achievement, respectable behavior, and thinness (Kaye,  2008 ). Nevertheless, it remains unclear whether maladaptive parent–child relationships precede the disorder, emerge in response to it, or both.

Because individuals with anorexia typically deny or minimize the seriousness of their disorder, treating it is difficult (Couturier & Lock,  2006 ). Hospitalization is often necessary to prevent life-threatening malnutrition. The most successful treatment is family therapy plus medication to reduce anxiety and neurotransmitter imbalances (Robin & Le Grange,  2010 ; Treasure & Schmidt,  2005 ). Still, less than 50 percent of young people with anorexia recover fully. For many, eating problems continue in less extreme form. About 10 percent show signs of a less severe, but nevertheless debilitating, disorder: bulimia nervosa.

Bulimia Nervosa.

In  bulimia nervosa , young people (again, mainly girls, but gay and bisexual boys are also vulnerable) engage in strict dieting and excessive exercise accompanied by binge eating, often followed by deliberate vomiting and purging with laxatives (Herzog, Eddy, & Beresin,  2006 ; Wichstrøm,  2006 ). Bulimia typically appears in late adolescence and is more common than anorexia nervosa, affecting about 2 to 4 percent of teenage girls, only 5 percent of whom previously suffered from anorexia.

Twin studies show that bulimia, like anorexia, is influenced by heredity (Klump, Kaye, & Strober,  2001 ). Overweight and early menarche increase the risk. Some adolescents with bulimia, like those with anorexia, are perfectionists. But most are impulsive, sensation-seeking young people who lack self-control in many areas, engaging in petty shoplifting, alcohol abuse, and other risky behaviors (Kaye,  2008 ). And although girls with bulimia, like those with anorexia, are pathologically anxious about gaining weight, they may have experienced their parents as disengaged and emotionally unavailable rather than controlling (Fairburn & Harrison,  2003 ).

In contrast to young people with anorexia, those with bulimia usually feel depressed and guilty about their abnormal eating habits and desperately want help. As a result, bulimia is usually easier to treat than anorexia, through support groups, nutrition education, training in changing eating habits, and anti-anxiety, antidepressant, and appetite-control medication (Hay & Bacaltchuk,  2004 ).

Sexuality

Sabrina’s 16-year-old brother Louis and his girlfriend Cassie hadn’t planned to have intercourse—it “just happened.” But before and after, a lot of things passed through their minds. After they had dated for three months, Cassie began to wonder, “Will Louis think I’m normal if I don’t have sex with him? If he wants to and I say no, will I lose him?” Both young people knew their parents wouldn’t approve. In fact, when Franca and Antonio noticed how attached Louis was to Cassie, they talked to him about the importance of waiting and the dangers of pregnancy. But that Friday evening, Louis and Cassie’s feelings for each other seemed overwhelming. “If I don’t make a move,” Louis thought, “will she think I’m a wimp?”

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Cultural attitudes will profoundly affect the way these young teenagers, who are just beginning to explore their sexual attraction to each other, learn to manage sexuality in social relationships.

With the arrival of puberty, hormonal changes—in particular, the production of androgens in young people of both sexes—lead to an increase in sex drive (Halpern, Udry, & Suchindran,  1997 ). In response, adolescents become very concerned about managing sexuality in social relationships. New cognitive capacities involving perspective taking and self-reflection affect their efforts to do so. Yet like the eating behaviors we have just discussed, adolescent sexuality is heavily influenced by the young person’s social context.

The Impact of Culture.

TAKE A MOMENT…  When did you first learn the “facts of life”—and how? Was sex discussed openly in your family, or was it treated with secrecy? Exposure to sex, education about it, and efforts to limit the sexual curiosity of children and adolescents vary widely around the world.

Despite the prevailing image of sexually free adolescents, sexual attitudes in North America are relatively restrictive. Typically, parents provide little or no information about sex, discourage sex play, and rarely talk about sex in children’s presence. When young people become interested in sex, only about half report getting information from parents about intercourse, pregnancy prevention, and sexually transmitted disease. Many parents avoid meaningful discussions about sex out of fear of embarrassment or concern that the adolescent will not take them seriously (Wilson et al.,  2010 ). Yet warm, open give-and-take is associated with teenagers’ adoption of parents’ views and with reduced sexual risk taking (Jaccard, Dodge, & Dittus,  2003 ; Usher-Seriki, Bynum, & Callands,  2008 ).

Adolescents who do not get information about sex from their parents are likely to learn from friends, books, magazines, movies, TV, and the Internet (Jaccard, Dodge, & Dittus,  2002 ; Sutton et al.,  2002 ). On prime-time TV shows, which adolescents watch more than other TV offerings, 80 percent of programs contain sexual content. Most depict partners as spontaneous and passionate, taking no steps to avoid pregnancy or sexually transmitted disease, and experiencing no negative consequences (Roberts, Henriksen, & Foehr,  2004 ). In several studies, teenagers’ media exposure to sexual content predicted current sexual activity, intentions to be sexually active in the future, and subsequent sexual activity, pregnancies, and sexual harassment behaviors (offensive name-calling or touching, pressuring a peer for a date) even after many other relevant factors were controlled (Brown & L’Engle,  2009 ; Chandra et al.,  2008 ; Roberts, Henriksen, & Foehr,  2009 ).

Not surprisingly, adolescents who are prone to early sexual activity choose to consume more sexualized media (Steinberg & Monahan,  2011 ). The Internet is an especially hazardous “sex educator.” In a survey of a large sample of U.S. 10- to 17-year-old Web users, 42 percent said they had viewed online pornographic websites (images of naked people or people having sex) while surfing the Internet in the past 12 months. Of these, 66 percent indicated they had encountered the images accidentally and did not want to view them (Wolak, Mitchell, & Finkelhor,  2007 ). Youths who felt depressed, had been bullied by peers, or were involved in delinquent activities had more encounters with Internet pornography, which may have intensified their adjustment problems.

