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CHAPTER 11
PHYSICAL AND COGNITIVE DEVELOPMENT IN ADOLESCENCE
LEARNING OBJECTIVES
After reading this chapter, you should be able to answer the following:
11.1 How have conceptions of adolescence changed over the past century? (p. 287–288)
11.2 Describe body growth, motor performance, and sexual maturation during puberty. (pp. 288–290)
11.3 What factors influence the timing of puberty? (pp. 290–291)
11.4 What changes in the brain take place during adolescence? (pp. 291–292)
11.5 Explain adolescents’ reactions to the physical changes of puberty. (pp. 292–294)
11.6 Discuss the impact of pubertal timing on adolescent adjustment, noting sex differences. (pp. 294–295)
11.7 Describe nutritional needs during adolescence, and cite factors related to eating disorders. (pp. 295–297)
11.8 Discuss social and cultural influences on adolescent sexual attitudes and behavior. (pp. 297–298)
11.9 Cite factors involved in the development of homosexuality. (pp. 298–300)
11.10 Discuss factors related to sexually transmitted disease and teenage pregnancy and parenthood, noting prevention and intervention strategies. (pp. 300–302)
11.11 What personal and social factors are related to adolescent substance use and abuse? (pp. 302–303)
11.12 What are the major characteristics of formal operational thought? (pp. 304–305)
11.13 Discuss follow-up research on formal operational thought and its implications for the accuracy of Piaget’s formal operational stage. (pp. 305–306)
11.14 How do information-processing researchers account for cognitive changes in adolescence? (pp. 306–307)
11.15 Describe typical reactions of adolescents that result from their advancing cognition. (pp. 307–309)
11.17 Discuss the impact of school transitions on adolescent adjustment. (pp. 309–310)
11.18 Discuss family, peer, and school influences on academic achievement during adolescence. (pp. 310–313)
11.19 What factors increase the risk of high school dropout? (pp. 313–314)
LECTURE OUTLINE
Physical Development
I. CONCEPTIONS OF ADOLESCENCE (p. 287–288)
A. The beginning of adolescence, the transition between childhood and adulthood, is marked by puberty, a flood of biological events leading to an adult-sized body and sexual maturity.
1. The widespread view of adolescence as a turbulent period goes back to the “storm-and-stress” perspective of G. Stanley Hall and other major theorists of the early twentieth century.
3. Anthropologist Margaret Mead promoted the view that the social environment is entirely responsible for the range of teenage experiences, both negative and positive.
4. Today we know that biological, psychological, and social forces combine to influence adolescent development.
5. The length of adolescence and its demands and pressures differ widely among cultures.
a. Most tribal and village societies have only a brief intervening phase between childhood and adulthood.
b. In industrialized societies, where young people face prolonged dependence on parents and postponement of sexual gratification while they prepare for a productive work life, adolescence is greatly extended.
II. PUBERTY: THE PHYSICAL TRANSITION TO ADULTHOOD (pp. 288–292)
A. Genetically influenced hormonal processes regulate pubertal growth.
B. Girls reach puberty, on average, two years earlier than boys.
C. Hormonal Changes (p. 288)
1. The hormonal changes underlying puberty are under way by age 8 or 9, when secretions of growth hormone (GH) and thyroxine increase, leading to enormous gains in body size and to attainment of skeletal maturity.
2. Sexual maturation is controlled by the sex hormones.
3. Pubertal changes are of two broad types: overall body growth and maturation of sexual characteristics.
D. Body Growth (pp. 288–289)
1. The first outward sign of puberty is the rapid gain in height and weight called the growth spurt, during which adolescents add 10 to 11 inches in height and 50 to 75 pounds. Growth is complete for most girls by age 16 and for boys by age 171⁄2.
2. Body Proportions and Muscle–Fat Makeup
a. Growth of the hands, legs, and feet accelerates first, followed by the torso.
