born June 17, 1919, Minneapolis, Minn., U.S.
U.S. psychologist.
He worked with B.F. Skinner on instrumental learning in the 1940s, and in 1950 he introduced stimulus sampling theory (SST), a model for describing learning mathematically. He taught at Stanford, Rockefeller, and Harvard universities, among others. Estes's later work focused on "cognitive architectures." His works include Learning Theory and Mental Development (1970), Statistical Models in Behavioral Research (1991), and Classification and Cognition (1994). In 1997 he received the National Medal of Science.