Cognitive dissonance - Wikipedia en.wikipedia.org/wiki/Cognitive_dissonancePrivate View Founder. Leon Festinger, born in 1919 in New York City, was an American social psychologist whose contributions to psychology include the cognitive dissonance theory, social comparison theory, and the proximity effect.. Festinger graduated from the City College of New York in 1939; he then received his PhD in Child Psychology from the University of Iowa.