E. Motor Development and Physical Activity (pp. 289–290)
1. Girls’ gains in gross-motor performance are slow and gradual, leveling off at age 14, whereas boys show a dramatic spurt in strength, speed, and endurance that continues through the teenage years.
F. Sexual Maturation (pp. 290, 291)
1. In adolescence, changes occur in physical features related to sexual functioning.
a. Primary sexual characteristics involve the reproductive organs.
b. Secondary sexual characteristics are additional signs of sexual maturity that are visible on the outside of the body.
3. Sexual Maturation in Girls
a. Female puberty usually begins with the budding of the breasts and the growth spurt.
b. Menarche, or first menstruation, typically occurs around age 121⁄2 for North American girls and 13 for Western Europeans.
4. Sexual Maturation in Boys
a. The first sign of puberty in boys is the enlargement of the testes, accompanied by changes in the scrotum.
G. Individual Differences in Pubertal Growth (pp. 290–291)
1. Heredity contributes substantially to the timing of pubertal changes. Nutrition and exercise also have an effect.
5. The existence of a secular trend, or generational change, in pubertal timing lends added support to the role of physical well-being in pubertal development.
H. Brain Development (pp. 291–292)
1. Brain-imaging research reveals continued pruning of unused synapses in the cerebral cortex during adolescence.
3. However, fMRI evidence reveals that adolescents recruit the prefrontal cortex’s network of connections with other brain areas less effectively than adults do, and teenagers’ performance on executive function tasks requiring inhibition, planning, and future orientation is not yet fully mature.
III. THE PSYCHOLOGICAL IMPACT OF PUBERTAL EVENTS (pp. 292–295)
A. Reactions to Pubertal Changes (pp. 292–293)
1. Girls today typically report a mixture of positive and negative emotions at menarche, but wide individual differences exist, depending on prior knowledge and support from family members.
2. Boys’ responses to spermarche also reflect mixed feelings; those who feel better prepared tend to react more positively.
B. Pubertal Change, Emotion, and Social Behavior (pp. 293–294)
1. Adolescent Moodiness
a. Higher pubertal hormone levels are modestly linked to greater moodiness.
b. Several studies tracking moods of children, adolescents, and adults found that several other factors contribute.
(1) Adolescents’ negative moods were linked to a greater number of negative life events, such as conflicts with parents and disciplinary actions at school.
2. Parent–Child Relationships
a. Puberty is related to a rise in intensity of parent–child conflict, which persists into middle adolescence.
b. Psychological distancing between parents and children seems to have emerged as a substitute for the physical departure from the family that is typical in many nonindustrialized cultures and among nonhuman primates.
c. Parent–adolescent disagreements focus largely on everyday matters such as dating partners and curfews.
C. Pubertal Timing (pp. 294–295)
1. In studies of pubertal timing, early-maturing boys were viewed by both adults and peers as relaxed, independent, self-confident, and physically attractive, whereas early-maturing girls were unpopular, withdrawn, lacking in selfconfidence, anxious, and prone to depression.
3. The Role of Physical Attractiveness
a. Society’s view of an attractive female is thin and long-legged—a girlish shape that favors the late developer.
b. The good-looking male image—tall, broad-shouldered, and muscular—fits the early-maturing boy.
c. Body image—conception of and attitude toward one’s physical appearance—is a strong predictor of young people’s self-esteem.
4. The Importance of Fitting in with Peers
a. Adolescents feel most comfortable with peers who match their own level of biological maturity.
5. Long-Term Consequences
a. Early-maturing girls are prone to lasting difficulties, compared to their on-time counterparts.
b. In contrast, early-maturating boys show good long-term adjustment.
IV. HEALTH ISSUES (pp. 295–303)
A. As adolescents attain greater autonomy, personal decision making becomes important, in health as well as other areas.
B. Nutritional Needs (p. 295)
1. Puberty leads to a dramatic increase in nutritional requirements, at a time when the diets of many young people are the poorest.
