Data selection and natural sampling: probabilities do matter

Probabilistic accounts of Wason's selection task (Oaksford & Chater, 1994, 1996) are controversial, with some researchers failing to replicate the predicted effects of probability manipulations. This paper reports a single experiment in which participants sampled the data naturally-that is, sequentially. The proportions of possible data types (i.e., cards in the selection task) also reflected the probability manipulation. Other than this procedural difference, the materials were the same as those in Oberauer, Wilhelm, and Rosas-Diaz's (1999) Experiment 3, which failed to show probabilistic effects. Significant probabilistic effects were observed. Moreover, in a comparative model-fitting exercise, a revised version of the information gain model (Hattori, 1999, 2002; Oaksford & Chater, in press-b) was shown to provide better fits to these data than did competing explanations.