Intuitive predictions and judgements under uncertainty are often mediated by judgemental heuristics that sometimes lead to biases. Our micro-developmental study suggests that a presumption of rationality is justified for adult subjects, in so far as their systematic judgemental biases appear to be due to a specific executive-inhibition failure in working memory, and not necessarily to a lack of understanding of the fundamental principles of probability. This hypothesis was tested using an experimental procedure in which 60 adult subjects were trained to (...) inhibit the classical conjunction bias on a frequency judgement task derived from Tversky and Kahneman's work. Pre- and post-test performance was assessed via a probability judgement task. The data indicated a training effect, suggesting that subjects traditionally labelled as "irrational" with respect to the classical rules of inductive reasoning are in fact "inefficient inhibitors". These findings are discussed in terms of a polymorphous view of rationality. (shrink)

Decision-making literature has demonstrated that individuals’ preferences are strongly affected by the way in which choices are presented. This cognitive bias, termed the framing effect, is influen...

Using the matching bias example, the aim of the present studies was to show that adults' reasoning biases are due to faulty executive inhibition programming. In the first study, the subjects were trained on Wason's classical card selection task; half were given training in how to inhibit the perceptual matching bias (experimental group) and half in logic without the inhibition component (control group). On the pre- and post-tests, their performance was assessed on the Evans conditional rule falsification task (with a (...) negation in the antecedent of the rule), a task that also involves matching bias. In addition, subjects were tested for perceptual field dependence/independence using the Embedded Figures Test. The results brought out a specific inhibition training effect, as well as a clear-cut relationship in the experimental group between receptiveness to training and perceptual field independence. In the second study, the training paradigm was the same except that on the pre- and post-tests, the negation was in the consequent of the conditional rule (in this case, the perceptual matching response corresponds to the logical response). The subjects succeeded on the pre-test, and the matching-bias inhibition training had a negative effect on post-test performance. This specific negative priming effect confirms the inhibitory impact of our experimental training and outlines the dissociation of inhibition and logical components. (shrink)