Logical knowledge and cue redundancy in deductive reasoning

This study clarified the basis of Hoch and Tschirgi's (1983) finding of good performance on abstract deductive reasoning problems based on Wason's (1966) four-card selection task. Different versions of the problem were developed through the addition of cues about antecedent-consequent relations redundant with the logical structure of the task. In all versions of the task, abstract symbols were used, and subjects were asked to test the truth or falsity of an implication rule. Twenty-five subjects from each of three education levels (high school, bachelor's, and master's) solved one of four versions of the task. Forty-eight percent of the master's subjects solved the original abstract version of the task compared to less than 10% of the high school and bachelor's subjects. When the problems contained redundant cues, performance improved dramatically, most notably in the bachelor's subjects. Reasoning performance seemed to be a function of both the general inferential abilities that subjects brought to the task and the redundant cues conveyed through problem content. Many of the master's subjects had adequate logical knowledge to solve the problems without the addition of redundant cues, though performance did increase when such cues were present. In contrast, high school subjects appeared to have so little understanding of the logical structure of conditionals that cue redundancy improved performance only slightly.