theory of information processing and personality types. It is distinguished by its information model of the psyche (called "Model A") and a model of interpersonal relations. It incorporates Carl Jung's work on "Psychological Types" with Antoni Kępiński's theory of information metabolism. Socionics is a modification of Jung's personality type theory that uses eight psychic functions, in contrast to Jung's model, which used only four. These functions are supposed to process information at varying levels of competency and interact with the corresponding function in other individuals, giving rise to predictable reactions and impressions—a theory of intertype relations. In contrast to the generally accepted views in science on age-related variability of the human psyche, socionics postulates the presence of 16 psychological types unchanged throughout life. The issue of the existence of personality types is considered by modern science to be extremely controversial.