Adolescence, 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.
II 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 oestrogen in females, substances also associated with the appearance of secondary sex characteristics: facial, body, and pubic hair and a deepening voice in males; pubic and body hair, enlarged breasts, and broader hips in females. Physical changes may be related to psychological adjustment; some studies suggest that earlier-maturing individuals are better adjusted than their later-maturing contemporaries.
III 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.
IV 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 per cent of adolescents under the age of 15 and 75 per cent under the age of 19 reports 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 diseases. Consequently, the rate of illegitimate births and the incidence of venereal disease are increasing.
V 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. The German-born American psychologist Erik Erikson sees development as a psychosocial process going on through life.
The psychosocial task of adolescence is to develop from a dependent to an independent person, whose identity allows the person to relate to others in an adult fashion (intimacy). The occurrence of emotional problems varies among adolescents.