Consider the contradictory messages young people receive. On one hand, adults express disapproval of sex at a young age and outside of marriage. On the other hand, the social environment extols sexual excitement, experimentation, and promiscuity. American teenagers are left bewildered, poorly informed about sexual facts, and with little sound advice on how to conduct their sex lives responsibly.

Adolescent Sexual Attitudes and Behavior.

Although differences between subcultural groups exist, sexual attitudes of U.S. adolescents and adults have become more liberal over the past 40 years. Compared with a generation ago, more people believe that sexual intercourse before marriage is all right, as long as two people are emotionally committed to each other (ABC News,  2004 ; Hoff, Greene, & Davis,  2003 ). During the past two decades, adolescents have swung back slightly toward more conservative sexual beliefs, largely in response to the risk of sexually transmitted disease, especially AIDS, and to teenage sexual abstinence programs sponsored by schools and religious organizations (Akers et al.,  2011 ; Ali & Scelfo,  2002 ).

Trends in adolescents’ sexual behavior are consistent with their attitudes. Rates of extramarital sex among U.S. young people rose for several decades, declined during the 1990s, and then stabilized (U.S. Department of Health and Human Services,  2012f ). Nevertheless, as  Figure 11.4  illustrates, a substantial percentage of U.S. young people are sexually active by ninth grade (age 14 to 15).

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FIGURE 11.4 U.S. adolescents who report ever having had sexual intercourse.

Many young adolescents are sexually active—more than in other Western nations. Boys tend to have their first intercourse earlier than girls. By the end of high school, rates of boys and girls having had sexual intercourse are similar.

(From U.S. Department of Health and Human Services, 2012f.)

Overall, teenage sexual activity rates are similar in the United States and other Western countries: Nearly half of adolescents have had intercourse. But quality of sexual experiences differs. U.S. youths become sexually active earlier than their Canadian and European counterparts (Boyce et al.,  2006 ; U.S. Department of Health and Human Services,  2012f ). And about 18 percent of U.S. adolescent boys and 13 percent of girls—more than in other Western nations—have had sexual relations with four or more partners in the past year. Most teenagers, however, have had only one or two sexual partners by the end of high school.

Characteristics of Sexually Active Adolescents.

Early and frequent teenage sexual activity is linked to personal, family, peer, and educational characteristics. These include childhood impulsivity, weak sense of personal control over life events, early pubertal timing, parental divorce, single-parent and stepfamily homes, large family size, little or no religious involvement, weak parental monitoring, disrupted parent–child communication, sexually active friends and older siblings, poor school performance, lower educational aspirations, and tendency to engage in norm-violating acts, including alcohol and drug use and delinquency (Coley, Votruba-Drzal, & Schindler,  2009 ; Crockett, Raffaelli, & Shen,  2006 ; Siebenbruner, Zimmer-Gembeck, & Egeland,  2007 ; Zimmer-Gembeck & Helfand,  2008 ).

Because many of these factors are associated with growing up in a low-income family, it is not surprising that early sexual activity is more common among young people from economically disadvantaged homes. Living in a neighborhood high in physical deterioration, crime, and violence also increases the likelihood that teenagers will be sexually active (Ge et al.,  2002 ). In such neighborhoods, social ties are weak, adults exert little oversight and control over adolescents’ activities, and negative peer influences are widespread. In fact, the high rate of sexual activity among African-American teenagers—60 percent report having had sexual intercourse, compared with 47 percent of all U.S. young people—is largely accounted for by widespread poverty in the black population (Darroch, Frost, & Singh,  2001 ; U.S. Department of Health & Human Services,  2012b ).

Contraceptive Use.

Although adolescent contraceptive use has increased in recent years, about 20 percent of sexually active teenagers in the United States are at risk for unintended pregnancy because they do not use contraception consistently (see  Figure 11.5 ) (Fortenberry,  2010 ). Why do so many fail to take precautions? Typically, teenagers respond, “I was waiting until I had a steady boyfriend,” or “I wasn’t planning to have sex.” As we will see when we take up adolescent cognitive development, although adolescents can consider multiple possibilities when faced with a problem, they often fail to apply this advanced reasoning to everyday situations.

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FIGURE 11.5 Contraceptive use by sexually active 15-year-olds in 10 industrialized nations.

Sexually active U.S. teenagers are less likely to use contraception (condom, contraceptive pill, or both) consistently than teenagers in other industrialized nations.

(Adapted from Godeau et al., 2008; U.S. Department of Health and Human Services, 2012f.)

One reason is that advances in perspective taking lead teenagers, for a time, to be extremely concerned about others’ opinions of them. Recall how Cassie and Louis each worried about what the other would think if they decided not to have sex. Also, in the midst of everyday social pressures, adolescents often overlook the potential consequences of risky behaviors. And many teenagers—especially those from troubled, low-income families—do not have realistic expectations about the impact of early parenthood on their current and future lives (Stevens-Simon, Sheeder, & Harter,  2005 ).

As these findings suggest, the social environment also contributes to teenagers’ reluctance to use contraception. Those without the rewards of meaningful education and work are especially likely to engage in irresponsible sex, sometimes within relationships characterized by exploitation. About 12 percent of U.S. girls and 5 percent of boys say they were pressured to have intercourse when they were unwilling (U.S. Department of Health and Human Services,  2012f ).

