Wason selection task

Abstract: 'Is there any other point to which you would wish to draw my attention?' 'To the curious incident of the dog in the night-time.' 'The dog did nothing in the night-time.' 'That was the curious incident, ' remarked Sherlock Holmes. The quotation from A. Conan Doyle with which this book begins, is a delightfully appropriate summation of the authors' point of view garnered from their fifteen years of experiments on the psychology of reasoning. Dr. Wason and Dr. Johnson-Laird are intrigued by the extent to which most individuals can be considered naturally rational thinkers. They present here the surprising results of their comprehensive investigations of how humans draw explicit conclusions from evidence. Given a set of assertions, the authors write, to what extent can the individual appreciate all that follows from them by virtue of logic alone, and remain unseduced by plausible, but fallacious conclusions? We are not concerned with whether these assertions are true or false, nor with whether the individual holds them among his beliefs, nor with whether they are sane or silly. At the core of the Psychology of Reasoning is a vigorous discussion that incorporates various illustrations--some of them humorous, all of them fascinating--of the use of reason under a wide variety of different conditions. Particular emphasis is placed on the difficulties involved in dealing with negatively marked information that must be combined and used with other information for reaching conclusions. Thorough treatment is given as well to the search for plausible contexts that will render anomalous or ambiguous statements sensible. The authors have strived to isolate the components ofinference, the basic steps of any kind of deductive activity, in order to determine the psychological processes involved in them. What has been the outcome of this research? Dr. Wason and Dr. Johnson-Laird conclude, our research has suggested that the individual's logical competence may be either enhanced or limited by performance variables. And, of these, content has turned out to be vitally important for revealing, or obscuring structure. At best, we can all think like logicians; at worst, logicians all think like us.

Abstract: Human reasoning in hypothesis-testing tasks like P. C. Wason's (1968) selection task has been depicted as prone to systematic biases. However, performance on this task has been assessed against a now outmoded falsificationist philosophy of science. Therefore, the experimental data is reassessed in the light of a Bayesian model of optimal data selection in inductive hypothesis testing. The model provides a rational analysis (J. R. Anderson, 1990) of the selection task that fits well with people's performance on both abstract and thematic versions of the task. The model suggests that reasoning in these tasks may be rational rather than subject to systematic bias.

Abstract: A series of three experiments was conducted to examine the possible facilitating effect of thematic materials in Wason's selection task. The first two experiments attempted to replicate the major studies indicating such an effect. Experiment 1 failed to replicate the findings of Wason & Shapiro (1971), and the results of Johnson-Laird et al. (1972) were not replicated in Expt 2. In support of a memory-cueing hypothesis, improved performance was found in Expt 3 for an implication rule that was a part of our subjects' past experience. The present results are discussed both with respect to the other studies concerning the effect of thematic content in this task and in the context of a memory-cueing explanation for the thematic-materials effect.