Abstract: | Empirical investigations of conditional reasoning have generally found that both children and young adults perform poorly on tasks that require the selection or evaluation of those propositions that test the truth status of conditional statements (if p then q). Earlier work (D. O'Brien & W. F. Overton, Journal of Experimental Child Psychology 1980, 30, 44–60) suggested that poor performances with these tasks by young adults show improvement following the introduction of evidence that contradicts earlier faulty inferences, and this improvement generalizes to other conditional reasoning tasks. The effects of the contradiction training were not found with younger subjects. The present research is an extension of the contradiction training paradigm. Ten-, fourteen-, and eighteen-year-olds were tested to assess developmental differences in improvement with an evaluation and a conditional syllogism task. Significant improvement in performance was found for the twelfth grade students following the contradiction training, and this generalized across tasks. This effect was not found for the two younger groups. The usual poor performance of the oldest group is considered to be a false negative assessment of their conditional reasoning competency. Further, it is suggested that several correct performances of younger reasoners are false positive assessments of their conditional reasoning competency. |