C. Eating Disorders (pp. 296–297)
1. 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.
2. Anorexia Nervosa
a. Anorexia nervosa, an eating disorder in which young people starve themselves because of a compulsive fear of getting fat, affects about 1 percent of North American and Western European teenage girls.
b. Cases have increased sharply in the past 50 years, fueled by cultural admiration of female thinness.
c. 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.
3. Bulimia Nervosa
a. In bulimia nervosa, young people—mainly girls, but also some gay and bisexual boys—engage in strict dieting and excessive exercise accompanied by binge eating, often followed by deliberate vomiting and purging with laxatives.
b. Bulimia typically appears in late adolescence and is more common than anorexia, affecting about 2 to 4 percent of teenage girls.
e. In contrast to young people with anorexia, those with bulimia usually feel depressed and guilty about their abnormal eating habits, making bulimia easier to treat than anorexia.
D. Sexuality (pp. 297–300)
1. The Impact of Culture
a. Typically, North American parents give children little or no information about sex, discourage sex play, and rarely talk about sex in children’s presence.
(2) In a large survey, 42 percent of U.S. 10- to 17-year-old Web users said they had viewed online pornography—66 percent accidentally—while surfing the Internet.
2. Characteristics of Sexually Active Adolescents
a. Overall, teenage sexual activity rates are similar in the United States and other Western countries: Nearly half of adolescents have had intercourse.
3. Contraceptive Use
a. Adolescent contraceptive use has increased in recent years, but about 20 percent of sexually active U.S. teenagers do not use contraception consistently.
c. Teenagers who talk openly with their parents about sex and contraception are more likely to use birth control.
4. Sexual Orientation
a. About 4 percent of U.S. 15- to 44-year-olds identify as lesbian, gay, or bisexual.
E. Sexually Transmitted Diseases (p. 300)
1. Sexually active adolescents have the highest rates of sexually transmitted diseases (STDs) of all age groups. One out of five to six sexually active U.S. teenagers contracts an STD each year—a rate three or more times as high as that of Canada and Western Europe.
F. Adolescent Pregnancy and Parenthood (pp. 300–302)
1. In the most recently reported year, about 727,000 U.S. teenage girls become pregnant, 12,000 of them younger than age 15.
2. The U.S. adolescent pregnancy rate remains higher than that of most other industrialized countries.
3. Because about one-fourth of U.S. teenage pregnancies end in abortion, the number of teenage births is considerably lower than it was 50 years ago.
4. However, adolescents who do give birth are far less likely than in the past to marry before childbirth, and very few girls give up their infants for adoption.
5. Correlates and Consequences of Adolescent Parenthood
a. Teenage parents have life conditions and personal attributes that interfere with their ability to parent effectively.
6. Prevention Strategies
a. Preventing teenage pregnancy means addressing the factors underlying early sexual activity and lack of contraceptive use.
d. In Canada and Western Europe, where contraceptives are available to teenagers and subsidized by universal health insurance, teenage sexual activity is no higher than in the United States—but pregnancy, childbirth, and abortion rates are lower.
G. Substance Use and Abuse (pp. 302–303)
1. 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)—figures that represent a substantial decline since the mid-1990s.
5. Correlates and Consequences of Adolescent Substance Abuse
a. Unlike experimenters, drug abusers are seriously troubled adolescents whose impulsive, disruptive, hostile style is often evident in early childhood.
6. Prevention and Treatment
a. School and community programs that reduce drug experimentation typically teach skills for resisting peer
pressure, emphasize the health and safety risks, and get adolescents to commit to not using drugs.
Cognitive Development
V. PIAGET’S THEORY: THE FORMAL OPERATIONAL STAGE (pp. 304–306)
A. According to Piaget, around age 11, young people enter the formal operational stage, in which they develop the capacity for abstract, systematic scientific thinking.
