Does repetition increase perceived truth equally for conspiracy and trivia statements? A registered replication report

TL;DR

This study shows that repetition affects belief in conspiracy and trivia statements similarly when they are equally plausible.

Contribution

The study matches conspiracy and trivia statements on baseline plausibility to test the illusory truth effect.

Findings

Repetition similarly increases perceived truth for conspiracy and trivia statements when plausibility is matched.

The illusory truth effect is not unique to conspiracy statements when baseline plausibility is controlled.

Results suggest the effect of repetition on belief is consistent across statement types.

Abstract

Repetition increases the perceived truth of information. This illusory truth effect is a well-documented and robust phenomenon. Although research has primarily focused on trivia statements, the effects of repetition on belief have also been identified for consequential statements such as fake news headlines. Moreover, research reveals repetition increases accuracy ratings for conspiracy statements. However, in past work, the illusory truth effect was smaller for conspiracy statements than trivia statements. This result raises the intriguing possibility that there is something unique about conspiracy statements relative to trivia statements that makes them more resistant to the effects of repetition. However, this difference in the illusory truth effect between conspiracy and trivia statements may be due to differences in baseline plausibility rather than anything specific about conspiracy statements. Overall, the conspiracy statements were seen as less plausible than the trivia statements (both true and false trivia statements) in the prior experiment. In this registered report, we examined the illusory truth effect for conspiracy and trivia statements using the same procedure as in previous research, but we matched the statements on baseline plausibility. In line with our hypothesis, the effect of repetition on perceived truth was similar for conspiracy and trivia statements when they were equally implausible (or plausible). Results from this study replicate the generality of the illusory truth effect to statements that can cause harm and suggest that the psychological effect of repetition on truth ratings is equivalent for equally implausible (or plausible) conspiracy and trivia statements.

The online version contains supplementary material available at 10.3758/s13423-025-02836-w.

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