Limits of the illusory truth effect for social-political opinions: Evidence from two experiments and a mini meta-analysis

Repeated exposure to information often increases its perceived truthfulness, a phenomenon known as the illusory truth effect. Although this effect is well established for factual statements, it remains unclear whether repetition similarly influences truth judgments for evaluative opinion statements. The present research tested whether repetition affects subjective truth judgments for social political opinion statements and whether this effect differs depending on participants’ level of agreement with the statements. Across two preregistered experiments (N = 457), participants were exposed to novel and repeated opinion statements and provided truth and agreement ratings either during encoding (Experiment 2) or at separate stages (Experiment 1). We evaluated repetition effects both overall and separately for statements participants agreed with, disagreed with, or rated as neutral. Across both experiments, repetition did not reliably increase truth judgments for social political opinion statements. Equivalence tests indicated that any repetition effects were smaller than a predefined smallest effect size of interest. This pattern was consistent across agreement categories, with no evidence of meaningful repetition effects for statements participants agreed with, disagreed with, or evaluated as neutral. A mini meta-analysis combining the present findings with prior work further supported the conclusion that repetition effects for opinion statements are negligible within the tested bounds. These findings suggest that repetition-based increases in perceived truth may not readily generalize to social political opinions. More broadly, the results constrain the conditions under which fluency-based processes influence truth judgments, indicating limited transfer to domains characterized by subjective or evaluative content.