New insights on the illusory truth effect: societal reach, cognitive foundations, and mitigation strategies

Decades of research show that repeated information is more believed than new information – an “illusory truth effect”. This article integrates past and recent research to examine its broader social consequences. Findings indicate that repetition strengthens stereotypical beliefs about social groups and reduces moral condemnation. Moreover, the effect extends beyond message content: communicators conveying repeated messages gain credibility. Turning to underlying mechanisms, the review shows that simply knowing that information has been repeated can increase its perceived truthfulness, suggesting repetition acts as a learned cue for truth. Nonetheless, people underestimate the influence of repetition on beliefs, particularly on themselves. Importantly, the article identifies a key boundary condition: changing the informational ecology from affirmation to interrogation substantially weakens the effect. Together, these findings position repetition as a powerful force in belief formation and clarify the origins and the limits of repetition-induced truth. Implications within and beyond the illusory truth literature are discussed.