German and American psychologist, one of the founders of Gestalt psychology, together with Max Wertheimer and Kurt Koffka. In studies of intelligence, the chimpanzee showed that the basis of problem solving by primates is not a mechanical alternation of trial and error, but a holistic assessment of the relationships within a problem situation (insight introduced this concept). In his work “On Physical Gestalts at Rest and in a Stationary State” (1920), he considered the processes of dynamic self-regulation of such systems as electrolytic solutions, and came to the conclusion that such processes also explain biological and psychological phenomena (the principle of “triple isomorphism”).