Unveiling the truth: warnings reduce the repetition-based truth effect

The illusory-truth effect and its absence under accuracy-focused processing are robust across contexts of low and high advertising exposure

In present-day digital environments, people frequently encounter content from sources of questionable trustworthiness. Advertising is an untrustworthy source because its purpose is to persuade consumers rather than to provide impartial information. One factor known to enhance the perceived truth of advertising claims is repetition: Repeated advertising claims receive higher truth ratings than novel advertising claims. The phenomenon that repetition enhances processing fluency which enhances truth judgments is known as the illusory-truth effect. Does repetition always enhance truth judgments? For instance, does repetition enhance truth judgments even in contexts with extensive advertising exposure in which enhanced processing fluency could be used to classify a statement as likely coming from an untrustworthy source? In two experiments, we examined the illusory-truth effect by presenting participants with product statements in an exposure phase and collecting truth judgments for both repeated and new statements in a test phase. In a low-advertising-exposure condition, most of the statements were labeled as scientific studies while in the high-advertising-exposure condition, most of the statements were labeled as advertising. When participants read the product statements in the exposure phase, a typical illusory-truth effect was obtained: In the test phase, repeated statements received higher truth ratings than new statements. However, when participants were instructed to adopt an accuracy focus at encoding by judging the truth of the product statements, new statements were judged to be as true as repeated statements. Both the illusory-truth effect and its absence under accuracy-focus instructions were found to be robust across different levels of advertising exposure.

The search for the missing link between health misinformation & health disparities

Relative to the rapid increase in available health information, little has been published on the differential impact misinformation has on the health of communities. Observations during the height of the COVID-19 pandemic indicated there were communities that made decisions that negatively impacted health outcomes beyond expectations; we propose that health misinformation was a contributor to poor health outcomes. Health misinformation exposure varies across communities and preliminary research suggests that some communities are more vulnerable to the impact of health misinformation than others. However, few studies have evaluated the connection between health misinformation and healthcare disparities. In this paper, we (a) review the current literature on misinformation and its impact on health disparities, (b) expand on prior epidemiological models to explain the communal spread of misinformation and the link to disparate health outcomes, (c) identify gaps in knowledge about communal misinformation spread (d) review promising interventions to halt the adverse impact of misinformation.

Why Do People Believe in Vaccine Misinformation? The Roles of Perceived Familiarity and Evidence Type

The proliferation of health misinformation poses a significant threat to public health, making it increasingly important to understand why misinformation is accepted. The illusory truth effect, which refers to the increased believability of a message due to repeated exposure, has been widely studied. However, there is limited research on this effect in the context of COVID-19 vaccine misinformation. This paper aims to examine the role of perceived familiarity with COVID-19 vaccine misinformation on various message perceptions, including perceived accuracy, agreement, perceived message effectiveness, and determinants of vaccination, including vaccine attitude and vaccination intention. Furthermore, it explores the impact of misinformation evidence (statistical vs. narrative) on the magnitude of the effects of perceived familiarity. To investigate these factors, a between-subjects experimental study was conducted, employing a 2 (Familiarity: strong vs. weak) × 3 (Evidence type: statistical, narrative, and both evidence) + 1 (Control: a message about drinking water) design. The results revealed that perceived familiarity with COVID-19 vaccine misinformation significantly predicted perceived accuracy, which was found to be negatively correlated with vaccine attitudes and vaccination intentions. Moreover, statistical evidence presented in misinformation was perceived as more persuasive in perceived message effectiveness, compared to narrative and mixed evidence. Interestingly, the effects of perceived familiarity were not contingent on the type of evidence used in COVID-19 vaccine misinformation. These findings emphasize the importance of avoiding the repetition of misinformation, reducing the processing fluency associated with misinformation correction, and educating individuals on how to critically evaluate statistical evidence when encountering (mis)information.

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

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.

