Proceedings of the Annual Meeting of the Cognitive Science Society

Subjects were presented with previously played Mastermind games in the form of "Mastermind problems". Although each problem was formally deduclble, and In some cases, overdetermined, subjects nevertheless usually failed to make more than a third of the potential deductions. A Bayesian model that treated the task as one of "probabilistic reasoning" rather than "logical deduction" accounted well for the performance of the lower performing subjects. It is argued that at least some of the reasoning failures seen on hypothesis evaluation tasks such as this one are produced in part by the solver's replacement of a "deduction" representation with a "probabilistic reasoning" representation.