Vera Aronson · CC BY-SA 3.0

Elliot Aronson conducted foundational experiments on cognitive dissonance and invented the Jigsaw Classroom, a cooperative-learning technique designed to reduce prejudice between students by making them depend on each other to master material. He is the only person in the American Psychological Association's 120-year history to win its top awards for writing, teaching, and research alike. His 1972 textbook The Social Animal introduced what he called Aronson's First Law: 'People who do crazy things are not necessarily crazy.'