Repeating statements increases source credibility

Repeating statements increases their perceived truth, a phenomenon known as the illusory truth effect. However, whether repetition also enhances the credibility of the source of those statements remains unclear. Across four preregistered experiments, we investigated a repetition-induced source credibility effect. In Experiment 1 (N = 90), participants were exposed to 20 unrepeated and 20 repeated statements communicated by 40 individuals. Repetition significantly increased both perceived statement truth and source credibility. Experiment 2 (N = 65) tested whether this increase generalizes to new contexts. After rating the truth of repeated and unrepeated statements paired with different sources, participants evaluated novel statements from the same sources—showing greater credibility for sources previously linked to repeated statements. Experiment 3 (N = 180) did not replicate the effect when initial truth ratings were omitted. However, Experiment 4 (N = 435) resolved this inconsistency, demonstrating a robust repetition-induced source credibility effect, independent of participants’ task during source–statement pairings. We discuss the implications of these findings for theories of illusory truth, persuasion, and communication management.