Teaching Bayesian reasoning in less than two hours

The authors present and test a new method of teaching Bayesian reasoning, s omething about which previous teaching studies reported little success. Bas ed on G. Gigerenzer and U. Hoffrage's (1995) ecological framework, the auth ors wrote a computerized tutorial program to train people to construct freq uency representations (representation training) rather than to insert proba bilities into Bayes's rule (rule training). Bayesian computations are simpl er to perform with natural frequencies than with probabilities, and there a re evolutionary reasons for assuming that cognitive algorithms have been de veloped to deal with natural frequencies. In 2 studies, the authors compare d representation training with rule training; the criteria were an immediat e learning effect, transfer to new problems, and long-term temporal stabili ty. Rule training was as good in transfer as representation training, but r epresentation training had a higher immediate learning effect and greater t emporal stability.