EVALUATING NEGATIVE TESTS AND REFUTATIONS IN A RULE DISCOVERY TASK

Subjects participating in Wason's rule discovery task (1960) overwhelm ingly try to confirm rather than refute their currently held hypothesi s. Such a strategy is often inadequate and runs counter to the canons of scientific methodology. The present study was designed to investiga te subjects' differential evaluation of test strategies and outcome. O ne-hundred and sixty students participated in two experiments in which they had to judge someone else's potential test items in Wason's task . Experiment 1 demonstrated that exposure to various histories has a m ediating effect on the strength of the confirmation bias. In Experimen t 2, subjects knew the researcher's rule and thus whether each propose d test item would lead to confirmation or refutation of the hypothesis under consideration. The preferred items were those that alerted the subject to an incorrect hypothesis (refutation) and those that turned out to be positive instances of the rule sought after, with the combin ation of the two (a negative test leading to refutation) being most hi ghly evaluated.