Probability matching involves rule-generating ability: a neuropsychological mechanism dealing with probabilities

Probability matching is a nonoptimal strategy consisting of selecting each alternative in proportion to its reinforcement contingency. However, matching is related to hypothesis testing in an incidental, marginal, and methodologically disperse manner. Although some authors take it for granted, the relationship has not been demonstrated. Fifty-eight healthy participants performed a modified, bias-free probabilistic two-choice task, the Simple Prediction Task (SPT). Self-reported spurious rules were recorded and then graded by two independent judges. Participants who produced the most complex rules selected the probability matching strategy and were therefore less successful than those who did not produce rules. The close relationship between probability matching and rule generating makes SPT a complementary instrument for studying decision making, which might throw some light on the debate about irrationality. The importance of the reaction times, both before and after responding, is also discussed.