Piaget, Jean (zhäNpyäˈjā) [key], 1896–1980, Swiss psychologist, known for his research in developmental psychology. After receiving a degree in zoology from the Univ. of Neuchâtel (1918), Piaget's interests shifted to psychology. He studied under C. G. Jung and Eugen Bleuler in Zürich, and then in Paris at the Sorbonne. There, he worked with Alfred Binet in the administration of intelligence tests to children. In reviewing the tests, Piaget became interested in the types of mistakes children of various ages were likely to make. After returning to Switzerland in 1921, Piaget began to study intensively the reasoning processes of children at various ages. In 1929, he became professor of child psychology at the Univ. of Geneva, where he remained until his death, also serving as professor of psychology at the Univ. of Lausanne (1937–54). Piaget theorized that cognitive development proceeds in four genetically determined stages that always follow the same sequential order. Although best known for his groundbreaking work in developmental psychology, Piaget wrote on a number of other topics as well. Influenced by the French anthropologist Claude Lévi-Strauss, Piaget's Structuralism (1970) focused on the applications of dialectics and structuralism in the behavioral sciences. He also attempted a synthesis of physics, biology, psychology, and epistemology, published as Biology and Knowledge (1971). A prolific writer, Piaget's writings also include The Child's Conception of the World (tr. 1929), The Moral Judgment of the Child (tr. 1932), The Language and Thought of the Child (tr. of 3d ed. 1962), Genetic Epistemology (tr. 1970), and The Development of Thought (tr. 1977).
See studies by H. Gardner (1973, repr. 1981), G. Butterworth (1982), S. Sugarman (1987), and M. Chapman (1988).