Age, Psychology of

a branch of psychology in which the development of the human psyche and its traits at various age levels are studied.

As a separate branch of psychological science, the psychology of aging began to take shape in the middle of the 20th century; it includes child psychology, the psychology of the individual development of the adult human being, and gerontopsychology. However, the first research studies in the field of the psychology of aging had already begun by the end of the 19th century when, under the influence of C. Darwin’s theory of evolution, child psychology began to be firmly established. The psychophysiology of aging and of old age has taken shape from the development of geronto-psychology and geriatrics. The need to solve the practical problems of instructing adults, as well as the study of theoretical problems concerned with the development of the psyche, has led to the specific study of the phases of the psychological evolution of the adult human being.

The principal methods of obtaining knowledge concerning the age characteristics of the human psyche are the so-called cross-sectional and longitudinal methods of study. The first of these consists of studying large groups of persons of various ages in order to obtain comparative data on the psychological traits of each age. The second method consists of the prolonged study (lasting years and decades) of the same experimental subjects in order to keep track of the age changes in their psyches. The discovery of the levels of psychological development, different in kind with each person, and the determination of the age boundaries between each level are extremely complex tasks, since psychological age is not a simple function of the number of years which a person has lived.