In contrast, teenagers who report good relationships with parents and who talk openly with them about sex and contraception are more likely to use birth control (Henrich et al.,  2006 ; Kirby,  2002a ). But few adolescents believe their parents would be understanding and supportive. School sex education classes, as well, often leave teenagers with incomplete or incorrect knowledge. Some do not know where to get birth control counseling and devices. And those engaged in high-risk sexual behaviors are especially likely to worry that a doctor or family planning clinic might not keep their visits confidential (Lehrer et al.,  2007 ). Most of these young people forgo essential health care but continue to have sex without contraception.

Sexual Orientation.

So far, we have focused only on heterosexual behavior. About 4 percent of U.S. 15- to 44-year-olds identify as lesbian, gay, or bisexual (Mosher, Chandra, & Jones,  2005 ). An unknown number experience same-sex attraction but have not come out to friends or family (see the  Social Issues: Health  box on  page 376 ). Adolescence is an equally crucial time for the sexual development of these young people, and societal attitudes, again, loom large in how well they fare.

Heredity makes an important contribution to homosexuality: Identical twins of both sexes are much more likely than fraternal twins to share a homosexual orientation; so are biological (as opposed to adoptive) relatives (Kendler et al.,  2000 ; Kirk et al.,  2000 ). Furthermore, male homosexuality tends to be more common on the maternal than on the paternal side of families, suggesting that it may be X-linked (see  Chapter 2 ). Indeed, one gene-mapping study found that among 40 pairs of homosexual brothers, 33 (82 percent) had an identical segment of DNA on the X chromosome (Hamer et al.,  1993 ). One or several genes in that region might predispose males to become homosexual.

How might heredity lead to homosexuality? According to some researchers, certain genes affect the level or impact of prenatal sex hormones, which modify brain structures in ways that induce homosexual feelings and behavior (Bailey et al.,  1995 ; LeVay,  1993 ). Keep in mind, however, that environmental factors can also alter prenatal hormones. Girls exposed prenatally to very high levels of androgens or estrogens—either because of a genetic defect or from drugs given to the mother to prevent miscarriage—are more likely to become lesbian or bisexual (Meyer-Bahlburg et al.,  1995 ). Furthermore, gay men tend to be later in birth order and to have a higher-than-average number of older brothers (Blanchard & Bogaert,  2004 ). One possibility is that mothers with several male children sometimes produce antibodies to androgens, reducing the prenatal impact of male sex hormones on the brains of later-born boys.

Social Issues: Health Lesbian, Gay, and Bisexual Youths: Coming Out to Oneself and Others

Cultures vary as much in their acceptance of homosexuality as in their approval of extramarital sex. In the United States, homosexuals are stigmatized, as shown by the degrading language often used to describe them. This makes forming a sexual identity a much greater challenge for lesbian, gay, and bisexual youths than for their heterosexual counterparts.

Wide variations in sexual identity formation exist, depending on personal, family, and community factors. Yet interviews with gay and lesbian adolescents and adults reveal that many (though not all) move through a three-phase sequence in coming out to themselves and others.

Feeling Different

Many gay men and lesbians recall feeling different from other children when they were young. Typically, this first sense of their biologically determined sexual orientation appears between ages 6 and 12, in play interests more like those of the other gender (Rahman & Wilson,  2003 ). Boys may find that they are less interested in sports, more drawn to quieter activities, and more emotionally sensitive than other boys; girls that they are more athletic and active than other girls.

By age 10, many of these children start to engage in sexual questioning—wondering why the typical heterosexual orientation does not apply to them. Often, they experience their sense of being different as deeply distressing. Compared with children who are confident of their homosexuality, sexual-questioning children report greater anxiety about peer relationships and greater dissatisfaction with their biological gender over time (Carver, Egan, & Perry,  2004 ).

Confusion

With the arrival of puberty, feeling different clearly encompasses feeling sexually different. In research on ethnically diverse lesbian, gay, and bisexual youths, awareness of a same-sex physical attraction occurred, on average, between ages 11 and 12 for boys and 14 and 15 for girls, perhaps because adolescent social pressures toward heterosexuality are particularly intense for girls (D’Augelli,  2006 ; Diamond,  1998 ).

Realizing that homosexuality has personal relevance generally sparks additional confusion. A few adolescents resolve their discomfort by crystallizing a gay, lesbian, or bisexual identity quickly, with a flash of insight into their sense of being different. But most experience an inner struggle and a deep sense of isolation—outcomes intensified by lack of role models and social support (D’Augelli,  2002 ; Safren & Pantalone,  2006 ).

Some throw themselves into activities they associate with heterosexuality. Boys may go out for athletic teams; girls may drop softball and basketball in favor of dance. And many homosexual youths (more females than males) try heterosexual dating, sometimes to hide their sexual orientation and at other times to develop intimacy skills that they later apply to same-sex relationships (D’Augelli,  2006 ; Dubé, Savin-Williams, & Diamond,  2001 ). Those who are extremely troubled and guilt-ridden may escape into alcohol, drugs, and suicidal thinking. Suicide attempts are unusually high among lesbian, gay, and bisexual young people (Morrow,  2006 ; Teasdale & Bradley-Engen,  2010 ).

Self-Acceptance

By the end of adolescence, the majority of gay, lesbian, and bisexual teenagers accept their sexual identity. But they face another crossroad: whether to tell others. The powerful stigma against their sexual orientation leads some to decide that disclosure is impossible: While self-defining as gay, they otherwise “pass” as heterosexual (Savin-Williams,  2001 ). When homosexual youths do come out, they often face intense hostility, including verbal abuse and physical attacks, because of their sexual orientation. These experiences trigger intense emotional distress, depression, suicidal thoughts, school truancy, and drug use in victims (Almeida et al.,  2009 ; Birkett, Espelage, & Koenig,  2009 ).

