Transcript The Nature of Adolescence - FacultyWeb Support Center

CHAPTER 9
Physical and Cognitive
Development in
Adolescence
The Nature of Adolescence
•Adolescence is a transitional period with
continuity and discontinuity with childhood
•Not just a time of rebellion, crisis, pathology,
and deviance
•More accurately, it is of a time of evaluation,
decision making, commitment, finding a
place in the world
•Ethnic, cultural, gender, socioeconomic, age,
and lifestyle differences influence the actual
life trajectory of every adolescent
The Nature of Adolescence
•Adolescents are exposed to complex options
through the media
•They face the temptations of drug use and
sexual activity
•Too many adolescents are not provided with
adequate opportunities and support to
become competent adults
Puberty
•Puberty is not the same as adolescence
• most important marker of the beginning of adolescence
• puberty ends long before adolescence does
•Puberty -- period of rapid physical
maturation involving hormonal and bodily
changes
•Puberty is not a single, sudden event
• the most noticeable changes are signs of sexual maturation and
increases in height and weight
• Primary sex characteristics
• Secondary sex characteristics
Order of Male Pubertal Changes
•Increase in penis and testicle size
•Appearance of straight pubic hair
•Minor voice change
•First ejaculation (which usually occurs
through masturbation or a wet dream)
•Appearance of kinky pubic hair
•Onset of maximum growth in height and
weight
•Growth of hair in armpits
•More detectable voice changes
•Growth of facial hair
Order of Physical Changes in Females
•Breasts enlarge
•Pubic hair appears
•Hair appears in the armpits
•Height increases and hips become wider
than shoulders
•Menarche, first menstruation, irregular and
anovulatory
•Voice changes not comparable to males
•By the end, breasts become more fully
rounded
Weight and Height and the Growth Spurt
•Girls tend to outweigh boys early in
adolescence
•At the beginning of adolescence, girls tend
to be as tall as or taller than boys of their
age
•The mean age at the beginning of the
growth spurt in girls is 9 and for boys, the
mean age is 11
Hormonal Changes
•Hormones -- powerful chemical substances
secreted by the endocrine glands and carried
through the body by the bloodstream
•Puberty is an interaction of the
hypothalamus, the pituitary gland, and the
gonads
• Gonads -- the testes and ovaries -- are particularly important
Hormones
•Testosterone -- hormone associated in boys
with the development of genitals, an
increase in height, and a change in voice
•Estradiol is a type of estrogen
• in girls it is associated with breast, uterine, and skeletal development
•Testosterone and estradiol are present in the
hormonal makeup of both boys and girls
•The hormone-behavior link is complex
• Direct effects on emotions
• Indirect effects on emotions
Timing and Variations in Puberty
• The timing of puberty
• Sex, genes, and weight
• Menarche
• Spermarche
• The average age of menarche has declined significantly
since the mid-19th century
• Basic genetic program for puberty is wired into the species
• nutrition, health, and other environmental factors also affect puberty’s timing and
makeup
• Average age for the pubertal sequence to begin is between
10 to 13.5 for boys and 9 to 15 for girls
• Stress
• Too early – too late
Early and Late Maturation
•Adolescents who mature earlier or later than
their peers perceive themselves differently
•Early maturation in girls increases vulnerability
to problems
• more likely to smoke, drink, be depressed, have an eating disorder,
struggle for earlier independence from their parents, have older friends,
date, and earlier sexual experiences
Body Image
•Adolescents are preoccupied with their
bodies and develop images of what their
bodies are like
•Girls are less happy with their bodies and
have more negative body images than boys
throughout puberty
•Boys become more satisfied as they move
through puberty, probably because their
muscle mass increases
(Bearman & others, 2006)
Brain Development
•Adolescents’ brains undergo significant
structural changes
• corpus callosum -- thickens and this improves ability to process
information
• prefrontal cortex doesn’t finish maturing until 18 to 25 years of age or
later
• amygdala -- the seat of emotions such as anger -- matures earlier than
the prefrontal cortex
Adolescent Sexuality
•A time of sexual curiosity, exploration and
experimentation, of sexual fantasies and
realities, of incorporating sexuality into
one’s identity
Developing a Sexual Identity
•Involves learning to manage sexual feelings
(such as sexual arousal and attraction) and
developing new forms of intimacy
•Learning skills to regulate sexual behavior to
avoid undesirable consequences
•Sexual identity involves activities, interests,
styles of behavior, and an indication of
sexual orientation -- whether an individual
has same-sex or other-sex attractions
(Buzwell & Rosenthal, 1996)
The Timing of Adolescent Sexual
Behaviors
•The timing of sexual initiation varies by
country, gender, or socioeconomic
characteristics
•Many early adolescents are not emotionally
prepared to handle sexual experiences
• Early sexual activity is linked with risky behaviors such as drug use,
delinquency, and school-related problems
• Low parental monitoring was linked with early initiation of sexual
activity
Contraceptive Use
•Two kinds of risks accompany sexual activity:
• Unintended, unwanted pregnancy
• Sexually transmitted infections
•Both can be reduced significantly with
contraception use
•Many sexually active adolescents still do not
use contraceptives, or they use them
inconsistently
• Younger adolescents are less likely to take contraceptive precautions
Sexually Transmitted Infections
•Sexually transmitted infections (STIs) -infections contracted primarily through sexual
contact, including oral-genital and anal-genital
contact
• annually, more than 3 million American adolescents
