1. Chapter Eight Rites of Passage: Physical and Cognitive Development in Adolescence

2. 8.1 Pubertal Changes: Learning Objectives What physical changes occur in adolescence that mark the transition to a mature young adult? What factors cause the physical changes associated with puberty? How do physical changes affect adolescents’ psychological development?

3. Signs of Physical Maturation Puberty consists of two changes that mark the change from childhood to young adulthood –Dramatic increases in height, weight, and changes in body’s fat and muscle content –Changes in the reproductive organs that mark sexual maturity, as well as secondary sexual characteristics (body and facial hair, growth of breasts)

5. During the adolescent growth spurt, females gain as much as 15 pounds a year and boys 17 pounds Girls begin the growth spurt about 2 years before boys Girls start the growth spurt at about age 11, peak at 12, and reach mature stature at 15 Boys begin at about 13, peak at 14, and reach mature stature at about 17 Head, hands, and feet grow first with trunk and shoulders last Physical Growth

7. Bones become denser and longer Muscle fibers become thicker and denser; heart and lung capacity increase –More so for boys Body fat increases –More so for girls Physical Growth (cont’d)

8. Brain Growth in Adolescence By the beginning of adolescence, the brain is 95% of adult size and weight Myelination and synaptic pruning are nearly complete Limbic system reaches maturity –Helps regulate reward, desire, pleasure, and emotional experiences Frontal cortex continues developing Combine to make adolescents more risky because desire swamps inhibition

10. VIDEO: Brain Development in Childhood & Adolescence

11. Sexual Maturation Primary sex characteristics are the organs of reproduction Secondary sex characteristics denote physical signs of maturity not directly linked to reproduction –Breasts and width of girls’ pelvis –Facial hair and broadening of shoulders in boys –Vocal changes in both Occur in a predictable sequence for girls and boys

12. Sexual Maturation (cont’d) Menarche is the onset of menstruation in girls (~13 years) –First cycles are usually irregular and without ovulation Spermarche is the first spontaneous ejaculation of sperm-containing fluid (also 13) –First ejaculations usually contain few sperm –Sufficient sperm to fertilize an egg may take months or years to develop

13. Mechanisms of Maturation The pituitary releases a growth hormone –Also stimulates other glands to produce estrogen in girls and testosterone in boys –Estrogen and testosterone are present in boys and girls but in different amounts Puberty’s timing is genetically regulated and is affected by health and nutrition Menarche occurs earlier in countries or SES levels where nutrition and healthcare are better Girls start menarche earlier when stressed (e.g., when mothers had harshly punished them or had stressful relationships themselves)

14. Mechanisms of Maturation (cont’d) Evolutionarily adaptive? –Parental investment theory: experiences with quality of fathering determine puberty’s timing Good fathers indicate males are invested in childcare, which delays puberty Bad fathers indicates males are not invested, which speeds up puberty on the chance of a good mate coming along Girls start menarche earlier when the father is –absent due to divorce –present, but psychologically distant or mentally “ill”

15. VIDEO: Premature Puberty

16. Psychological Impact of Puberty Body image –Girls are more critical of their appearance and are likely to be dissatisfied Especially when friends often discuss appearance –Boys are more likely to be pleased with appearance Most displeased when falling short of an idealized masculine body image Peers aren’t the source of displeasure

17. Response to Menarche and Spermarche Girls are moderately pleased by first menstruation, but irritated by its messiness –Usually share the news with mothers right away and later with friends –Traditional societies publicly celebrate menarche, but not industrialized ones Less is known about boys’ reactions to spermarche –Feel more positively if prepared for it (e.g., by reading) –Rarely tell parents and friends

18. Moodiness Rapid increases in hormones related to greater irritability and impulsivity, but not moodiness Adolescents are moodier than children or adults -They experience more changes in activities and social settings each day

20. Rate of Maturation Early maturer:11 (boys); 9 (girls) Late maturer: 15-16 (boys); 14-15 (girls) Especially in conflicted, impoverished homes, early-maturing girls often are –low in self-confidence –less popular –likelier to be depressed, show behavior problems, and smoke or drink –may feel pressured into sex, becoming teen moms less prestigious jobs & pay

