Steinberg13_ppt_ch01_ADA_Final

1. Adolescence, 13eLaurence Steinberg Chapter 1 – Biological transitions © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

2. Chapter 1 Overview (1) • Puberty: An Overview • The Endocrine System • What Triggers Puberty? • How Hormones Influence Adolescent Development • Somatic Development • The Adolescent Growth Spurt • Sexual Maturation • The Timing and Tempo of Puberty • Variations in the Timing and Tempo of Puberty • Genetic and Environmental Influences on Pubertal Timing © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

3. Chapter 1 Overview (2) • The Psychological and Social Impact of Puberty • The Immediate Impact of Puberty • The Impact of Specific Pubertal Events • The Impact of Early or Late Maturation • Obesity and Eating Disorders • Obesity • Anorexia Nervosa, Bulimia, and Binge Eating Disorder © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

4. Puberty: An Overview Puberty • It is the period during which an individual becomes capable of sexual reproduction. • More broadly, it includes all the physical changes that occur in adolescents. • Hormones regulated by the endocrine system lead to physical changes. • No new hormones are produced and no new bodily systems develop at puberty. © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

5. The Endocrine System (1) It produces, circulates, and regulates hormone levels in the body. • Hormones: Specialized substances secreted by endocrine glands • Glands: Organs that stimulate particular parts of the body to respond in specific ways • Gonadotropin-releasing hormone (GnRH) neurons: Neurons in the brain that play important roles at puberty Hormonal feedback loop (HPG axis) • Set point (e.g., thermostat) © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

6. The Endocrine System (2) The Hormonal Feedback Loop Figure 1.1: Levels of sex hormones are regulated by a feedback system composed of the hypothalamus, pituitary gland, and gonads. Access the text alternative for slide images.

7. The endocrine system (3) • Adrenarche • Just before puberty, early sexual feelings may be stimulated by maturation of the adrenal glands, called adrenarche. • Adrenarche: The maturation of the adrenal gland that takes place during adolescence • Changes in the brain system regulate the adrenal gland, which is also the system that controls how we respond to stress. • Cortisol: A hormone that is produced when a person is exposed to stress © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

8. What Triggers Puberty? (1) • Something in middle childhood reawakens the HPG axis and signals that the body is ready for puberty: • Presence of mature sexual partners • Sufficient nutritional resources • Physically healthy enough to begin reproducing © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

9. What Triggers Puberty? (2) • Onset of puberty is stimulated by certain brain chemicals: • Kisspeptin: A brain chemical believed to trigger the onset of puberty • Leptin: A brain chemical produced by the fat cells that may play a role in the onset of puberty through stimulating kisspeptin • Melatonin: A hormone secreted by the brain that contributes to sleepiness and that triggers the onset of puberty through its impact on kisspeptin Other factors influence onset of puberty: • Genes predispose onset at a certain age. • More fat cells and more exposure to light trigger puberty earlier. © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

10. How Hormones Influence Adolescent Development • Organizing Role • Prenatal hormones “program” the brain to develop in certain ways and according to a certain timetable (like setting an alarm clock). • Patterns of behavior as a result of this organization may not appear until adolescence (e.g., sex differences in aggression). • Activating Role • Increase in certain hormones at puberty activates physical changes (e.g., secondary sex characteristics). © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

11. Somatic Development • Effects of hormonal changes of puberty are remarkable. • Individual enters puberty looking like a child; within 4 years or so, has the physical appearance of a young adult. • The average individual grows about 10 in. taller, matures sexually, and develops an adult proportioned body. • The brain changes in size, structure, and function at puberty. © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

12. The adolescent growth spurt (1) • The simultaneous release of growth hormones, thyroid hormones, and androgens stimulates rapid gains in height and weight. • Adolescent growth spurt: The dramatic increase in height and weight that occurs during puberty • Peak height velocity: The point at when the adolescent is growing most rapidly • Epiphysis: The closing of the ends of the bones, which terminates growth after the adolescent growth spurt has been completed © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

13. The adolescent growth spurt (2) Figure 1.2: (a) Height (in centimeters) at different ages for the average male and female youngster. (b) Gain in height per year (in centimeters) for the average male and female youngster. Access the text alternative for slide images.

14. The adolescent growth spurt (3) • Body Dissatisfaction Among Adolescent Girls. Sex Differences in Muscle and Fat. • Increase in height is accompanied by increase in weight, which results from an increase in both muscle and fat. • End of puberty: Boys’ muscle-to-fat ratio is 3 to 1; girls’ ratio is 5 to 4. • Rapid gain in fat frequently prompts girls to become overly concerned about their weight. • Girls most susceptible to feelings of body dissatisfaction with their bodies are those who mature early and begin dating early. © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

15. Sexual Maturation (1) • Puberty brings a series of developments associated with sexual maturation. • Secondary sexual characteristics: The manifestations of sexual maturity at puberty, including the development of breasts, the growth of facial and body hair, and changes in the voice • Tanner stages: A widely used system that describes the five stages of pubertal development © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

16. Sexual Maturation (2) Table 1.1: The Sequence of Physical Changes at Puberty. Source: B. Goldstein, 1976.

17. Sexual Maturation: Boys Figure 1.3: The five pubertal stages for penile and pubic hair growth. (From Morris & Udry, 1980) Access the text alternative for slide images.

