Proceedings of the Annual Meeting of the Cognitive Science Society

A wide variety of judgment tasks have shown that once a reasoner favors a hypothesis, encountering evidence which contradicts it might not, in and of itself, dislodge that hypothesis. T h e interaction of prior belief and n e w evidence w a s studied in a covariation judgment task where subjects monitored multiple predictor-outcome relationships. Each relationship w a s programmed to reflect a strong positive contingency in a first phase, but in the second phase the contingency w a s negative, disconfirming the acquired expectation. For two of these relationships, the negative evidence w a s framed as positive evidence for alternative relationships, while in a third relationship, the negative evidence w a s not presented as supporting alternative explanations. Subjective contingency estimates indicated that the negative contingency w a s recognized in all three conditions. Belief perseverance, as measured by the likelihood of predicting the outcome on trials where the original predictor variable w a s present, w a s the strongest in the condition v^thout alternatives. These results support the notion that belief change is a function of the negative evidence pertaining to that belief and the presence of alternative explanations which seek their support from that same evidence.