21. Rate of Maturation (cont’d) Early maturation’s effects on girls’ sexual activity varies among U.S. ethnic groups –No effect for African Americans –European and Latin Americans 2x likelier to be sexually active –European Americans: friends who exert the pressure tend to have problem behavior and poor grades –Latinas: pressure comes mainly from older boys

22. Rate of Maturation (cont’d) Confusing results from different studies about early maturation’s effect on boys, who –dated more often and felt positive about their physical self and athletic abilities –found early or late maturation stressful (“off-time hypothesis”) –found puberty stressful regardless of timing Transition to puberty has fewer long-lasting effects for boys compared to girls

23. 8.2 Health: Learning Objectives What are the elements of a healthy diet for adolescents? Why do some adolescents suffer from eating disorders? Do adolescents get enough exercise? What are the pros and cons of participating in sports in high school? What are common obstacles to healthy growth in adolescence?

24. Nutrition High growth and metabolism rates require more calories for teens –Girls: ~2,200/day –Boys: ~2,700/day –Extra iron needed to produce hemoglobin boys (muscle mass) and girls (replace lost blood) need; both need calcium (bones) Most U.S. teens consume enough calories, but most are “empty” or too fatty Too little iron: listless & moody Too little calcium: risk of osteoporosis

25. Obesity Using BMI, 1 out of 6 teens are overweight, a number that has tripled in the past 25-30 years Overweight teens are unpopular, have low self-esteem, and put health at risk (e.g., high blood pressure, diabetes) When genes influence obesity, it is through effects on basal metabolic rate (speed of body burning off calories) TV affects eating via ads about tasty, fatty foods Parents affect eating habits by stressing external more than internal eating signals

26. Obese Youths Can Lose Weight Successful interventions focus on setting and monitoring goals about eating, exercise, and sedentary behavior Parents are trained to help set realistic goals and to use behavioral principles in meeting them Parents also trained to monitor their own lifestyles to avoid fostering child obesity Only 20% of programs work; after losing weight, many still are overweight Best to prevent rather than intervene

27. Anorexia & Bulimia Anorexia: eating disorder marked by an irrational fear of being overweight –Grossly distorted body image –About 15% of anorexic adolescents die Bulimia: eating disorder marked by binge eating and purging by vomiting or using laxatives –Bingeing occurs only a few times to as many as 30 times per week –Feel they cannot stop eating Most eating disordered are girls; 10% are boys

28. Risk Factors for Anorexia & Bulimia Female, low self-esteem, or anxiety disorders Genes regulating anxiety and food intake Having been a picky eater or pica disorder Biggest risk factors are being overly concerned about weight and a history of dieting –Peers and the media exacerbate these Overprotective parenting for anorexics and childhood obesity for bulimics Boys’ specific risk factors are childhood obesity, low self-esteem, pressure to lose weight; sports stressing being lean

29. VIDEO: Anorexia Nervosa

30. Physical Fitness Regular activity: 30 minutes of exercise, at least three times a week; pace should adolescent’s heart rate at ~140 beats/min Adolescents rarely get enough exercise Many adolescents engage in organized sports –Boys participate more than girls, although the gap is narrowing Sports have been shown to enhance self- esteem and initiative, as well as help learn about cooperation and teamwork

32. Physical Fitness (cont’d) Especially boys and younger students use steroids to enhance muscle size, strength, and recovery from injury –As many as 5-10% of boys use steroids –Can damage liver, reproductive system, skeleton, and cardiovascular system –Can lead to mood swings, aggression, and depression

33. Threats to Adolescent Well-Being Ethnic and gender differences in why 1/1,000 U.S. adolescents die/year -African-American boys die most often from firearms, whereas motor vehicle accidents (MVAs) account for most other boys’ deaths -Girls ’ deaths: most MVAs or natural causes -Death due to natural causes high in African Americans, but MVAs high in European Americans -Equal prevalence of naturally- or MVA-caused deaths, accounting for 2/3 of Latina-, and Asian- American girls’ deaths

34. Threats to Adolescent Well-Being (cont’d) Adolescents overestimate risky behaviors’ harmful potential Illusion of invulnerability: thinking others will be harmed, but not the self –Exists in adolescents and young adults –Ergo, cannot explain why adolescents are greater risk takers Adolescents more than young adults desire risk- associated rewards –Adolescents’ limbic system is more mature than their frontal cortex

36. 8.3 Information Processing during Adolescence: Learning Objectives How do working memory and processing speed change in adolescence? How do increases in content knowledge, strategies, and metacognitive skill influence adolescent cognition? What changes in problem-solving and reasoning take place in adolescence?