Nevertheless, many young people eventually acknowledge their sexual orientation publicly, usually by telling trusted friends first. Once teenagers establish a same-sex sexual or romantic relationship, many come out to parents. Although few parents respond with severe rejection, lesbian, gay, and bisexual young people report lower levels of family support than their heterosexual agemates (Needham & Austin,  2010 ; Savin-Williams & Ream,  2003 ). Yet parental understanding is the strongest predictor of favorable adjustment—including reduced internalized homophobia, or societal prejudice turned against the self (D’Augelli, Grossman, & Starks,  2008 ).

When people react positively, coming out strengthens the young person’s view of homosexuality as a valid, meaningful, and fulfilling identity. Contact with other gays and lesbians is important for reaching this phase, and changes in society permit many adolescents in urban areas to attain it earlier than their counterparts did a decade or two ago. Gay and lesbian communities exist in large cities, along with specialized interest groups, social clubs, religious groups, newspapers, and periodicals. But teenagers in small towns and rural areas may have difficulty meeting other homosexuals and finding a supportive environment. These adolescents have a special need for caring adults and peers who can help them find self- and social acceptance.

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Lesbian, gay, bisexual, and transgender high school students and their allies participate in an annual Youth Pride Festival and March. When peers react with acceptance, coming out strengthens the young person’s view of homosexuality as a valid and fulfilling identity.

Lesbian, gay, and bisexual teenagers who succeed in coming out to themselves and others integrate their sexual orientation into a broader sense of identity, a process we will address in  Chapter 12 . As a result, energy is freed for other aspects of psychological growth. In sum, coming out can foster many facets of adolescent development, including self-esteem, psychological well-being, and relationships with family and friends.

Stereotypes and misconceptions about homosexuality persist. For example, most homosexual adolescents are not “gender-deviant” in dress or behavior. And attraction to members of the same sex is not limited to lesbian, gay, and bisexual teenagers. About 50 to 60 percent of adolescents who report having engaged in homosexual acts identify as heterosexual (Savin-Williams & Diamond,  2004 ). And in a study of lesbian, bisexual, and “unlabeled” young women over a 10-year period, most reported stable proportions of same-sex versus other-sex attractions over time, providing evidence that bisexuality is not, as often assumed, a transient state (Diamond,  2008 ).

The evidence to date suggests that genetic and prenatal biological influences are largely responsible for homosexuality. In our evolutionary past, homosexuality may have served the adaptive function of reducing aggressive competition for other-sex mates (Rahman & Wilson,  2003 ).

Sexually Transmitted Diseases

Sexually active adolescents, both homosexual and heterosexual, are at risk for sexually transmitted diseases (STDs). Adolescents have the highest rates of STDs of all age groups. Despite a recent decline in STDs in the United States, one out of five to six sexually active teenagers contracts one of these illnesses each year—a rate three or more times as high as that of Canada and Western Europe (Centers for Disease Control and Prevention,  2011d ). Teenagers at greatest risk are the same ones most likely to engage in irresponsible sexual behavior: poverty-stricken young people who feel a sense of hopelessness (Niccolai et al.,  2004 ). Left untreated, STDs can lead to sterility and life-threatening complications.

By far the most serious STD is AIDS. In contrast to other Western nations, where the incidence of AIDS among people under age 30 is low, about 15 percent of U.S. AIDS cases occur in young people between ages 20 and 29. Because AIDS symptoms typically do not emerge until 8 to 10 years after infection with the HIV virus, nearly all these cases originated in adolescence. Drug-abusing teenagers who share needles and male adolescents who have sex with HIV-positive same-sex partners account for most cases, but heterosexual spread of the disease remains high, especially among teenagers with more than one partner in the previous 18 months. It is at least twice as easy for a male to infect a female with any STD, including HIV, as for a female to infect a male. Currently, females account for about 25 percent of new U.S. cases among adolescents and young adults (Centers for Disease Control and Prevention,  2011b ).

As a result of school courses and media campaigns, most adolescents are aware of basic facts about AIDS. But they have limited understanding of other STDs, tend to underestimate their own susceptibility, and are poorly informed about how to protect themselves (Copen, Chandra, & Martinez,  2012 ; Ethier et al.,  2003 ; Centers for Disease Control and Prevention,  2007 ).

Furthermore, high school students report engaging in oral sex as early and about as often as intercourse. But few report consistently using STD protection during oral sex, which is a significant mode of transmission of several STDs (Copen, Chandra, & Martinez,  2012 ). Concerted efforts are needed to educate young people about the full range of STDs and risky sexual behaviors.

Adolescent Pregnancy and Parenthood

Cassie didn’t get pregnant after having sex with Louis, but some of her classmates were less fortunate. About 727,000 U.S. teenage girls (12,000 of them younger than age 15)—an estimated 20 percent of those who had sexual intercourse—became pregnant in the most recently reported year. Despite a decline of almost one-half since 1990, the U.S. adolescent pregnancy rate remains higher than that of most other industrialized countries (Ventura, Curtin, & Abma,  2012 ). Three factors heighten the incidence of adolescent pregnancy: (1) Effective sex education reaches too few teenagers; (2) convenient, low-cost contraceptive services for adolescents are scarce; and (3) many families live in poverty, which encourages young people to take risks without considering the future implications of their behavior.