More familiar, more credible? Distinguishing two types of familiarity on the truth effect using the drift-diffusion model

Familiar information is more likely to be accepted as true. This illusory truth effect has a tremendous negative impact on misinformation intervention. Previous studies focused on the familiarity from repeated exposure in the laboratory, ignoring preexisting familiarity with real-world misinformation. Over three studies (total N = 337), we investigated the cognitive mechanisms behind the truth biases from these two familiarity sources, and whether fact-checking can curb such biased truth perceptions. Studies 1 and 2 found robust truth effects induced by two sources of familiarity but with different cognitive processes. According to the cognitive process model, repetition-induced familiarity reduced decision prudence. Preexisting familiarity instead enhanced truth-congruent evidence accumulation. Study 3 showed that pre-exposing statements with warning flags eliminated the bias to truth induced by repetition but not that from preexisting familiarity. These repeated statements with warning labels also reduced decision caution. These findings furthered the understanding of how different sources of familiarity affect truth perceptions and undermine the intervention through different cognitive processes.

Illusions of knowledge due to mere repetition

Repeating information increases people's belief that the repeated information is true. This truth effect has been widely researched and is relevant for topics such as fake news and misinformation. Another effect of repetition, which is also relevant to those topics, has not been extensively studied so far: Do people believe they knew something before it was repeated? We used a standard truth effect paradigm in four pre-registered experiments (total N = 773), including a presentation and judgment phase. However, instead of "true"/"false" judgments, participants indicated whether they knew a given trivia statement before participating in the experiment. Across all experiments, participants judged repeated information as "known" more often than novel information. Participants even judged repeated false information to know it to be false. In addition, participants also generated sources of their knowledge. The inability to distinguish recent information from well-established knowledge in memory adds an explanation for the persistence and strength of repetition effects on truth. The truth effect might be so robust because people believe to know the repeatedly presented information as a matter of fact.

The illusory truth effect: A review of how repetition increases belief in misinformation

Repetition increases belief in information, a phenomenon known as the illusory truth effect. In laboratory experiments, the illusory truth effect has often been examined using general trivia statements as stimuli, but repetition also increases belief in misinformation, such as fake news headlines and conspiracy beliefs. Repetition even increases belief in claims that are implausible or that contradict prior knowledge. Repetition also has broader impacts beyond belief, such as increasing sharing intentions of news headlines and decreasing how unethical an act is perceived to be. Although the illusory truth effect is robust, some interventions reduce its magnitude, including instruction to focus on accuracy and awareness of the illusory truth effect. These strategies may be effective for reducing belief in misinformation.

An ongoing secondary task can reduce the illusory truth effect

Introduction

People are more likely to believe repeated information-this is known as the Illusory Truth Effect (ITE). Recent research on the ITE has shown that semantic processing of statements plays a key role. In our day to day experience, we are often multi-tasking which can impact our ongoing processing of information around us. In three experiments, we investigate how asking participants to engage in an ongoing secondary task in the ITE paradigm influences the magnitude of the effect of repetition on belief.

Methods

Using an adapted ITE paradigm, we embedded a secondary task into each trial of the encoding and/or test phase (e.g., having participants count the number of vowels in a target word of each trivia claim) and calculated the overall accuracy on the task.

Results

We found that the overall ITE was larger when participants had no ongoing secondary task during the experiment. Further, we predicted and found that higher accuracy on the secondary task was associated with a larger ITE.

Discussion

These findings provide initial evidence that engaging in an ongoing secondary task may reduce the impact of repetition. Our findings suggest that exploring the impact of secondary tasks on the ITE is a fruitful area for further research.

People underestimate the influence of repetition on truth judgments (and more so for themselves than for others)

People judge repeated statements as more truthful than new statements: a truth effect. In three pre-registered experiments (N = 463), we examined whether people expect repetition to influence truth judgments more for others than for themselves: a bias blind spot in the truth effect. In Experiments 1 and 2, using moderately plausible and implausible statements, respectively, the test for the bias blind spot did not pass the significance threshold set for a two-step sequential analysis. Experiment 3 considered moderately plausible statements but with a larger sample of participants. Additionally, it compared actual performance after a two-day delay with participants' predictions for themselves and others. This time, we found clear evidence for a bias blind spot in the truth effect. Experiment 3 also showed that participants underestimated the magnitude of the truth effect, especially so for themselves, and that predictions and actual truth effect scores were not significantly related. Finally, an integrative analysis focusing on a more conservative between-participant approach found clear frequentist and Bayesian evidence for a bias blind spot. Overall, the results indicate that people (1) hold beliefs about the effect of repetition on truth judgments, (2) believe that this effect is larger for others than for themselves, (3) and underestimate the effect's magnitude, and (4) particularly so for themselves.