37. How Does Information Processing Improve in Adolescence? Adolescence is not a distinct stage for information-processing theorists This period is simply one in which rapidly changing childhood cognitive processes are “tweaked” to adult levels Changes do take place in certain areas of cognition

38. Working Memory & Processing Speed Speed of cognitive processing changes little after age 12 Adolescents’ working memory capacity is about the same as adults Their greater information-processing efficiency reflects increased axonal myelinization –Allows more rapid neural communication

40. Content Knowledge Adolescents are equally knowledgeable to adults in certain domains and more so in others (e.g., computers) This knowledge indirectly enables them to learn, understand, and remember more new experiences

41. Strategies and Metacognitive Skill Adolescents can now identify task-specific strategies and monitor how well they are implementing them –Outlining and highlighting text material –Creating a master study plan –Making lists of material they do vs. don’t know well

42. Problem-Solving and Reasoning Children use heuristics (rules of thumb), whereas adolescents are analytical and logical –Ex: I have descriptions of 40 kids; 30 only play football and 10 only do gymnastics. One person was described as skinny, jumps rope, and likes The Little Mermaid. Is this person a football player or gymnast? Children would say “gymnast”, attending to the concrete and stereotyped information More adolescents are likely to say “football player”, using the probability information

43. Problem-Solving and Reasoning (cont’d) Adolescents are skilled at finding weaknesses in arguments or flaws in reasoning Like adults, they sometimes use heuristics to find a “good enough,” effortless solution –Ex.: 2.2 x 2,027? Heuristic solution: 4,000 (2 x 2,000) Also like adults, their beliefs sometimes interfere with analytical, logical thought –Ex.: “The U.S. has the best legal system on earth, because it treats all justly”. Adolescent might cite examples of unjust trial outcomes.

45. 8.4 Reasoning about Moral Issues: Learning Objectives How do adolescents reason about moral issues? Is moral reasoning similar in all cultures? How do concern for justice and caring for other people contribute to moral reasoning? What factors help promote more sophisticated reasoning about moral issues?

46. Kohlberg’s Theory Level 1 - preconventional: punishment & reward –Stage 1: obedience to authority –Stage 2: nice behavior in exchange for future favors Level 2 - conventional: social norms –Stage 3: live up to others’ expectations –Stage 4: follow rules to maintain social order

47. Kohlberg’s Theory (cont’d) Level 3 - postconventional: moral codes –Stage 5: adhere to a social contract when it is valid –Stage 6: personal moral system based on abstract principles Individuals purportedly move progressively through the six stages –In sequential order only –Cannot skip stages

48. Support for Kohlberg’s Theory Longitudinal studies show that people do progress sequentially, do not skip stages Moral reasoning and moral behavior are linked However, moral reasoning is inconsistent across situations –Ex: A teen classified at the conventional level, sometimes reasons at the preconventional level Certain cultures do progress through the six- stage sequence, somewhat supporting his claim of universality

49. Cultural Differences in Moral Reasoning Some cultures do not stress individual rights and justice so central to Kohlberg’s theory –Hindus: stress caring and one’s duty to others Cultures espousing different moral principles may differently resolve moral dilemmas Kohlberg’s stages are not universal –His theory applies mainly to Western philosophical and religious traditions

50. Beyond Kohlberg’s Theory Carol Gilligan criticized Kohlberg’s theory as being geared to Western men, who stress a justice ethic –Western women stress the ethics of care Results show very small gender differences –Adolescents and adults of both genders will reason based on care or justice –The situation affects whether and which reason dominates

51. Promoting Moral Reasoning Being exposed to morally advanced behavior Open discussion of moral dilemmas with someone (e.g., parents) who reasons one stage higher –Especially helpful when the more advanced partner paraphrases the other’s viewpoint to highlight possible inconsistencies or other issues to consider Religious involvement and communities expose adolescents to caring people –May promote a sense of duty to others and concern for others –Think about it: correlation vs. causation?