Because about one-fourth of U.S. adolescent pregnancies end in abortion, the number of American teenage births is considerably lower than it was 50 years ago (Ventura, Curtin, & Abma,  2012 ). Still, it is up to nine times higher than in most other developed nations (see  Figure 11.6 ). But teenage parenthood is a much greater problem today because adolescents are far less likely to marry before childbirth. In 1960, only 15 percent of teenage births were to unmarried females, compared with 87 percent today (Child Trends,  2011 ). Increased social acceptance of single motherhood, along with the belief of many teenage girls that a baby might fill a void in their lives, means that very few girls give up their infants for adoption.

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FIGURE 11.6 Birth rates among 15- to 19-year-olds in 15 industrialized nations.

The U.S. adolescent birth rate greatly exceeds that of most other industrialized nations.

(From Centers for Disease Control and Prevention, 2011c.)

Correlates and Consequences of Adolescent Parenthood.

Becoming a parent is especially challenging for adolescents, who have not yet established a clear sense of direction for their own lives. Life conditions and personal attributes jointly contribute to adolescent childbearing and also interfere with teenagers’ capacity to parent effectively.

Teenage parents are far more likely to be poor than age-mates who postpone parenthood. Their backgrounds often include low parental warmth and involvement, domestic violence and child abuse, repeated parental divorce and remarriage, adult models of unmarried parenthood, and residence in neighborhoods where other adolescents also display these risks. Girls at risk for early pregnancy do poorly in school, engage in alcohol and drug use, have a childhood history of aggressive and antisocial behavior, associate with deviant peers, and experience high rates of depression (Elfenbein & Felice,  2003 ; Hillis et al.,  2004 ; Luster & Haddow,  2005 ). A high percentage of out-of-wedlock births are to low-income ethnic minority teenagers. Many turn to early parenthood as a way to move into adulthood when educational and career avenues are unavailable.

The lives of expectant teenagers, already troubled in many ways, tend to worsen in several respects after the baby is born:

· ● Educational attainment. Parenthood before age 18 reduces the likelihood of finishing high school. Only about 70 percent of U.S. adolescent mothers graduate, compared with 95 percent of girls who wait to become parents (National Women’s Law Center,  2007 ).

· ● Marital patterns. Teenage motherhood reduces the chances of marriage and, for those who do marry, increases the likelihood of divorce compared with peers who delay child-bearing (Moore & Brooks-Gunn,  2002 ). Consequently, teenage mothers spend more of their parenting years as single parents. About 35 percent become pregnant again within two years. Of these, about half go on to deliver a second child (Child Trends,  2011 ).

· ● Economic circumstances. Because of low educational attainment, marital instability, and poverty, many teenage mothers are on welfare or work in unsatisfying, low-paid jobs. Similarly, many adolescent fathers are unemployed or earn too little to provide their children with basic necessities (Bunting & McAuley,  2004 ). An estimated 50 percent have committed illegal offenses resulting in imprisonment (Elfenbein & Felice,  2003 ). And for both mothers and fathers, reduced educational and occupational attainment often persists well into adulthood (Taylor,  2009 ).

Because many pregnant teenage girls have inadequate diets, smoke, use alcohol and other drugs, and do not receive early prenatal care, their babies often experience pregnancy and birth complications—especially preterm and low birth weight (Khashan, Baker, & Kenny,  2010 ). And compared with adult mothers, adolescent mothers know less about child development, have unrealistically high expectations of infants, perceive their babies as more difficult, interact less effectively with them, and more often engage in child abuse (Moore & Florsheim,  2001 ; Pomerleau, Scuccimarri, & Malcuit,  2003 ; Sieger & Renk,  2007 ). Their children tend to score low on intelligence tests, achieve poorly in school, and engage in disruptive social behavior.

Furthermore, adolescent parenthood frequently is repeated in the next generation (Brooks-Gunn, Schley, & Hardy,  2002 ). In longitudinal studies that followed mothers—some who gave birth as teenagers, others who postponed parenting—and their children for several decades, mothers’ age at first childbirth strongly predicted the age at which their daughters and sons became parents. The researchers found that adolescent parenthood was linked to a set of related unfavorable family conditions and personal characteristics that negatively influenced development over an extended time and, therefore, often transferred to the next generation. Among influential factors was father absence (Barber, 2001a; Campa & Eckenrode,  2006 ; Meade, Kershaw, & Ickovics,  2008 ). Consistent with findings reported earlier for sexual activity and pregnancy, far greater intergenerational continuity, especially for daughters, occurred when teenage mothers remained unmarried.

Even when children born to teenage mothers do not become early childbearers, their development is often compromised, in terms of likelihood of high school graduation, financial independence in adulthood, and long-term physical and mental health (Moore, Morrison, & Greene,  1997 ; Pogarsky, Thornberry, & Lizotte,  2006 ). Still, outcomes vary widely. If a teenage parent finishes high school, secures gainful employment, avoids additional births, and finds a stable partner, long-term disruptions in her own and her child’s development will be less severe.

Prevention Strategies.

Preventing teenage pregnancy means addressing the many factors underlying early sexual activity and lack of contraceptive use. Too often, sex education courses are given late (after sexual activity has begun), last only a few sessions, and are limited to a catalog of facts about anatomy and reproduction. Sex education that goes beyond this minimum does not encourage early sex, as some opponents claim (Kirby,  2002c ). It does improve awareness of sexual facts—knowledge that is necessary for responsible sexual behavior.

Knowledge, however, is not enough: Sex education must also help teenagers build a bridge between what they know and what they do. Effective sex education programs include several key elements:

· ● They teach techniques for handling sexual situations—including refusal skills for avoiding risky sexual behaviors and communication skills for improving contraceptive use—through role-playing and other activities.

· ● They deliver clear, accurate messages that are appropriate in view of participating adolescents’ culture and sexual experiences.

