Repetition increases perceived truth equally for plausible and implausible statements
Abstract: 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 illusory truth effect is largest for ambiguous items, but this is due to the psychometric properties of the task, not 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 repetition.