Comparing the Role of Memory in the Illusory Truth Effect and Moral Repetition Effect

Recent findings show that expressing factual beliefs and moral beliefs is both influenced by prior exposure to the case at hand, suggesting that truth judgments and moral judgments may rely on similar cognitive processes. However, the empirical evidence so far suggests that this repetition effect is larger on truth judgments than on moral judgments. Plausible theoretical assumptions could be made for both similar or different underlying cognitive processes, leading to either similar or different effect sizes. In eight experiments, we first investigated whether the illusory truth effect and the moral repetition effect are similar in size when tested on identical materials. This was not the case: The truth effect was reliably larger than the moral repetition effect, suggesting that the underlying processes differ. Second, six experiments tested the role of memory for repeated information in both repetition effects. The results show that recognition of previously encountered information was related to truth judgments but not to moral judgments, which explained part of the difference in repetition effects. Moreover, memory for repeated information was better after truth judgments than after moral judgments, suggesting that individuals try to remember previously encountered information when expressing factual versus moral beliefs. Together these findings indicate that individuals draw on their past experiences when assessing truth but not when assessing morality. We discuss these results in terms of the malleability of judgments to external information.