· ● They last long enough to have an impact.

· ● They provide specific information about contraceptives and ready access to them.

Many studies show that sex education with these components can delay the initiation of sexual activity, reduce the frequency of sex and the number of sexual partners, increase contraceptive use, change attitudes (for example, strengthen future orientation), and reduce pregnancy rates (Kirby,  2002b ; Kirby & Laris,  2009 ; Thomas & Dimitrov,  2007 ).

LOOK AND LISTEN

Contact a nearby public school district for information about its sex education curriculum. Considering research findings, do you think it is likely to be effective in delaying initiation of sexual activity and reducing adolescent pregnancy rates?

Proposals to increase access to contraceptives are the most controversial aspect of U.S. adolescent pregnancy prevention efforts. Many adults argue that placing birth control pills or condoms in the hands of teenagers is equivalent to approving of early sex. Yet sex education programs encouraging abstinence without encouraging contraceptive use have little or no impact on delaying teenage sexual activity or preventing pregnancy (Rosenbaum,  2009 ; Underhill, Montgomery, & Operario,  2007 ). In Canada and Western Europe, where community- and school-based clinics offer adolescents contraceptives and where universal health insurance helps pay for them, teenage sexual activity is no higher than in the United States—but pregnancy, childbirth, and abortion rates are much lower (Schalet,  2007 ).

Efforts to prevent adolescent pregnancy and parenthood must go beyond improving sex education and access to contraception to build academic and social competence (Allen, Seitz, & Apfel,  2007 ). In one study, researchers randomly assigned at-risk high school students either to a year-long community service class, called Teen Outreach, or to regular classroom experiences in health or social studies. In Teen Outreach, adolescents spent at least 20 hours per week in volunteer work tailored to their interests. They returned to school for discussions that focused on enhancing their community service skills and their ability to cope with everyday challenges. At the end of the school year, rates of pregnancy, school failure, and school suspension were substantially lower among participants in Teen Outreach, which fostered social skills, connection to the community, and self-respect (Allen et al.,  1997 ).

Finally, teenagers who look forward to a promising future are far less likely to engage in early and irresponsible sex. By expanding educational, vocational, and employment opportunities, society can give young people good reasons to postpone childbearing.

Intervening with Adolescent Parents.

The most difficult and costly way to deal with adolescent parenthood is to wait until it happens. Young parents need health care, encouragement to stay in school, job training, instruction in parenting and life-management skills, and high-quality, affordable child care. Schools that provide these services reduce the incidence of low-birth-weight babies, increase educational success, and prevent additional childbearing (Key et al.,  2008 ; Seitz & Apfel,  2005 ).

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Early parenthood imposes lasting hardships on adolescent parents and their newborn babies. But the involvement of a caring father and a stable partnership between the parents can improve outcomes for young families.

Adolescent mothers also benefit from relationships with family members and other adults who are sensitive to their developmental needs. In one study, African-American teenage mothers who had a long-term “mentor” relationship—an aunt, neighbor, or teacher who provided emotional support and guidance—were far more likely than those without a mentor to stay in school and graduate (Klaw, Rhodes, & Fitzgerald,  2003 ). Home visiting programs are also effective. Return to  page 94  in  Chapter 3  to review the Nurse–Family Partnership, which helps launch teenage mothers and their babies on a favorable life course.

Programs focusing on fathers attempt to increase their financial and emotional commitment to the baby. Although nearly half of young fathers visit their children during the first few years, contact usually diminishes. By the time the child starts school, fewer than one-fourth have regular paternal contact. As with teenage mothers, support from family members helps fathers stay involved (Bunting & McAuley,  2004 ). Teenage mothers who receive financial and child-care assistance and emotional support from their child’s father are less distressed and more likely to sustain a relationship with him (Cutrona et al.,  1998 ; Gee & Rhodes,  2003 ). And infants with lasting ties to their teenage fathers show better long-term adjustment (Florsheim & Smith,  2005 ; Furstenberg & Harris,  1993 ).

Substance Use and Abuse

At age 14, Louis waited until he was alone at home, took some cigarettes from his uncle’s pack, and smoked. At an unchaperoned party, he and Cassie drank several cans of beer and lit up marijuana joints. Louis got little physical charge out of these experiences. A good student, who was well-liked by peers and got along well with his parents, he did not need drugs as an escape valve. But he knew of other teenagers who started with alcohol and cigarettes, moved on to harder substances, and eventually were hooked.

Teenage alcohol and drug use is pervasive in industrialized nations. According to the most recent nationally representative survey of U.S. high school students, by tenth grade, 33 percent of U.S. young people have tried cigarette smoking, 58 percent drinking, and 37 percent at least one illegal drug (usually marijuana). At the end of high school, 11 percent smoke cigarettes regularly, and 27 percent have engaged in heavy drinking during the past month. About 25 percent have tried at least one highly addictive and toxic substance, such as amphetamines, cocaine, phencyclidine (PCP), Ecstasy (MDMA), inhalants, heroin, sedatives (including barbiturates), or OxyContin (a narcotic painkiller) (Johnston et al.,  2011 ).

These figures represent a substantial decline since the mid-1990s, probably resulting from greater parent, school, and media focus on the hazards of drug use. But use of marijuana, inhalants, sedatives, and OxyContin has risen slightly in recent years (Johnston et al.,  2011 ). Other drugs, such as LSD, PCP, and Ecstasy, have made a comeback as adolescents’ knowledge of their risks faded.

