ADOLESCENCE

Adolescence is the stage of maturation between childhood and adulthood. The term denotes the period from the beginning of puberty to maturity; it usually starts at about age 14 in males and age 12 in females. The transition to adulthood varies among cultures, but it is generally defined as the time when individuals begin to function independently of their parents.

Physical development
Dramatic changes in physical stature and features are associated with the onset of pubescence. The activity of the pituitary gland at this time results in the increased secretion of hormones, with widespread physiological effects. Growth hormone produces a rapid growth spurt, which brings the body close to its adult height and weight in about two years. The growth spurt occurs earlier among females than males, also indicating that females mature sexually earlier than males. Attainment of sexual maturity in girls is marked by the onset of menstruation and in boys by the production of semen. The main hormones governing these changes are androgen in males and estrogen in females, substances also associated with the appearance of secondary sex characteristics: facial, bodily, and pubic hair and a deepening voice among males; pubic and bodily hair, enlarged breasts, and broader hips among females. Physical changes seem to be related to psychological adjustment; studies suggest that earlier-maturing individuals are better adjusted than their later-maturing contemporaries.

Intellectual development
No dramatic changes take place in intellectual functions during adolescence. The ability to understand complex problems develops gradually. The French psychologist Jean Piaget determined that adolescence is the beginning of the stage of formal operational thought, which may be characterized as thinking that involves deductive logic. Piaget assumed that this stage occurs among all people regardless of educational or related experiences. Research evidence, however, does not support this hypothesis; it shows that the ability of adolescents to solve complex problems is a function of accumulated learning and education.

Sexual development
The physical changes that occur at pubescence are responsible for the appearance of the sex drive. The gratification of sex drives is still complicated by many social taboos, as well as by a lack of accurate knowledge about sexuality. Since the 1960s, however, sexual activity has increased among adolescents; recent studies show that almost 50 percent of adolescents under the age of 15 and 75 percent under the age of 19 report having had sexual intercourse. Despite their involvement in sexual activity, some adolescents are not interested in, or knowledgeable about, birth-control methods or the symptoms of sexually transmitted disease. Consequently, the rate of illegitimate births and the incidence of sexually transmitted disease are increasing.

Emotional development
The American psychologist G. Stanley Hall asserted that adolescence is a period of emotional stress, resulting from the rapid and extensive physiological changes occurring at pubescence. Studies by the American anthropologist Margaret Mead, however, showed that emotional stress is not inevitable, but culturally determined; she found that difficulties in the transition from childhood to adulthood varied from one culture to another. The German-born American psychologist Erik Erikson saw development as a psychosocial process going on throughout life. All three insights are valuable in their own way, but each adolescent shares a unique task: to develop from a dependent to an independent person who relates to others in a humane and well-socialized fashion.