Amos Tversky
Amos Tversky is one of the world's leading experts in judgment and human decision making. He is a cognitive psychologist who was a dominant figure in decision research and a leading psychological theorist, seriously challenged economic theory by showing that people frequently do not behave rationally to maximize their welfare. His work on the limits of human rationality also had a major impact on philosophy, statistics, political science, law, and medicine. His work had a great impact on economics because he tested hypotheses of rationality that are central to predicting how economies behave.
When he won a five-year MacArthur Foundation fellowship in 1984, Tversky said with typical modesty that much of what he had studied was already known to "advertisers and used car salesmen." His theoretical modeling and carefully designed experiments, however, elucidated the basis for such phenomena as consumers getting upset if a store charged a "surcharge" for using a credit card but being pleased if a store offered a "discount" for paying with cash.