In part, drug taking reflects the sensation seeking of the teenage years. But adolescents also live in drug-dependent cultural contexts. They see adults relying on caffeine to stay alert, alcohol and cigarettes to cope with daily hassles, and other remedies to relieve stress, depression, and physical discomfort. And compared to a decade or two ago, today doctors more often prescribe—and parents frequently seek—medication to treat children’s problems (Olfman & Robbins,  2012 ). In adolescence, these young people may readily “self-medicate” when stressed.

Most teenagers who dabble in alcohol, tobacco, and marijuana are not headed for a life of addiction. These minimal experimenters are usually psychologically healthy, sociable, curious young people (Shedler & Block,  1990 ). As  Figure 11.7  shows, tobacco and alcohol use is somewhat greater among European than U.S. adolescents, perhaps because European adults more often smoke and drink. But illegal drug use is far more prevalent among U.S. teenagers. A greater percentage of American young people live in poverty, which is linked to family and peer contexts that promote illegal drug use. At the same time, use of diverse drugs is lower among African Americans than among Hispanic and Caucasian Americans; Native-American youths rank highest in drug taking (Johnston et al.,  2011 ). Researchers have yet to explain these variations.

Adolescent experimentation with any drug should not be taken lightly. Because most drugs impair perception and thought processes, a single heavy dose can lead to permanent injury or death. And a worrisome minority of teenagers move from substance use to abuse—taking drugs regularly, requiring increasing amounts to achieve the same effect, moving on to harder substances, and using enough to interfere with their ability to meet daily responsibilities.

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FIGURE 11.7 Tenth-grade students in the United States and Europe who have used various substances.

Rates for tobacco and alcohol are based on any use in the past 30 days. Rates for marijuana and other illegal drugs are based on any lifetime use. Tobacco use and alcohol use are greater for European adolescents, whereas illegal drug use is greater for U.S. adolescents.

(Adapted from ESPAD, 2012; Johnson et al., 2011.)

Correlates and Consequences of Adolescent Substance Abuse.

Unlike experimenters, drug abusers are seriously troubled young people. Their impulsive, disruptive, hostile style is often evident in early childhood, and they are inclined to express their unhappiness through antisocial acts. Compared with other young people, their drug taking starts earlier and may have genetic roots (Dick, Prescott, & McGue,  2008 ; Tarter, Vanyukov, & Kirisci,  2008 ). But environmental factors also contribute. These include low SES, family mental health problems, parental and older sibling drug abuse, lack of parental warmth and involvement, physical and sexual abuse, and poor school performance. Especially among teenagers with family difficulties, encouragement from friends who use and provide drugs increases substance abuse (Ohannessian & Hesselbrock,  2008 ; U.S. Department of Health and Human Services,  2010c ).

Introducing drugs while the adolescent brain is still a work-in-progress can have profound, lasting consequences, impairing neurons and their connective networks. At the same time, teenagers who use substances to deal with daily stresses fail to learn responsible decision-making skills and alternative coping techniques. They show serious adjustment problems, including chronic anxiety, depression, and antisocial behavior, that are both cause and consequence of heavy drug taking (Kassel et al.,  2005 ; U.S. Department of Health and Human Services,  2010c ). And they often enter into marriage, childbearing, and the work world prematurely and fail at them—painful outcomes that further promote addictive behavior.

Prevention and Treatment.

School and community programs that reduce drug experimentation typically combine several components:

· ● They promote effective parenting, including monitoring of teenagers’ activities.

· ● They teach skills for resisting peer pressure.

· ● They reduce the social acceptability of drug taking by emphasizing health and safety risks (Cuijpers,  2002 ; Stephens et al.,  2009 ).

But given that adolescent drug taking is widespread, interventions that prevent teenagers from harming themselves and others when they do experiment are essential. Many communities offer weekend on-call transportation services that any young person can contact for a safe ride home, with no questions asked.

Because drug abuse has different roots than occasional use, different prevention strategies are required. One approach is to work with parents early, reducing family adversity and improving parenting skills, before children are old enough for drug involvement (Velleman, Templeton, & Copello,  2005 ). Programs that teach at-risk teenagers effective strategies for handling life stressors and that build competence through community service reduce alcohol and drug abuse, just as they reduce teenage pregnancy.

When an adolescent becomes a drug abuser, family and individual therapy are generally needed to treat maladaptive parent–child relationships, impulsivity, low self-esteem, anxiety, and depression. Academic and vocational training to improve life success also helps. But even comprehensive programs have alarmingly high relapse rates—from 35 to 85 percent (Brown & Ramo,  2005 ; Sussman, Skara, & Ames,  2008 ). One recommendation is to start treatment gradually, through support-group sessions that focus on reducing drug taking (Myers et al.,  2001 ). Modest improvements may increase young people’s motivation to make longer-lasting changes through intensive treatment.

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Teenagers enjoy a community party sponsored by Drug Free Youth in Town (DFYIT), a substance abuse prevention program. DFYIT trains high school students as peer educators, who teach middle school students life skills and strategies for resisting peer pressure.

ASK YOURSELF

REVIEW Compare risk factors for anorexia nervosa and bulimia nervosa. How do treatments and outcomes differ for the two disorders?

CONNECT What unfavorable life experiences do teenagers who engage in early and frequent sexual activity have in common with those who abuse drugs?

APPLY After 17-year-old Veronica gave birth to Ben, her parents told her they didn’t have room for the baby. Veronica dropped out of school and moved in with her boyfriend, who soon left. Why are Veronica and Ben likely to experience long-term hardships?

REFLECT Describe your experiences with peer pressure to experiment with alcohol and drugs. What factors influenced your response?

