in psychology, conceptual model of human behaviour developed by German American psychologist Kurt Lewin (Lewin, Kurt), who was closely allied with the Gestalt (Gestalt psychology) psychologists. Lewin's work went far beyond the orthodox Gestalt concerns of perception and learning; his theory emphasized an individual's needs, personality, and motivating forces. Although the former concentrated on the physiological aspects of human behaviour, Lewin treated psychology as a social science.

Lewin drew from physics and mathematics to construct his theory. From physics he (like the Gestaltists) borrowed the concept of the field, positing a psychological field, or “life space,” as the locus of a person's experiences and needs. The life space becomes increasingly differentiated as experiences accrue. Lewin adapted a branch of geometry known as topology to map the spatial relationships of goals and solutions contained in regions within a life space. His mathematical representation of life space also accounted for directions of pathways toward a goal and amount of attraction or repulsion toward a given object in the space. He also postulated that persons strive to maintain equilibrium with their environment; a tension (need) will stimulate locomotion (activity) to reinstate the equilibrium. Lewin adapted his field theory to the area of social psychology through his theory of group dynamics.