Repetition increases belief in climate-skeptical claims, even for climate science endorsers

RESEARCH ARTICLE Repetition increases belief in climate-skeptical claims, even for climate science endorsers Yangxueqing Jiang1, Norbert SchwarzID2,3,4*, Katherine J. Reynolds1,5, Eryn J. Newman1 1 School of Medicine and Psychology, The Australian National University, Canberra, ACT, Australia, 2 Mind and Society Center, University of Southern California, Los Angeles, California, United States of America, 3 Department of Psychology, University of Southern California, Los Angeles, California, United States of America, 4 Marshall School of Business, University of Southern California, Los Angeles, California, United States of America, 5 Melbourne Graduate School of Education, The University of Melbourne, Parkville, VIC, Australia * norbert.schwarz@usc.edu Abstract Does repeated exposure to climate-skeptic claims influence their acceptance as true, even among climate science endorsers? Research with general knowledge claims shows that repeated exposure to a claim increases its perceived truth when it is encountered again. However, motivated cognition research suggests that people primarily endorse what they already believe. Across two experiments, climate science endorsers were more likely to believe claims that were consistent with their prior beliefs, but repeated exposure increased perceptions of truth for climate-science and climate-skeptic claims to a similar extent. Even counter-attitudinal claims benefit from previous exposure, highlighting the insidious effect of repetition. Introduction

Misinformation travels via many means. False claims may originate on fringe websites, be widely shared on social media, and repeated by mainstream media, often with the aim to pro- vide “balanced reporting” that gives a voice to all sides. Unfortunately, the mere repetition of a claim can increase the degree to which people accept it as true [1, 2]. While this “illusory truth effect” (ITE) is well established, most of the evidence pertains to everyday knowledge and trivia. It remains unclear whether repetition also increases people’s assessments of truth when the content of repeated claims clashes with their own strongly held beliefs and attitudes. We address this question in a context that has received particular attention in discussions of “bal- anced reporting”, namely the repetition of claims that are incompatible with well-established insights of climate science [3–5]. Specifically, we test, (i) whether repetition increases the per- ceived truth of climate claims that are aligned with climate scientists vs. climate skeptics, (ii) whether the impact of claim repetition is moderated by recipients’ prior climate change beliefs, with a particular interest in (iii) whether repeating climate skeptic-aligned claims can increase their perceived truth even among recipients who are highly concerned about climate change. Whereas metacognitive theorizing suggests that repetition is likely to increase the perceived PLOS ONE PLOS ONE | https://doi.org/10.1371/journal.pone.0307294 August 7, 2024 1 / 19 a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 OPEN ACCESS

Citation: Jiang Y, Schwarz N, Reynolds KJ, Newman EJ (2024) Repetition increases belief in climate-skeptical claims, even for climate science endorsers. PLoS ONE 19(8): e0307294. https://doi. org/10.1371/journal.pone.0307294 Editor: Cengiz Erisen, Yeditepe University, TU¨ RKIYE Received: July 26, 2023 Accepted: July 2, 2024 Published: August 7, 2024 Copyright: © 2024 Jiang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are within the manuscript and its Supporting Information files. Funding: The author(s) received no specific funding for this work. Competing interests: The authors have declared that no competing interests exist.