How explicit warnings reduce the truth effect: A multinomial modeling approach

The finding that repeating a statement typically increases its perceived truth has been referred to as the truth effect. Previous research has found that warning participants about the truth effect can successfully reduce, but not eliminate the effect. We used a multinomial modeling approach to investigate how warnings affect the cognitive processes that are assumed to underlie judgments of truth. In a laboratory experiment (N = 167), half of the participants were warned about the truth effect before judging the truth of repeated and new statements. Importantly, whereas half of the presented statements were of relatively unknown validity, participants could likely identify the correct truth status for the other half of the statements by drawing on stored knowledge. Multinomial modeling analyses revealed that warning instructions did not affect the retrieval of knowledge or participants' guessing behavior relative to a control condition. Instead, warned participants exhibited a significantly reduced tendency to rely on experiential information such as processing fluency when judging a repeated statement's truth. However, this was only the case for statements for which participants held relevant knowledge. These results are consistent with the notion that it is possible to discount metacognitive experiences such as processing ease when their informational value is questioned. Specifically, our findings suggest that people are less likely to base their judgments of truth on experiential information and metacognitive experiences induced by repetition if (a) they are warned about the deceptive power of repetition, and (b) other valid cues are available to inform their judgments.