A STUDY OF HUMAN DEDUCTIVE RESONING

Abstract

This study is based on the Wason selection task paradigm. Results from a random sample of 148 University undergraduates found that perception of biconditionality affected the choice of cards. The effect of phrasing permuted from the negator on responses was also found. This study also replicates past results on the high rate of endorsement of modus ponens, and low rates of tollens inference. However, this study differs from the standard Wason task in that six cards were used instead of four. The choice of four cards for the permission schema task was found to signifcantly increase because of this. This study also provided certain tasks with explicit information on problem spaces, but no difference was found when these tasks were compared with similar tasks without the provision of such information. Results here support the hypothesis that categorical antecedent and categorical consequent symbolic task produces the highest percentage of ponens and conformational blues, when compared to thematic tasks. This suggests that thematic tasks do not have such categorical relations in real life, where ambiguities and possibilities abound. It was found that the mental model theory of reasoning can account for this outcome. Overall, the thematic-arbitrary tasks produce even stronger matching tendencies than symbolic tasks. Matching apparently did not disappear with the framing of realistic and believable thematic tasks. This result supports the negative-processing account of matching, which posits that matching occurs because of difficulty in constructing contrast classes. Analyses of the thematic-arbitrary tasks show that a study of human reasoning also needs to take into account the semantics and pragmatics of thematic tasks, which are prone to invited inferences of various sorts. If such steps are not taken, the naive researcher would wrongly attribute matching status to instances where invited inferences lead to choice of cards which coincide with predictions made by the matching bias. This study also replicates previous results of facilitation for permission schema based task. Lastly, this study suggests that biconditionality in the Wason selection task is prevalent and inherent due to its visual task demands. A series of visual manipulations demanded for the selection task always invites a biconditional state of affairs. If value "A" and "B" are on either side of the one card, the subject may reason that another "A" or “B" card that he sees must have the other expected value ("B" and "A" respectively) that he bas earlier encountered. This study suggests some possible algorithms that subjects would use under a biconditional reading. Though researchers may dispute on whether subjects really employ algorithms, they nonetheless provide an explanation for choices of cards that hithero has been labelled as uninterpretable