Positive and negative patterning in human causal learning

Investigations of patterning discriminations by nonhuman animals have gener ally found that positive patterning is easier to learn than negative patter ning. Studies of patterning discriminations in human causal learning tasks hare failed to document any differences between positive and negative patte rning. In the present study, human participants predicted an outcome on tri als involving either a compound cue or its elements. Positive and negative patterning problems mere successfully solved in a within-subjects design; n egative patterning problems proved to be more difficult when an additional, 50% contingent cue was included (Experiment 2), but not when it was exclud ed (Experiment 1). Possible reasons for these results are discussed. The di scussion concludes with an analysis of exemplar models (e.g., Pearce, 1994) of human causal learning and considers the conditions under which these mo dels do and do not anticipate our results.