CHAPTER 11CHAPTER 11

Adolescence: Physical and Cognitive Adolescence: Physical and Cognitive DevelopmentDevelopment

Puberty: The Biological EruptionPuberty: The Biological Eruption

Puberty: The Biological Eruption

• Puberty– Stage of development characterized by reaching sexual maturity

and the ability to reproduce– Onset of adolescence coincides with advent of puberty

• Feedback loop– Hypothalamus signals the pituitary gland, which in turn releases

hormones that control physical growth and the gonads– Gonads respond to pituitary hormones by increasing production

of sex hormones– Sex hormones further stimulate the hypothalamus, perpetrating

the feedback loop

Puberty: The Biological Eruption (cont’d)

• Primary sex characteristics– Females: ovaries, vagina, uterus, and fallopian tubes– Males: penis, testes, prostate gland, and seminal vesicles

• Secondary sex characteristics– Breast development, deepening of the male voice, and the

appearance of facial, pubic, and underarm hair– Not involved in reproduction

The Adolescent Growth Spurt

GIRLS• Girls’ growth spurt at age 10

• Girls gain a little more than 13 inches in height; spurt in weight continues for 2 years after growth spurt begins

• Hips get wider due to having twice as much body fat as boys

• Girls’ body shape more rounded

BOYS• Growth spurt at age 12

• Peak reached 2 years later

• Gain 14 ½ inches in height

• Eventually boys become taller and heavier than girls

• Boys’ shoulders get broader

Fig. 11-1, p. 228

Fig. 11-2, p. 229

Asynchronous Growth

• Children who spurt earlier more likely to have longer torsos and shorter legs

• No significant differences between early and late sprouters in the total height at maturity

• Asynchronous growth– Different parts of the body grow at different rates– Hands and feet mature before the arms and legs do– Legs reach peak before shoulders and chest– Boys stop growing out of pants about a year before they stop

growing out of their jackets

The Secular Trend

• During the 20th century, children in the Western world grew more rapidly and wound up taller than children from earlier times.– Accompanied by an earlier onset of puberty– Known as a secular trend

• Occurrence of a secular trend in height and weight has been documented in nearly all European countries and the United States.

• Nutrition and medical advances contributed to height increase.

Fig. 11-3, p. 230

Changes in Boys

• Pituitary gland stimulates the testes to increase output of testosterone.– Leads to further development of male genitals

• First sign of puberty is accelerated growth of the testes, which begins at about 11½ years old.

• Testicular growth accelerates testosterone production and other pubertal changes.

• Penis begins a spurt of accelerated growth about a year later– Still later, pubic hair spurts

• Underarm and facial hair appears about age 15.

Changes in Boys (cont’d)

• Facial hair first appears on upper lip– Full shaving occurs in half of American boys at age 17

• Voice deepens at age 14 or 15 because of the growth of the “voice box” or larynx and the lengthening of the vocal cords.

• Testosterone triggers development of acne.– Boys more prone to acne

• Males have erections from infancy but not frequent until age 13 or 14, resulting in nocturnal emissions. – Wet dreams

Changes in Boys (cont’d)

• Mature sperm found in ejaculatory emissions by age 15– Ability to ejaculate precedes presence of mature sperm

• Half of all boys experience gynecomastia (enlargement of the breasts), which declines in a year or two.

• At 20 or 21, young men stop growing taller because testosterone causes epiphyseal closure, which prevents the long bones from making further gains in length.

Changes in Girls

• The pituitary gland signals the ovaries to vastly increase estrogen production at puberty.

• Estrogen may stimulate growth of breast tissue beginning at age 8 or 9 (breast buds).

• Breasts reach full size in about 3 years.– Mammary glands are not fully mature until a woman has a baby

• Estrogen also helps widening of pelvis and rounding of hips.

Changes in Girls (cont’d)

• At about age 11, girls’ adrenal glands produce small amounts of androgens that contribute to development of underarm and pubic hair.

• Estrogen causes the labia, vagina, and uterus to develop during puberty.– Androgens cause the clitoris to develop

• Vaginal lining varies in thickness according to the amount of estrogen in the bloodstream.

• Estrogen brakes the female growth spurt before the ending of the male growth spurt.

Menarche

• Menarche– First menstruation– Occurs between ages 11 and 14– Some girls as earlier as age 9; some as late as age 16 – Height-to-weight ratio contributes to age of menstrual cycle– Average triggering weight depends on the girl’s height– Early starting in Westernized countries has stabilized

Fig. 11-4, p. 232

Regulation of the Menstrual Cycle

• Estrogen and progesterone levels regulate the menstrual cycle.

