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Summary: Adolescence, Adulthood and Aging

The stereotype of the rebellious adolescent is exaggerated, according to researchers. Among teenagers, the vast majority are not rebellious. Most hold values similar to their parents.

The environment of an adolescent affects the typical experiences of teenage years. Urban teens are more likely to get involved with gangs and antisocial activities. In the U.S., suburban teens often feel strong cooperative pressures. Rural teenagers may feel isolated and make plans to get away.

William James wrote that personality "sets like plaster" by the age of 30, and longitudinal research by psychologists suggests this is true for about 4 of 5 adults. The most stable trait of all is shyness.

Sometimes people change not because of individual factors but generational factors. From the 1960s into the 21st Century, birthrates have been falling and average age of first marriage has been rising in every developed country.

These generational changes have altered the character of early adulthood for many young people in developed countries. For many, the 20s are now a time of exploration rather than "settling down."

The changing role of women in developed countries has also altered adult life. Traditional roles are balanced with new realities caused by greater education for women and more participation by women in the workforce.

Intellectual strengths change with age. Old people are almost always at their peak in the morning hours. Young people are more likely to say they function better at night.

Young people excel at "flexible intelligence." They can learn new things more quickly than old people. Old people excel at "crystallized intelligence." They can use accumulated experience to solve problems.

Wisdom in old age requires healthy neurons in the brain. Neurons can continue to grow until people are in their 90s, if they are used, even though neurons of the central nervous system cannot be replaced after they die.

As people age, they lose skills and abilities that they do not exercise. When intellectual abilities are exercised continuously, people remain effective (and sometimes on the job) until they are in their 90s or over 100.

Write to Dr. Dewey at

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