Repetition could increase the perceived truth of conspiracy theories

Conspiracy theories can be encountered repeatedly, which raises the issue of the effect of their repeated exposure on beliefs. Earlier studies found that repetition increases truth judgments of factual statements, whether they are uncertain, highly implausible, or fake news, for instance. Would this "truth effect" be observed with conspiracy statements? If so, is the effect size smaller than the typical truth effect, and is it associated with individual differences such as cognitive style and conspiracy mentality? In the present preregistered study, we addressed these three issues. We asked participants to provide binary truth judgments to conspiracy and factual statements already displayed in an exposure phase (an interest judgment task) or that were new (displayed only in the truth judgment task). We measured participants' cognitive style with the three-item Cognitive Reflection Test (CRT), and conspiracy mentality with the Conspiracy Mentality Questionnaire (CMQ). Importantly, we found that repetition increased truth judgments of conspiracy theories, unmoderated by cognitive style and conspiracy mentality. Additionally, we found that the truth effect was smaller with conspiracy theories than with uncertain factual statements, and suggest explanations for this difference. The results suggest that repetition may be a simple way to increase belief in conspiracy theories. Whether repetition increases conspiracy beliefs in natural settings and how it contributes to conspiracism compared to other factors are important questions for future research.

The illusion of insight: detailed warnings reduce but do not prevent false "Aha!" moments

False "Aha!" moments can be elicited experimentally using the False Insight Anagram Task (FIAT), which combines semantic priming and visual similarity manipulations to lead participants into having "Aha!" moments for incorrect anagram solutions. In a preregistered experiment (N = 255), we tested whether warning participants and explaining to them exactly how they were being deceived, would reduce their susceptibility to false insights. We found that simple warnings did not reduce the incidence of false insights. On the other hand, participants who were given a detailed explanation of the methods used to deceive them experienced a small reduction in false insights compared to participants given no warning at all. Our findings suggest that the FIAT elicits a robust false insight effect that is hard to overcome, demonstrating the persuasive nature of false insights when the conditions are ripe for them.

The Effect of Repetition on the Perceived Truth of Tobacco-Related Health Misinformation Among U.S. Adults

As concerns about the effects of health misinformation rise, understanding why misbeliefs are accepted is increasingly important. People believe repeated statements more than novel statements, an effect known as truth by repetition, however this has not been examined in the context of tobacco information. Misbeliefs about tobacco are rampant and novel facts about tobacco are viewed as less believable. This paper examines how repetition of true and false tobacco statements affects truth perceptions. We recruited an online sample of 1,436 U.S. adults in May 2021. In an exposure phase, each participant rated their interest in 30 randomly selected statements about tobacco products and general knowledge trivia, half of them true and half false. The study had a two (tobacco product) by two (familiarity of statement claim) between-subjects design and a two (statement truth) by two (statement repetition) within-subjects design. During the testing phase participants rated the truthfulness of 24 repeated statements and 24 unseen statements. Repetition of true and false tobacco statements increased their subjective truth (diff=.20, p < .001), and the effect was larger for false claims compared to true claims. This underscores the importance of strategies to inoculate people against misinformation and calls for interventions that can stop the repetition of newly generated false claims.

