Truth by Repetition… Without Repetition: Testing the Effect of Instructed Repetition on Truth Judgments

Past research indicates that people judge repeated statements as more true than new ones. An experiential consequence of repetition that may underly this “truth effect” is processing fluency: Processing statements feels easier following their repetition. In three preregistered experiments (N = 684), we examined the effect of merely instructed repetition (i.e., not experienced) on truth judgments. Experiments 1–2 instructed participants that some statements were present (vs. absent) in an exposure phase allegedly undergone by other individuals. We then asked them to rate such statements based on how they thought those individuals would have done. Overall, participants rated repeated statements as more true than new statements. The instruction-based repetition effects were significant but also significantly weaker than those elicited by the experience of repetition (Experiments 1 and 2). Additionally, Experiment 2 clarified that adding a repetition status tag in the experienced repetition condition did not impact truth judgments. Experiment 3 further showed that the instruction-based effect was still detectable when participants provided truth judgments for themselves rather than estimating other people’s judgments. We discuss the mechanisms that can explain these effects and their implications for advancing our understanding of the truth effect.