1896-1980

Swiss psychologist who identified a universal sequence of four stages in the cognitive, linguistic, and social development of children, from egocentric, imitative, and concrete reaction to constructive, logical, and abstract thought. These stages are: (1) sensorimotor; (2) preoperational; (3) concrete operational; and (4) formal operational. Because teachers' understanding of these stages has been shown to affect students' progress, Piaget's theory of developmental psychology, "genetic epistemology," has had tremendous impact on educational philosophy and policy.