Psychonomic Bulletin & Review

, Volume 26, Issue 5, pp 1705–1710 | Cite as

Repetition increases perceived truth equally for plausible and implausible statements

  • Lisa K. FazioEmail author
  • David G. Rand
  • Gordon Pennycook
Brief Reports


Repetition increases the likelihood that a statement will be judged as true. This illusory truth effect is well established; however, it has been argued that repetition will not affect belief in unambiguous statements. When individuals are faced with obviously true or false statements, repetition should have no impact. We report a simulation study and a preregistered experiment that investigate this idea. Contrary to many intuitions, our results suggest that belief in all statements is increased by repetition. The observed illusory truth effect is largest for ambiguous items, but this can be explained by the psychometric properties of the task, rather than an underlying psychological mechanism that blocks the impact of repetition for implausible items. Our results indicate that the illusory truth effect is highly robust and occurs across all levels of plausibility. Therefore, even highly implausible statements will become more plausible with enough repetition.


Truth Repetition Illusory truth Plausibility 


Author note

We gratefully acknowledge funding from the Ethics and Governance of Artificial Intelligence Initiative of the Miami Foundation and the Social Sciences and Humanities Research Council of Canada.

Open practices statement

The data, materials, and preregistration for Study 2 are available at


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Copyright information

© The Psychonomic Society, Inc. 2019

Authors and Affiliations

  • Lisa K. Fazio
    • 1
    Email author
  • David G. Rand
    • 2
  • Gordon Pennycook
    • 3
  1. 1.Department of Psychology and Human DevelopmentVanderbilt UniversityNashvilleUSA
  2. 2.Sloan School and Department of Brain and Cognitive SciencesMassachusetts Institute of TechnologyCambridgeUSA
  3. 3.Hill/Levene Schools of BusinessUniversity of ReginaReginaCanada

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