Thesis

The Wason 4 card selection task: exploring the limits of human reasoning

The study of human reasoning has had an extensive history. From the time of Aristotle to the present, philosophers and psychologists have argued about the 'rationality' of man. For the past thirty years, the Wason selection task has been a major deductive reasoning research paradigm. In this task, participants are presented with a conditional statement and asked to select the appropriate cards to test the truth value of the conditional statement. While the task appears relatively simple, baseline performance is very poor. In an effort to explore the limits of human reasoning, the first experiment presented the standard version of the task in addition to manipulating two task conditions: (a) the familiarity of the stimulus materials (a deck of cards), and (b) the highlighting of the falsifying case. By forcing participants to focus on the falsifying case before attempting the selection task, performance was enhanced, but to a marginally statistically significant degree. However, allowing participants to gain greater familiarity with the cards did not appear to improve performance. Experiment 2 further investigated task conditions that may contribute to improved performance in the selection task. Specifically, this study looked at the effects of explicit rule violation information and cueing a falsification strategy. This results indicated that while accurate rule violation knowledge is essential to correctly solving this task, the majority of participants do not demonstrate adequate understanding of it. When participants are clearly informed about rule violation and they are cued to use a falsification strategy, performance is improved and they are less likely to use a confirmation bias in their problem strategy.

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