COGNITIVE DEVELOPMENT

One mid-December evening, a knock at the front door announced the arrival of Franca and Antonio’s oldest son, Jules, home for vacation after the fall semester of his sophomore year at college. The family gathered around the kitchen table. “How did it all go, Jules?” asked Antonio as he served slices of apple pie.

“Well, physics and philosophy were awesome,” Jules responded with enthusiasm. “The last few weeks, our physics prof introduced us to Einstein’s theory of relativity. Boggles my mind, it’s so incredibly counterintuitive.”

“Counter-what?” asked 11-year-old Sabrina.

“Counterintuitive. Unlike what you’d normally expect,” explained Jules. “Imagine you’re on a train, going unbelievably fast, like 160,000 miles a second. The faster you go, approaching the speed of light, the slower time passes and the denser and heavier things get relative to on the ground. The theory revolutionized the way we think about time, space, matter—the entire universe.”

Sabrina wrinkled her forehead, baffled by Jules’s otherworldly reasoning. “Time slows down when I’m bored, like right now, not on a train when I’m going somewhere exciting. No speeding train ever made me heavier, but this apple pie will if I eat any more of it,” Sabrina announced, leaving the table.

Sixteen-year-old Louis reacted differently. “Totally cool, Jules. So what’d you do in philosophy?”

“It was a course in philosophy of technology. We studied the ethics of futuristic methods in human reproduction. For example, we argued the pros and cons of a world in which all embryos develop in artificial wombs.”

“What do you mean?” asked Louis. “You order your kid at the lab?”

“That’s right. I wrote my term paper on it. I had to evaluate it in terms of principles of justice and freedom. I can see some advantages but also lots of dangers….”

As this conversation illustrates, adolescence brings with it vastly expanded powers of reasoning. At age 11, Sabrina finds it difficult to move beyond her firsthand experiences to a world of possibilities. Over the next few years, her thinking will acquire the complex qualities that characterize the cognition of her older brothers. Jules and Louis consider multiple variables simultaneously and think about situations that are not easily detected in the real world or that do not exist at all. As a result, they can grasp advanced scientific and mathematical principles and grapple with social and political issues. Compared with school-age children’s thinking, adolescent thought is more enlightened, imaginative, and rational.

Systematic research on adolescent cognitive development began with testing of Piaget’s ideas (Kuhn,  2009 ). Recently, information-processing research has greatly enhanced our understanding.

image27 Piaget’s Theory: The Formal Operational Stage

According to Piaget, around age 11 young people enter the  formal operational stage , in which they develop the capacity for abstract, systematic, scientific thinking. Whereas concrete operational children can “operate on reality,” formal operational adolescents can “operate on operations.” They no longer require concrete things or events as objects of thought. Instead, they can come up with new, more general logical rules through internal reflection (Inhelder & Piaget,  1955 / 1958 ). Let’s look at two major features of the formal operational stage.

Hypothetico-Deductive Reasoning

Piaget believed that at adolescence, young people first become capable of  hypothetico-deductive reasoning . When faced with a problem, they start with a hypothesis, or prediction about variables that might affect an outcome, from which they deduce logical, testable inferences. Then they systematically isolate and combine variables to see which of these inferences are confirmed in the real world. Notice how this form of problem solving begins with possibility and proceeds to reality. In contrast, concrete operational children start with reality—with the most obvious predictions about a situation. If these are not confirmed, they usually cannot think of alternatives and fail to solve the problem.

Adolescents’ performance on Piaget’s famous pendulum problem illustrates this approach. Suppose we present several school-age children and adolescents with strings of different lengths, objects of different weights to attach to the strings, and a bar from which to hang the strings (see  Figure 11.8 ). Then we ask each of them to figure out what influences the speed with which a pendulum swings through its arc.

Formal operational adolescents hypothesize that four variables might be influential: (1) the length of the string, (2) the weight of the object hung on it, (3) how high the object is raised before it is released, and (4) how forcefully the object is pushed. By varying one factor at a time while holding the other three constant, they test each variable separately and, if necessary, also in combination. Eventually they discover that only string length makes a difference.

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FIGURE 11.8 Piaget’s pendulum problem.

Adolescents who engage in hypothetico-deductive reasoning think of variables that might possibly affect the speed with which a pendulum swings through its arc. Then they isolate and test each variable, as well as testing the variables in combination. Eventually they deduce that the weight of the object, the height from which it is released, and how forcefully it is pushed have no effect on the speed with which the pendulum swings through its arc. Only string length makes a difference.

In contrast, concrete operational children cannot separate the effects of each variable. They may test for the effect of string length without holding weight constant—comparing, for example, a short, light pendulum with a long, heavy one. Also, they typically fail to notice variables that are not immediately suggested by the concrete materials of the task—for example, how high the object is raised or how forcefully it is released.

Propositional Thought

A second important characteristic of Piaget’s formal operational stage is  propositional thought —adolescents’ ability to evaluate the logic of propositions (verbal statements) without referring to real-world circumstances. In contrast, children can evaluate the logic of statements only by considering them against concrete evidence in the real world.

In a study of propositional reasoning, a researcher showed children and adolescents a pile of poker chips and asked whether statements about the chips were true, false, or uncertain (Osherson & Markman,  1975 ). In one condition, the researcher hid a chip in her hand and presented the following propositions:

·  “Either the chip in my hand is green or it is not green.”

·  “The chip in my hand is green and it is not green.”

In another condition, the experimenter made the same statements while holding either a red or a green chip in full view.

School-age children focused on the concrete properties of the poker chips. When the chip was hidden, they replied that they were uncertain about both statements. When it was visible, they judged both statements to be true if the chip was green and false if it was red. In contrast, adolescents analyzed the logic of the statements. They understood that the “either-or” statement is always t

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