• about one-fourth of those who are sexually experienced
(Centers for Disease Control and Prevention, 2008)
Adolescent Pregnancy
•United States has one of the highest
adolescent pregnancy and childbearing rates
in the industrialized world; however, recent
declines are noted
•Reasons for these recent declines include
increased contraceptive use and fear of
sexually transmitted infections such as AIDS
Risks of Becoming Pregnant as an
Adolescent
•Health risks for both the baby and the
mother
•Infants are more likely to have low birth
weight
•Infants have more neurological problems
and childhood illness
•Adolescent mothers often drop out of
school
•Even if they resume their education, they
generally never catch up economically
Characteristics
• Adolescent mothers are more likely to come from
low-SES backgrounds
• Many were not good students before they became
pregnant
• Some adolescent mothers do well in school and
have positive outcomes
• All adolescents can benefit from age-appropriate
family-life education
Issues in Adolescent Health
•Many of the behaviors that are linked to
poor health habits and early death in adults
begin during adolescence
•Early formation of healthy behavior
patterns, such as regular exercise and a
preference for foods low in fat and
cholesterol
• has immediate health benefits
• helps in adulthood to delay or prevent disability and mortality
Nutrition and Exercise
•The percentage of overweight teens in the
United States increased from the early 1990s
through 2004
•Compared to adolescents in 28 countries,
U.S. and British adolescents ate more fried
food and less fruits and vegetables
•U.S. boys and girls become less active as
they reach and progress through
adolescence
Nutrition and Exercise
• Adolescent boys are more likely to engage in
moderate to vigorous exercise than were girls
• Exercise is linked to a number of positive physical
outcomes
• Lower weight, reduced triglyceride levels, lower blood
pressure, a lower incidence of type II diabetes, lower drug
use
Sleep Patterns
•45 percent of adolescents studied got
inadequate sleep on school nights (fewer
than 8 hours)
• inadequate sleep resulted in feeling more tired or sleepy, cranky and
irritable, falling asleep in school, being in a depressed mood, and
drinking caffeinated beverages
• adolescents’ biological clocks undergo a shift as they get older; this
seems related to a delay in the nightly release of the sleep-inducing
hormone melatonin
(National Sleep Foundation, 2006)
Leading Causes of Death in Adolescence
• The three leading causes of death in adolescence are
accidents, homicide, and suicide
• More than half of deaths for ages 15 to 24 are due to
unintentional injuries; three-fourths involve motor
vehicles
• Homicide is the second-leading cause of death, especially
among African-American males
• The adolescent suicide rate has tripled since the 1950s
Substance Use and Abuse
• Proportions of U.S. students who used any illicit drug declined in the
late 1990s and first years of the 21st century
• The United States still has one of the highest rates of adolescent drug
use of any industrialized nation
• Early onset of drinking linked to increased risk of heavy drinking in
middle age
• Parents play a role in preventing drug abuse
• Peers also influence whether adolescents become substance abusers
• Gateway drugs
• Two explanations
(Johnston & others, 2010)
Anorexia Nervosa
•Anorexia nervosa -- eating disorder that
involves the relentless pursuit of thinness
through starvation
•Three main characteristics of anorexia
nervosa are:
• weighing less than 85 percent of what is considered normal for a
person’s age and height
• having an intense fear of gaining weight
• having a distorted image of one’s body shape
Bulimia Nervosa
•Bulimia nervosa -- eating disorder in which the
individual consistently follows a binge-andpurge pattern
• Bulimics go on an eating binge and then purge by self-inducing vomiting or
using laxatives
•Bulimics are preoccupied with food, have a
strong fear of becoming overweight, and are
depressed or anxious
The Formal Operational Stage
•According to Piaget, the fourth and final
stage of cognitive development, the formal
operational stage, begins in adolescence
•Formal operational thought is more abstract
and logical; full of idealism and possibilities
•Hypothetical-deductive reasoning involves
creating a hypothesis and deducing its
implications
Adolescent Egocentrism
•Adolescent egocentrism is the heightened selfconsciousness of adolescents
•David Elkind (1976) cited two key components:
• imaginary audience
• personal fable
•Adolescents also often show a sense of
invincibility or invulnerability
Information Processing
•Executive functioning involves higher-order
cognitive activities such as reasoning,
making decisions, monitoring thinking
critically, and monitoring one’s cognitive
progress
•Improvements in executive functioning
permit:
•more effective learning
•making decisions and engaging in critical
thinking
Decision Making and Critical Thinking
• Young adolescents are more likely to generate different options,
examine a situation from a variety of perspectives, anticipate the
consequences of decisions, and consider the credibility of sources
• The social context plays a role in adolescent decision making
• Cognitive changes that allow for improved critical thinking are:
• Increased speed, automaticity, and capacity of information
processing
• More benefits of content knowledge
• Increased ability to construct new combinations of knowledge
• Greater range and more spontaneous use of strategies or
procedures for applying or obtaining knowledge
School Issues
•Top-dog phenomenon -- moving from being
the oldest, biggest, and most powerful to
being the youngest, smallest, and least
powerful students (“The usual dip”)
• Consequence of moving from middle to high school
•U.S. high school dropout rates have declined
•Service learning -- form of education that
promotes social responsibility and service to
the community