18. Sexual Maturation: Girls Figure 1.4: The five pubertal stages for breast and pubic hair growth. (From Marshall & Tanner, 1969) Access the text alternative for slide images.

19. Variations in the Timing and Tempo of Puberty • There is no specific average age at onset or duration of puberty. • There is no relation between the age at which puberty begins and the rate of pubertal development. • Ethnic differences exist in the timing and rate of pubertal maturation: • Black females mature (first); Mexican American females (second); white females (third). • Difference is probably not due to ethnic differences in income, weight, or area of residence. • Nonwhite girls may be exposed more often to chemicals that stimulate earlier puberty. © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

20. Genetic and Environmental Influences on Pubertal Timing Researchers who study variability in onset and timing of puberty use two approaches: • Study of differences among individuals • Study of differences among groups of adolescents Both types of studies point to both genetic and environmental factors. © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

21. Individual Differences in Pubertal Maturation Timing and tempo of puberty are largely inherited. • Genetic disposition is best thought of as an upper and lower age limit, not a fixed absolute. Two key environmental influences exist: nutrition and health. • Puberty occurs earlier among those who are better nourished. • Delayed puberty is more likely among individuals with a history of protein and/or caloric deficiency. • Chronic illness and excessive exercise also linked with delayed puberty. © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

22. Familial Influences on Pubertal Timing Social factors in the home environment may influence the onset of maturation, especially in girls. Early pubertal maturation in girls is related to several factors: • Father absent families, conflict-ridden households, having a stepfather, and sexual abuse • Tension in the family and stress, which affects hormonal secretion • The presence of a stepfather, which may expose the adolescent girl to pheromones that stimulate pubertal maturation • Pheromones: A class of chemicals secreted by animals that stimulate certain behaviors in other members of the species © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

23. Group Differences in Pubertal Maturation • These are typically studied by comparing average age of menarche. • Across countries, age at menarche occurs later when malnourished or suffering from chronic disease. • Median age range of menarche in Africa is 14–17, in the United States it is 12–13½. • Secular trend: The tendency, over the past two centuries, for individuals to be larger in stature and to reach puberty earlier, primarily because of improvements in health and nutrition © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

24. The Secular Trend Figure 1.5: The age at menarche has declined significantly over the past 150 years. This is known as the secular trend. Access the text alternative for slide images.

25. The Psychological and Social Impact of Puberty • Groups are compared at different stages of puberty: • Cross-sectional study: A study that compares two or more groups of individuals at one point in time • Longitudinal study: A study that follows the same group of individuals over time • A comparison of early versus late maturers is used when interested in the effects of pubertal timing on psychosocial outcomes. © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

26. The Immediate Impact of Puberty • Physical changes of puberty affect self-image, mood, and relationships with parents, whether puberty occurs early or late. • Puberty and Stress • Modest, but not overwhelming, stress early in life speeds the onset of puberty. • Maturing early may be stressful. • Going through puberty “on time” is generally not stressful. • Puberty and Effects on the Brain • Puberty affects the brain in ways that make people more vulnerable to stress. • Puberty makes the brain more malleable, or “plastic.” • Plasticity: The capacity of the brain to change in response to experience © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

27. Puberty and adolescent moodiness • Puberty and Adolescent Moodiness • Majority of teenagers do not report large ups and downs in their moods. • Change in mood is not solely due to hormones. • Greatly influenced by environmental factors such as shifts in activities. © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

28. Puberty and changes in patterns of sleep (1) • Many teenagers go to bed late in the evening and sleep late in the morning. • Delayed phase preference: A pattern of sleep characterized by later sleep and wake times, which usually emerges during puberty • Caused by interaction of biology and environment • One of most important factors: timing of secretion of melatonin shifts later • Environmental factors: internet, television, electronic media • Provide reason to stay up © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

29. Puberty and changes in patterns of sleep (2) • Early school schedule contributes to sleep deprivation. • Insufficient sleep can lead to the following: • Depression • Alcohol, tobacco, and drug use • Obesity • Cognitive impairment • Delinquency • Trying to catch up on weekends contributes to problems. © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

30. Puberty and changes in patterns of sleep (3) Figure 1.6: Children’s weekday and weekend bedtimes and wake times, by age. Access the text alternative for slide images.

31. Puberty and changes in patterns of sleep (4) Figure 1.7: The demands of school and extracurricular activities are taking their toll on adolescents’ sleep by keeping them busy into the late hours. Access the text alternative for slide images.

