Is Earth a Perfect Square? Repetition Increases the Perceived Truth of Highly Implausible Statements

Abstract

A single exposure to statements is typically enough to increase their perceived truth. This Truth-by-Repetition (TBR) effect has long been assumed to occur only with statements whose truth value is unknown to participants. Contrary to this hypothesis, recent research found a TBR effect with statements known to be false. Of note, a recent model even posits that repetition could increase the perceived truth of highly implausible statements. As for now, however, no empirical evidence has reported a TBR effect for highly implausible statements. Here, we reasoned that one may be found provided a sensitive truth measure is used and statements are repeated more than just once. In a preregistered experiment, participants judged the truth of highly implausible statements on a 100-point scale, and these statements were either new to them or had been presented five times before the judgment task. We observed a TBR effect: truth judgments were higher for repeated statements than for new ones - even if all statements were still judged as false. Exploratory analyses additionally suggest that all participants were not equally prone to this TBR effect: about half the participants showed no or even a reverse effect. Overall, the results provide direct empirical evidence to the claim that repetition can increase perceived truth even for highly implausible statements, although not equally so for all participants and not to the point of making the statements look true.

Truth by repetition … Without repetition: Testing the effect of instructed repetition on truth judgments.

“…Although this null effect might be due to participants' lack of knowledge, prior studies have shown that the experience of fluency is still used as a valid cue for truth when knowledge about statements' content (Fazio et al, 2015;Fazio et al, 2019), source credibility (Begg et al, 1992;Unkelbach & Stahl, 2009), and declarative advice about the credibility of a statement (Unkelbach & Greifeneder, 2018) suggest the opposite. This is also in a recent study that found a truth effect for highly implausible statements, such as "earth is a perfect square", for which knowledge (of falsity) is present (Lacassagne et al, 2021).…”

“…Similarly, Henderson et al (2021) found a negative TBR effect for about 15% of the sample. Moreover, Lacassagne et al (2022) found that when the to-be-judged statements are selected to be highly implausible, the proportion of participants showing a negative TBR effect increased to 28%. Our findings extend this idea in that we showed that the negative TBR effect was more likely for instructed (40%) than experienced (20%) repetition.…”

Truth by Repetition … without repetition: Testing the effect of instructed repetition on truth judgments

“…Although this null effect might be due to participants' lack of knowledge, prior studies have shown that the experience of fluency is still used as a valid cue for truth when knowledge about statements' content (Fazio et al, 2015;Fazio et al, 2019), source credibility (Begg et al, 1992;Unkelbach & Stahl, 2009), and declarative advice about the credibility of a statement (Unkelbach & Greifeneder, 2018) suggest the opposite. This is also illustrated in a recent study that found a truth effect for highly implausible statements, such as "earth is a perfect square", for which knowledge (of falsity) is present (Lacassagne et al, 2021).…”

Illusory Implications: Mere exposure to ideas can induce beliefs

“…The e ect has been demonstrated for frivolous trivia questions (e.g. Hasher et al, 1977;Lacassagne, Béna, & Corneille, 2021;Unkelbach, 2007;Wang, Brashier, Wing, Marsh, & Cabeza, 2016) as well as consequential fake news headlines (Pennycook et al, 2018). The illusory truth e ect has also been shown to be robust across people with di erent levels of cognitive ability, need for cognitive closure, and cognitive styles (De keersmaecker et al, 2020).…”