• Ovulation typically begins 12 to 18 months after menarche.– Most menstrual cycles begin in the first two years or so after

menarche occurs without ovulation.– If ovulating, a ripe ovum is released by the ovary when estrogen

reaches peak blood levels.

• Average menstrual cycle is 28 days– Menstrual cycle irregular for first few years after menarche but

later assumes a regular pattern

Early Versus Late Maturers

• BOYS– Early-maturing boys tend to be more popular than late-maturing

boys and more likely the leaders in their school.– Some early-maturing boys engage in delinquency and

aggression as well as sexual encounters they may not be prepared for.

• GIRLS– Early-maturing girls tend to have lower self-esteem than male

counterparts.– Early-maturing girls are conspicuous with height and developing

breasts.• Even worse if development started in elementary school• May be teased for it and may get lower grades

Body Image

• Body image refers to how physically attractive we perceive ourselves to be and how we feel about our body.

• By age 18, girls and boys are more satisfied with their bodies than they were in their earlier teens.

• Adolescent females tend to be more preoccupied with body weight and slimness than adolescent males.

• Adolescent males may want to increase body mass.

Health in AdolescenceHealth in Adolescence

Causes of Death• Greatest causes of adolescent death

– Accidents, mostly with motor vehicles– Homicides– Suicides

• Death rates twice higher for males than females– Males take more risks

• Poor adolescents living in urban areas of high population at greatest risk of homicidal death– Homicide rates greater for African-American adolescents than

for European-American adolescents

Fig. 11-5, p. 211

Nutrition

• Average girl needs 1,800 to 2,400 calories per day; average boy needs 2,200 to 3,200 calories per day

• At peak of spurt, adolescents use twice as much calcium, iron, zinc, magnesium, and nitrogen as during the other years of adolescence.

• Irregular eating patterns contribute to adolescents’ nutritional deficits, especially skipping breakfast.

• More likely to obtain less vitamin A, thiamine, and iron but more fat, sugar, and sodium than recommended

Eating Disorders

• Due to slimming down of American ideal, girls are more prone to eating disorders

• Anorexia nervosa– Life-threatening eating disorder characterized by extreme fear of

being heavy, dramatic weight loss, a distorted body image, and resistance to eating enough to maintain a healthful weight

• Female-to-male ratio of anorexia is 10 to 1

• More affluent European-American females have body image issues.

Eating Disorders (cont’d)

• Females with anorexia– Drop 25% of their body weight within a year, resulting in

abnormalities in the endocrine system that prevent ovulation– General health declines– Every system in the body is affected, including respiratory and

cardiovascular systems– At risk for premature development of osteoporosis– Mortality rate is between 4% and 5%

• Distortion of body image is major feature of the disorder

• Anorexic woman sees self in mirror as too heavy

Bulimia Nervosa

• Bulimia nervosa– Cyclical binge eating and purging– May include strict dieting– Fasting, laxatives, and demanding exercise regime

• Tends to afflict women during adolescence and young adulthood

• Eating disorders connected with depression• Eating disorders run in families, indicating genetic

involvement; eating disorders tend to involve obsessionistic and perfectionistic personality traits

Cognitive Development: PiagetCognitive Development: Piaget’’s Stage s Stage of Formal Operationsof Formal Operations

Piaget’s Stage of Formal Operations

• Formal operations refers to the ability to abstract reason, classify objects, hypothesize, and formulate arguments.

• Top level of Piaget’s theory

• Adolescents have reached cognitive maturity in the formal operations stage.

• Formal operations can begin as early as 11 or 12 years old.

Hypothetical Thinking

• Adolescents develop concept of “what might be” rather than “what is”.

• Adolescents “try on” different clothes and attitudes to see which work best for them.

• Some may experience anxiety due to pressure to pick the best career fit.

Sophisticated Use of Symbols

• Solving mental activities with “x” as a factor a part of formal operations stage

• Ability to manipulate symbols a part of formal operations stage

• Adolescents can analyze metaphors in literature.

• Adolescents may take on “crystal clear” solutions to religious, political, and social issues without tolerance for other issues that may be contributory.

Adolescent Egocentrism

• Adolescents have difficulty sorting out issues that concern others from the things that concern themselves

• Imaginary audience– Adolescent placed at center stage of fantasies– Assumes others are concerned with their looks and dress– Explains why adolescents engage in looking in the mirror so

much

• Personal fable– Belief that one’s thoughts and emotions are unique and special– Normal for male adolescent to think he is indispensable– Reason STI’s occur – “Can’t happen to me”– Believe that no one has ever experienced the same things as

themselves

Gender Differences Gender Differences in Cognitive Abilitiesin Cognitive Abilities

Verbal Ability

• As a group, females surpass males in verbal ability.