What the Neuroscience and Psychology of Magic Reveal about Misinformation

When we believe misinformation, we have succumbed to an illusion: our perception or interpretation of the world does not match reality. We often trust misinformation for reasons that are unrelated to an objective, critical interpretation of the available data: Key facts go unnoticed or unreported. Overwhelming information prevents the formulation of alternative explanations. Statements become more believable every time they are repeated. Events are reframed or given "spin" to mislead audiences. In magic shows, illusionists apply similar techniques to convince spectators that false and even seemingly impossible events have happened. Yet, many magicians are "honest liars," asking audiences to suspend their disbelief only during the performance, for the sole purpose of entertainment. Magic misdirection has been studied in the lab for over a century. Psychological research has sought to understand magic from a scientific perspective and to apply the tools of magic to the understanding of cognitive and perceptual processes. More recently, neuroscientific investigations have also explored the relationship between magic illusions and their underlying brain mechanisms. We propose that the insights gained from such studies can be applied to understanding the prevalence and success of misinformation. Here, we review some of the common factors in how people experience magic during a performance and are subject to misinformation in their daily lives. Considering these factors will be important in reducing misinformation and encouraging critical thinking in society.

The effects of repeating false and misleading information on belief

False and misleading information is readily accessible in people's environments, oftentimes reaching people repeatedly. This repeated exposure can significantly affect people's beliefs about the world, as has been noted by scholars in political science, communication, and cognitive, developmental, and social psychology. In particular, repetition increases belief in false information, even when the misinformation contradicts prior knowledge. We review work across these disciplines, identifying factors that may heighten, diminish, or have no impact on these adverse effects of repetition on belief. Specifically, we organize our discussion around variations in what information is repeated, to whom the information is repeated, how people interact with this repetition, and how people's beliefs are measured. A key cross-disciplinary theme is that the most influential factor is how carefully or critically people process the false information. However, several open questions remain when comparing findings across different fields and approaches. We conclude by noting a need for more interdisciplinary work to help resolve these questions, as well as a need for more work in naturalistic settings so that we can better understand and combat the effects of repeated circulation of false and misleading information in society. This article is categorized under: Psychology > Memory Psychology > Reasoning and Decision Making.

The Trajectory of Truth: A Longitudinal Study of the Illusory Truth Effect

Repeated statements are rated as subjectively truer than comparable new statements, even though repetition alone provides no new, probative information (the illusory truth effect). Contrary to some theoretical predictions, the illusory truth effect seems to be similar in magnitude for repetitions occurring after minutes or weeks. This Registered Report describes a longitudinal investigation of the illusory truth effect (n = 608, n = 567 analysed) in which we systematically manipulated intersession interval (immediately, one day, one week, and one month) in order to test whether the illusory truth effect is immune to time. Both our hypotheses were supported: We observed an illusory truth effect at all four intervals (overall effect: χ 2(1) = 169.91; M repeated = 4.52, M new = 4.14; H1), with the effect diminishing as delay increased (H2). False information repeated over short timescales might have a greater effect on truth judgements than repetitions over longer timescales. Researchers should consider the implications of the choice of intersession interval when designing future illusory truth effect research.

An initial accuracy focus reduces the effect of prior exposure on perceived accuracy of news headlines

The illusory truth effect occurs when the repetition of a claim increases its perceived truth. Previous studies have demonstrated the illusory truth effect with true and false news headlines. The present study examined the effects that different ratings made during initial exposure have on the illusory truth effect with news headlines. In two experiments, participants (total N = 575) rated a set of news headlines in one of two conditions. Some participants rated how interesting they were, and others rated how truthful they were. Participants later rated the perceived accuracy of a larger set of headlines that included previously rated and new headlines. In both experiments, prior exposure increased perceived accuracy for participants who made initial interest ratings, but not for participants who made initial truthfulness ratings. The increase in perceived accuracy that accompanies repeated exposure was attenuated when participants considered the accuracy of the headlines at initial exposure. Experiment 2 also found evidence for a political bias: participants rated politically concordant headlines as more accurate than politically discordant headlines. The magnitude of this bias was related to performance on a cognitive reflection test; more analytic participants demonstrated greater political bias. These results highlight challenges that fake news presents and suggest that initially encoding headlines’ perceived truth can serve to combat the illusion that a familiar headline is a truthful one.

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.