B. Hypothetico-Deductive Reasoning (pp. 304–305)
1. Piaget believed that adolescents become capable of hypothetico-deductive reasoning, a problem-solving strategy in which they begin with a hypothesis, from which they deduce logical, testable inferences.
C. Propositional Thought (p. 305)
1. Propositional thought refers to adolescents’ ability to evaluate the logic of propositions (verbal statements) without referring to real-world circumstances.
2. Formal operations require language-based and other symbolic systems that do not stand for real things as well as
verbal reasoning about abstract concepts.
D. Follow-Up Research on Formal Operational Thought (pp. 305–306)
2. Do All Individuals Reach the Formal Operational Stage?
VI. AN INFORMATION-PROCESSING VIEW OF ADOLESCENT COGNITIVE DEVELOPMENT (pp. 306–307)
A. Information-processing theorists refer to a variety of specific mechanisms underlying cognitive gains in adolescence.
1. Attention becomes more selective.
2. Inhibition improves.
3. Strategies become more effective.
4. Knowledge increases.
5. Metacognition expands.
6. Cognitive self-regulation improves.
7. Speed of thinking and processing capacity increase.
B. One of these mechanisms of change—metacognition—is central to adolescent cognitive development.
C. Scientific Reasoning: Coordinating Theory with Evidence (pp. 306–307): The ability to distinguish theory from evidence and use logical rules to examine their relationship improves steadily from childhood into adolescence and adulthood.
D. How Scientific Reasoning Develops (p. 307)
1. Greater working-memory capacity permits a theory and the effects of several variables to be compared at once.
VII. CONSEQUENCES OF ADOLESCENT COGNITIVE CHANGES (pp. 307–309)
A. Self-Consciousness and Self-Focusing (p. 308)
1. Adolescents’ ability to reflect on their own thoughts, combined with physical and psychological changes, leads them to think more about themselves.
2. From a Piagetian perspective, two distorted images of the relation between self and other commonly appear.
a. The imaginary audience refers to adolescents’ belief that they are the focus of everyone else’s attention and concern.
b. The personal fable is adolescents’ inflated opinion of their own importance—the feeling that they are special and unique.
B. Idealism and Criticism (p. 308)
1. Because adolescents are able to think about possibilities, they can imagine an ideal world and want to explore alternative family, religious, political, and moral systems.
C. Decision Making (pp. 308–309)
1. Teenagers often perform less well than adults in decision making, where they must inhibit emotion and impulses in favor of thinking rationally.
VIII. LEARNING IN SCHOOL (pp. 309–314)
A. School Transitions (pp. 309–310)
1. Impact of School Transitions
a. School transitions can create adjustment problems that lead to a decline in adolescents’ grades with each school change.
2. Helping Adolescents Adjust to School Transitions
a. School transitions often lead to environmental changes that fit poorly with adolescents’ developmental needs, but support from parents, teachers, and peers can ease these strains.
B. Academic Achievement (pp. 310–313)
1. Positive educational environments, both family and school, lead to personal traits that support achievement, such as confidence in one’s abilities and the desire to succeed.
2. Child-Rearing Styles
a. Authoritative child rearing is linked to higher grades among adolescents varying widely in SES.
3. Parent–School Partnerships
a. High-achieving students typically have parents who monitor their child’s progress, communicate with teachers, and make sure their child’s classes are challenging and well-taught.
4. Peer Influences
a. Teenagers whose parents value achievement generally choose friends who share those values.
c. Research confirms that teenagers’ media multitasking—in classrooms and while studying at home—greatly reduces learning.
C. Dropping Out (pp. 313–314)
1. About 8 percent of U.S. 16- to 24-year-olds drop out of high school and remain without a diploma or a GED. The dropout rate is higher among boys than girls and is particularly high among low-SES ethnic minority youths.
3. Factors Related to Dropping Out
a. Although many dropouts achieve poorly and show high rates of norm-violating acts, a substantial number have few behavior problems, experience academic difficulties, and quietly disengage from school.