• Boys in the U.S. are more likely to be dyslexic and read below grade level.

• Culture and heredity play a role in the mastery of verbal ability.

Visual-Spatial Ability

• Visual-spatial ability (VSB)– The ability to visualize objects or shapes and to mentally

manipulate and rotate them– Important ability in art, architecture, and engineering

• By age 8 or 9, boys begin outperforming girls in VSB.– Most notable on mental rotation tasks

• VSB ability of boys may be due to evolutionary factors as well as sex hormones.

• Environment plays a role – Ex.: toys for boys (Legos, Erector sets) versus the toys for girls– Boys engage in more sports, which is associated with better

performance of visual-spatial skills

Fig. 11-6, p. 239

Mathematical Ability

• Male adolescents generally outperform female adolescents especially in geometry and word problems.

• No sex differences in understanding math concepts at any age.

• Teaching expectations and involvement with math from dad contribute to mathematical advancement of boys; girls less likely to be encouraged in math; advanced teachers more likely male; teachers spend more time helping males with math

Moral DevelopmentMoral Development

Moral Development

• Many adolescents engage in postconventional moral reasoning.– They deduce proper behavior

• Postconventional moral reasoning based on person’s own moral standard and personal values– Stages 5 and 6

• Stage 5– Legalistic and contractual– Laws stem from agreed upon procedures; many rights have

great value and should not be violated

• Stage 6– Based on universal ethical principles of human life, individual

dignity, and reciprocity (behavior that is consistent with these principles is considered right)

Moral Behavior and Moral Reasoning

• Positive relationship between a person’s level of moral development and his or her behavior

• Group discussion of moral dilemmas elevates delinquents’ level of moral reasoning

Evaluation of Kohlberg’s Theory

• Evidence supports that moral judgment develops in children in upward sequence.

• Postconventional thought first found in adolescents; formal operational thinking a prerequisite

• Kohlberg underestimated the role of cultural, social, and educational institutions as well as parents.

• Postconventional thinking absent in developing countries and infrequent in the U.S.; e.g., principles such as freedom and tolerance of differences are not universally admired

The Adolescent in SchoolThe Adolescent in School

The Adolescent in School

• Adolescents are influenced by opinions of peers and teachers.– Self-esteem reflective of their skills

• Middle-school teachers more likely to exert more behavioral control than teachers in elementary school– Conflict arises

• Transition to middle and high school results in decline in grades and participation in school activities.– More difficult for girls due to puberty

• Drop in self-esteem and increase in psychological distress

• Schools can ease distress by creating a warmer climate and establishing schools within a school.

Dropping Out

• Early predictors– Below grade-level reading and excessive absences

• Other factors– Low SES, low grades, poor problem-solving ability, low self-

esteem, problems with teachers, dissatisfaction with school, substance abuse, being old for one’s grade level (retention is not the same as remediation), and being male

• Middle-class youth who feel bored with school, alienated, or strongly pressured to succeed are at risk.

Preventing Drop Out

• Successful prevention programs include – early preschool interventions– identification and monitoring of high-risk students– small class size, individualized instruction, and counseling– vocational components that link learning to community work

experiences– involvement of families or community organizations– positive school climate that provides clear and reasonable

educational goals, student accountability for behavior, and motivational systems that involve penalties and rewards

Adolescents in the WorkforceAdolescents in the Workforce

Prevalence of Adolescent Employment

• One-half of high school sophomores, two-thirds of juniors, and almost three-fourths of seniors have a job during the school year.

• 2 to 3 million adolescents work illegally.

• Employed lower-income adolescents work longer hours than working middle-class teens.

Pros and Cons of Adolescent Employment

• Potential benefits of employment include – developing a sense of responsibility, self-reliance, and discipline– learning to appreciate value of money and education– acquiring positive work habits and values– enhancing occupational aspirations

• Lower SES adolescents work to supplement family income.

• Middle-class teens use income for personal purchases, such as clothing, iPods, CDs, DVDs, gear, and car payments.

Pros and Cons of Adolescent Employment (cont’d)

• Most working teens in jobs with low pay, high turnover, little authority, and little chance of advancement; typically perform repetitive tasks.

• Teens working more than 11 to 13 hours per week have– lower grades, higher rates of drug and alcohol use, more

delinquent behavior, lower self-esteem, and higher levels of psychological problems than other students not working

• Working teens less monitored, spend fewer hours with family, and granted more decision-making power

• Hours worked per week needs to be limited