The truth revisited: Bayesian analysis of individual differences in the truth effect

The repetition-induced truth effect refers to a phenomenon where people rate repeated statements as more likely true than novel statements. In this paper, we document qualitative individual differences in the effect. While the overwhelming majority of participants display the usual positive truth effect, a minority are the opposite-they reliably discount the validity of repeated statements, what we refer to as negative truth effect. We examine eight truth-effect data sets where individual-level data are curated. These sets are composed of 1105 individuals performing 38,904 judgments. Through Bayes factor model comparison, we show that reliable negative truth effects occur in five of the eight data sets. The negative truth effect is informative because it seems unreasonable that the mechanisms mediating the positive truth effect are the same that lead to a discounting of repeated statements' validity. Moreover, the presence of qualitative differences motivates a different type of analysis of individual differences based on ordinal (i.e., Which sign does the effect have?) rather than metric measures. To our knowledge, this paper reports the first such reliable qualitative differences in a cognitive task.

Truthiness, the illusory truth effect, and the role of need for cognition

Ease of processing-cognitive fluency-is a central input in assessments of truth, but little is known about individual differences in susceptibility to fluency-based biases in truth assessment. Focusing on two paradigms-truthiness and the illusory truth effect-we consider the role of Need for Cognition (NFC), an individual difference variable capturing one's preference for elaborative thought. Across five experiments, we replicated basic truthiness and illusory truth effects. We found very little evidence that NFC moderates truthiness. However, we found some evidence that (without an experimental warning), people high on NFC may be more susceptible to the illusory truth effect. This may reflect that elaborative thought increases the fluency with which encoded statements are processed after a delay (thus increasing the illusory truth effect). Future research may fruitfully test whether the influence of NFC and other individual difference measures depends on whether people are making immediate or delayed truth judgments.

Judging Truth

Deceptive claims surround us, embedded in fake news, advertisements, political propaganda, and rumors. How do people know what to believe? Truth judgments reflect inferences drawn from three types of information: base rates, feelings, and consistency with information retrieved from memory. First, people exhibit a bias to accept incoming information, because most claims in our environments are true. Second, people interpret feelings, like ease of processing, as evidence of truth. And third, people can (but do not always) consider whether assertions match facts and source information stored in memory. This three-part framework predicts specific illusions (e.g., truthiness, illusory truth), offers ways to correct stubborn misconceptions, and suggests the importance of converging cues in a post-truth world, where falsehoods travel further and faster than the truth.

Truth by Repetition: Explanations and Implications

People believe repeated information more than novel information; they show a repetition-induced truth effect. In a world of “alternative facts,” “fake news,” and strategic information management, understanding this effect is highly important. We first review explanations of the effect based on frequency, recognition, familiarity, and coherent references. On the basis of the latter explanation, we discuss the relations of these explanations. We then discuss implications of truth by repetition for the maintenance of false beliefs and ways to change potentially harmful false beliefs (e.g., “Vaccination causes autism”), illustrating that the truth-by-repetition phenomenon not only is of theoretical interest but also has immediate practical relevance.

Foreign language reduces the longevity of the repetition-based truth effect

Recent evidence suggests that judgment biases may diminish when a problem is presented in a foreign language. This foreign-language effect has primarily been examined with emotional materials such as risky-choice problems and moral dilemmas. In two experiments, we investigated the effect of foreign-language processing on an emotionally neutral judgment bias: the repetition-based truth effect, the phenomenon that statement repetition enhances the perceived truth of statements. In Experiment 1, we found no evidence for the truth effect to be moderated by the language in which the statements were processed (native language: Hungarian; foreign language: English). In Experiment 2, in turn, we not only manipulated language (native language: German; foreign language: English), but also the retention interval between statement repetitions. Replicating the findings of Experiment 1, language did not moderate the truth effect for statements that were repeated within the same experimental session. However, after a two-week interval, the truth effect was significantly smaller in the foreign-language condition than in the native-language condition. Overall, our findings suggest a faster decay of semantic memory for foreign-language as compared to native-language statements.