Dissociation des difficultés dans la tâche de sélection de Wason
Christian George · L’Année psychologique · 1990
Summary : Dissociation of difficulties in the Wason selection task. It is assumed that the Wason selection task is difficult to solve because it cumulates at least three difficulties. The first one concerns the information that is judged just sufficient to evaluate the conditional rule when both faces of cards are known. The second difficulty concerns the early choice, before any feedback, of the cards needed in order to obtain information that is sufficient to evaluate the rule, whatever the truth of this rule. The last difficulty concerns the identification of specific cards among the cards displayed, given that only one side is visible and that a sought-after property may be on the hidden side of one or several cards. Three experiments with students as subjects were conducted in order to disentangle these difficulties. In the first experiment cards were presented one by one with both faces indicated. Half of the subjects considered that the conditional rule is falsified by the first card to occur with p & not-q (or not-p & q), or that this rule is confirmed only when they have seen all the cards without finding any counter-examples. In the second experiment subjects had the opportunity to specify the cards needed without selecting them among cards displayed with a hidden face. About one third of the subjects mode correct choices. In the last experiment subjects where asked to select the card(s) that might thave a p on the hidden side. Only a quarter of them gave the correct answer. Key-words : reasoning, conditional, hypothesis testing.