CHAPTER 11 Adolescence: Physical and Cognitive Development

Puberty: 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

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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 20 th 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

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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

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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

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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 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

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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: Piaget

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s Stage of Formal Operations

Piaget

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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 ” than “ what is ” .

rather • 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 ” formal operations stage as a factor a part of • 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 in 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 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

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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 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 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

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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