114 ChapTer 3 Development Over the Life Span
adolescent years sometimes overwhelm rational decision making
and why teenagers often behave more impulsively than adults.• Most American adolescents do not go through extreme emo-
tional turmoil, anger, plummeting of self-esteem, or rebellion.
However, conflict with parents, mood swings and depression,
and reckless or rule-breaking behavior often increase. The peer
group becomes especially influential, which is why peer bully-
ing is often the source of teenagers’ greatest unhappiness. Boys
tend to externalize their emotional problems in acts of aggres-
sion and other antisocial behavior; girls tend to internalize their
problems by becoming depressed or developing eating disorders.
adulthood
• Erik H. Erikson proposed that life consists of eight stages, each
with a unique psychological challenge, or crisis, that must be
resolved, such as an identity crisis in adolescence. Erikson iden-
tified many of the essential concerns of adulthood and showed
that development is a lifelong process. However, psychological
issues or crises are not confined to particular chronological peri-
ods or stages.
• When most people in an age group go through the same event
at about the same time, transitions are easier than when people
feel out of step. In industrialized nations, major demographic
changes have caused young adults to postpone the timing of
career decisions, marriage or commitment to a partner, and
parenthood. Many people between the ages of 18 and 25, es-
pecially if they are not financially independent, find themselves
in a phase between adolescence and adulthood called emerging
adulthood.
• The middle years are generally not a time of turmoil or crisis
but the prime of most people’s lives. In women, menopause be-
gins in the late 40s or early 50s. Many women have temporary
physical symptoms, but most do not regret the end of fertility or
become depressed and irritable. In middle-aged men, hormone
production slows down and sperm counts decline; fertility con-
tinues, but with increased risk of fetal abnormalities.
• Gerontologists have revised our ideas about old age because so
many people are living longer and healthier lives and are enter-
ing an extended phase of “positive retirement.” During old age,
the speed of cognitive processing slows down, and fluid intel-
ligence parallels other biological capacities in its eventual de-
cline. Crystallized intelligence, in contrast, depends heavily on
culture, education, and experience, and it tends to remain stable
over the life span.
• Many supposedly inevitable results of aging, such as senility,
depression, and physical frailty, are often avoidable. They may
result from malnutrition and overmedication, inactivity, and lack
of meaningful activities. Exercise and mental stimulation pro-
mote cognitive abilities in the human brain, even well into old
age, although some mental losses are inevitable.The Wellsprings of resilience
• Children who experience violence or neglect are at risk of many
problems later in life, but most children are resilient and are
able to overcome early adversity. Psychologists now study not
only the sad consequences of neglect, poverty, and violence but
also the reasons for resilience under adversity.Psychology in the news, revisited
• The findings that the adolescent brain does not reach maturity
until the 20s raise questions about whether teenagers who com-
mit crimes and other impulsive acts should be considered “less
guilty by reason of adolescence.”Taking Psychology With You
• Many child-rearing experts claim to have the one right way to
make children smarter, nicer, and more successful. Research in
child development can help people think critically about such
claims and also offers some general guidelines: Set high but re-
alistic expectations, explain the reasons for your rules, encourage
empathy, and reward good behavior.