Monetary incentives do not reduce the repetition-induced truth effect

Abstract

People rate and judge repeated information more true than novel information. This truth-by-repetition effect is of relevance for explaining belief in fake news, conspiracy theories, or misinformation effects. To ascertain whether increased motivation could reduce this effect, we tested the influence of monetary incentives on participants' truth judgments. We used a standard truth paradigm, consisting of a presentation and judgment phase with factually true and false information, and incentivized every truth judgment. Monetary incentives may influence truth judgments in two ways. First, participants may rely more on relevant knowledge, leading to better discrimination between true and false statements. Second, participants may rely less on repetition, leading to a lower bias to respond "true." We tested these predictions in a preregistered and high-powered experiment. However, incentives did not influence the percentage of "true" judgments or correct responses in general, despite participants' longer response times in the incentivized conditions and evidence for knowledge about the statements. Our findings show that even monetary consequences do not protect against the truth-by-repetition effect, further substantiating its robustness and relevance and highlighting its potential hazardous effects when used in purposeful misinformation.