Henry W RieckenLeon Festinger (1919-1989) was a pioneering American social psychologist best known for formulating the theory of cognitive dissonance, one of the most significant concepts in twentieth-century psychology. A professor at the University of Minnesota, tanford University, and later the New School for Social Research, Festinger's work reshaped the study of belief, conformity, and social influence.Henry W. Riecken (1912-1992) was a sociologist and social psychologist whose research focused on social organisation and public opinion. He later served as president of the Social Science Research Council.Stanley Schachter (1922-1997) was a prominent social psychologist whose research extended into emotion, affiliation, and group processes. His later work at Columbia University contributed substantially to modern theories of emotion and social behaviour. Read More Read Less