Reasoning strategy vs cognitive capacity as predictors of individual differences in reasoning performance

The dual strategy model posits that reasoners rely on two information processing strategies when making inferences: The statistical strategy generates a rapid probabilistic estimate based on associative access to a wide array of information, and the counterexample strategy uses a more focused representation allowing for a search for potential counterexamples. In this paper, we focused on individual differences in strategy use as a predictor of performance on four reasoning tasks: Belief bias, base rate neglect, conjunction fallacy, and denominator neglect. Predictions from the strategy use model were contrasted with predictions from Dual Process Theories, which suggest that individual differences in performance reflect variations in cognitive ability. In each of four studies, a large number (N ≈ 200) completed one of the above reasoning tasks, a strategy use diagnostic questionnaire, and measures of IQ, cognitive reflection, and numeracy. In three of four studies, individual differences in strategy use predicted differences in reasoning performance when the effects of the other variables were eliminated. Bayesian analysis indicated that none of the individual differences measures predicted a significant portion of variance on the conjunction fallacy task, and that strategy use was a strong predictor on the remaining three tasks. This research suggests that the type of strategy that is adopted paves a road to successful reasoning that is independent of cognitive capacity.