The informative value of type of repetition: Perceptual and conceptual fluency influences on judgments of truth

Illusory truth effect across languages and scripts

The repetition of a statement increases its credibility, a phenomenon known as the illusory truth effect. Here we tested whether the illusory truth effect persists across languages and scripts. In two experiments, Italian-English (n = 80) and Greek-English (n = 66), unbalanced bilinguals were exposed to 60 written unknown trivia statements in English. After a distractor math task, participants rated the truthfulness of the same 60 (repeated) statements and 60 new statements, which were presented either in the same language as in the exposure phase (English) or in a different language (Italian, Experiment 1, or Greek, Experiment 2). Response times were faster when information was repeated in the same language compared to a different language, suggesting increased processing fluency in the former than in the latter case. Truth ratings yielded an illusory truth effect: repeated statements were considered more truthful than new statements. Interestingly, the magnitude of the illusory truth effect remained regardless of whether the repetition was in the same or in a different language and persisted even when the different language condition also entailed a different script (Latin in exposure phase and Greek in repetition). The results suggest that the language of information presentation is not a critical factor to affect the illusory truth effect, despite the fact that repetition in the same language increases processing speed. We interpret our results in light of the referential theory (Unkelbach & Rom, Cognition 160: 110-126, 2017), attributing the illusory truth effect to conceptual fluency induced by the overlap of activated conceptual representations in bilingual memory.

Repetition increases the perceived truth of inferred statements: evidence from transitive relations and non-transitive relations

The illusory truth effect refers to the phenomenon where repeated statements are more likely to be perceived as true compared to new statements. This effect encompasses not only verbatim repetition but also statements that are implied or inferred from the original. The illusory truth effect can be explained by the referential theory of truth, which posits that when processing a repeated statement, the previously formed coherent network will prompt individuals to judge it as true. Currently, the referential theory of truth still lacks evidence involving contexts with multiple statements. Our study investigates, across three experiments, whether statements inferred from multiple statements are perceived to be more true than new statements. Experiment 1a and 1b tested whether statements derived from transitive inference are judged more truthful. Experiment 2 used materials with non-transitive relations to see if erroneous inferred statements are also seen as more truthful. The results showed that, compared to new statements, statements inferred from the original statements with transitive relations are considered more truthful. More importantly, even when no transitive relations existed between the original statements, individuals still tend to perceive the erroneous inferred statements as more truthful compared to new statements. Our study provides new evidence for the referential theory of truth and highlights the role of inferential relations in establishing semantic network coherence. These findings further highlight the significant impact of the illusory truth effect in real-life situations.

Illusory implications: incidental exposure to ideas can induce beliefs

Numerous psychological findings have shown that incidental exposure to ideas makes those ideas seem more true, a finding commonly referred to as the 'illusory truth' effect. Under many accounts of the illusory truth effect, initial exposure to a statement provides a metacognitive feeling of 'fluency' or familiarity that, upon subsequent exposure, leads people to infer that the statement is more likely to be true. However, genuine beliefs do not only affect truth judgements about individual statements, they also imply other beliefs and drive decision-making. Here, we consider whether exposure to 'premise' statements affects people's truth ratings for novel 'implied' statements, a pattern of findings we call the 'illusory implication' effect. We argue these effects would constitute evidence for genuine belief change from incidental exposure and identify a handful of existing findings that offer preliminary support for this claim. Building upon these, we conduct three new preregistered experiments to further test this hypothesis, finding additional evidence that exposure to 'premise' statements affected participants' truth ratings for novel 'implied' statements, including for considerably more distant implications than those previously explored. Our findings suggest that the effects of incidental exposure reach further than previously thought, with potentially consequential implications for concerns around mis- and dis-information.

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.

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.