32. Puberty and Family Relationships • Puberty increases conflict and distance between parents and children, regardless of whether adolescent is early or late maturer. • Distancing effect is not consistently observed in ethnic minority families. • Research is inconclusive but increased conflict/distance could be due to changes in various changes in adolescents’ lives: • Hormones • Physical appearance • Psychological functioning © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

33. The Impact of Specific Pubertal Events • Most adolescents react positively to pubertal changes, especially secondary characteristics. • Reactions to menarche are less negative than in the past. • May be attributable to more information provided about menstruation • Link between negative attitudes and menstrual discomfort • Less is known about boys’ reactions to first ejaculations. • Usually not discussed by boys • Link between cultural differences in response to first ejaculation and views of masturbation © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

34. The Impact of Early or Late Maturation • Adolescents are aware of whether they are early or late relative to classmates. • Their feelings about themselves are influenced by comparisons. • Early maturers are likely to be “pseudomature.” • Perception of being an early or late maturer is more important in affecting one’s feelings than the reality. • Behavior is more closely related to how old the adolescent feels, not necessarily how physically mature they are. © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

35. Early Versus Late Maturation Among Boys • Pros of Early Maturation • Popularity • Better self-esteem • Cons of Early Maturation • More drug and alcohol use, delinquency, and precocious sexual activity • Greater impact of victimization/being bullied • Possibly elevated rates of depression and anxiety • More intense temper tantrums and depression during puberty © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

36. Effect of Maturation among Boys and Girls Figure 1.8: Boys who are more physically mature are less closely supervised by adults and spend more time hanging out with antisocial peers in settings in which delinquent behavior is more likely to occur. Access the text alternative for slide images.

37. Early Versus Late Maturation in Girls • Unlike boys, early maturing girls have more difficulties than their peers. • Poorer self-image • Higher rates of depression, eating disorders, and panic attacks • More often victims of rumors, gossip, and sexual harassment • One pro of early maturation for girls is more popularity. • Theories explaining why early maturation is harder on girls than boys • “Maturational deviance” hypothesis • “Developmental readiness” hypothesis • Cultural emphasis on desirability of thinness for females © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

38. Obesity and Eating disorders Weight gain sometimes results directly from physical changes of puberty. • Basal metabolism rate: The minimal amount of energy used by the body when resting • It drops about 15% in adolescence. • Normal weight gain and changes in body composition lead many adolescents to become concerned about weight. © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

39. Obesity (1) Many adolescents have legitimate concerns about being overweight. • Body mass index (BMI): A measure of an individual’s body fat, the ratio of weight to height, used to gauge overweight and obesity • Nearly 14% of U.S. adolescents are obese and another 16% are overweight. • By some estimates, the adolescent obesity epidemic will cost the United States more than $250 billion. • Increase in adolescent obesity has been especially dramatic among Black females. © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

40. Obesity (2) • Correlates and Consequences of Obesity • Interplay of genetic and environmental factors • Neurological factors: greater activation of reward centers, heightened responses to food, and poorer impulse control • Too much high-calorie, low-fiber food • Low activity levels • Obesity is especially prevalent among poor youth and among Black, Latinx, and Native American adolescents. • Psychological consequences vary across ethnic groups and gender. © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

41. Obesity (3) Figure 1.10: The percentage of adolescents who are overweight or obese has increased significantly. Access the text alternative for slide images.

42. Preventing and Treating obesity • Most of what children eat and drink comes from their homes. • Preventing obesity requires a multifaceted approach • Parents • Mass media • Food and beverage manufacturers • Restaurants • Schools • Communities • A combination of behavior modification and weight loss medication is more effective than either component by itself. • Fad diets actually increase, rather than decrease, obesity. © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

43. Anorexia Nervosa, Bulimia, and Binge Eating Disorder (1) • Only one fourth of American adolescents are highly satisfied with their bodies. • Over one half of adolescent girls consider themselves overweight and have attempted to diet. • Disordered eating: Mild, moderate, or severe disturbance in eating habits and attitudes • Studies of magazines aimed at women and adolescent girls reveal clear and consistent messages that women must be slim to be beautiful. © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

44. Anorexia Nervosa, Bulimia, and Binge Eating Disorder (2) • Some young women take drastic and dangerous measures to be thin. • Anorexia nervosa: An eating disorder found chiefly among young women, characterized by dramatic and severe self-induced weight loss • Bulimia:An eating disorder found primarily among young women, characterized by a pattern of binge eating and extreme weight loss measures, including self-induced vomiting • Binge eating disorder: An eating disorder characterized by a pattern of binge eating that is not accompanied by drastic attempts to lose weight • Only 1% of women develop anorexia, 1.5% of women develop bulimia, and 3.5% of women develop binge eating disorder. • Bulimia and anorexia are three times as common in females as in males. • Binge eating is about twice as prevalent among females. © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.

45. Anorexia Nervosa, Bulimia, and Binge Eating Disorder (3) Figure 1.11: Black females report more dieting and disordered eating than white females as preteens but less as young adults. Access the text alternative for slide images.

46. Body Dissatisfaction Figure 1.12: Body dissatisfaction by BMI classification for girls and boys. Access the text alternative for slide images.

47. Prevalence and causes of eating disorders (1) • Anorexia • Observed all over the world • Increased in prevalence over time • Consistent level of heritability across cultures • Bulimia • Observed mainly in Western cultures • Increased between 1970 and 1990 but has declined since (parallels levels of body dissatisfaction) • More culturally determined • Eating disorders are best understood as manifestations of a more general psychological problem called “internalized distress.” © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.