The illusory truth effect requires semantic coherence across repetitions

Repeated exposure to information increases its' perceived truth, and this illusory truth effect is often explained by two theoretical frameworks: the fluency account and the referential theory of truth. Whereas the fluency account suggests that prior activation of a single referent within a statement should increase its perceived truth, the referential theory makes no such predictions. The referential theory instead proposes that when a statement is processed, it activates the corresponding memory referents within that statement and strengthens the connection between these referents in the semantic memory network. Because repeated statements will have more coherent corresponding referents than new statements, they are perceived as relatively truer. Experiments 1 and 2 focused on testing the fluency account, with participants exposed to one or two of a statement's referents before evaluating that statement's truth. Experiments 3 and 4 focused on the referential theory by exposing participants to non-critical facts that linked together two of a critical statements' referents before evaluating the truth of the critical statements. We consistently observed a standard illusory truth effect, such that facts that repeated verbatim were rated as truer than new facts. However, perceived truth was not affected by prior exposure to the critical statement's topic (Experiment 1) or by prior exposure to non-critical facts related to the same topic(s) as the critical statement (Experiment 2). There was also no boost in perceived truth following prior exposure to non-critical facts that linked together two of the primary referents of the critical statement but did so in a semantically distinct manner from how those same referents were linked in the critical statement itself (Experiments 3 and 4). However, Experiment 4 demonstrated that perceived truth significantly increased if there was prior exposure to non-critical facts that linked two of the critical statement primary referents in a way that was semantically coherent with how those same referents were linked within the critical statement. Together, these results are consistent with the referential theory, and suggest that semantic consistency across repetitions plays a crucial role in leading to repetition-based illusory truth effects.

The evasive truth: do mere exposures at the subliminal and supraliminal levels drive the illusory truth effect?

The subjective truth of a statement is boosted by mere exposure to itself or a part of itself. This phenomenon is referred to as the illusory truth effect. We examined whether subliminal pre-exposure to the statement topic would increase its subjective truth. In the exposure phase, participants observed the topic, which was presented supraliminally or subliminally. After the exposure phase, they rated the subjective truth of the statement. If unconscious processing contributed to the illusory truth effect, subliminal exposure to the topic would increase the subjective truth of the statement. On the other hand, if the illusory truth effect required conscious and controlled processing, increases in the subjective truth of a statement would be induced only by supraliminal exposure to the topic. The results showed that the illusory truth effect was not found in either supraliminal or subliminal groups. Our findings provide no reliable evidence that pre-exposure to the statement topic saliently promotes its subjective truth.

The subjective feeling of a gap between conceptual and perceptual fluency is interpreted as a metacognitive signal of pastness

The present study aimed to address the following question: does the discrepancy between an expected word and its readability enhances or impair its memorability? We used an adaptation of the sentence stem paradigm (Whittlesea in J Exp Psycol 19:1235-1253, 1993) and manipulated the perceptual clarity of the words by introducing some Gaussian noise (Reber in Psycol Sci 9:45-48, 1998). The target words were semantically predictable or otherwise (conceptual fluency) or were easy or difficult to read (perceptual fluency). The first experiment was conducted to ensure that the two manipulated factors had an impact on the readability of the words. In particular, results showed that when the words were written against a noisy background their predictability enhanced the judgement of readability. The second experiment aimed to test the hypothesis that recognition would be influenced by the discrepancy between conceptual and perceptual fluency. The results showed that with a noisy background, the predictability of the target words had an impact on recognition judgement; with a clear background, the effect on the recognition judgement was caused by the non-predictability of the target words. Conversely, confidence in judgement increased when the two factors went in the same direction, that is, predictability with clarity and non-predictability with low clarity. The results showed that (a) depending on the task, the effects of conceptual and perceptual fluency did not go in the same direction; (b) the kinds of fluency (conceptual and perceptual) were not independent; and (c) recognition judgements were affected by the gap between conceptual and perceptual fluency.

Fluent processing leads to positive stimulus evaluations even when base rates suggest negative evaluations

Fluency is the experienced ease of ongoing mental operations, which increases the subjective positivity of stimuli attributes. This may happen because fluency is inherently positive. Alternatively, people may learn the meaning of fluency from contingencies within judgment-contexts. We test pseudocontingencies (PCs) as a mechanism through which fluency's meaning is learned. PCs are inferred correlations between two attributes due to the observation of their jointly skewed base rates - people relate what is frequent in one attribute to what is frequent in the other. Using online seller evaluations as the dependent variable, we manipulated base rates of seller name-fluency and seller reputation, creating conditions where name-fluency aligned positively or negatively with reputation. However, participants evaluated high-fluency name sellers more positively across base-rate conditions, although we observed negative PCs between seller reputation and a fluency-neutral dimension in a follow-up study. We discuss the implications for the debate regarding fluency's positive vs. malleable nature.

Judging fast and slow: The truth effect does not increase under time-pressure conditions

Due to the information overload in today’s digital age, people may sometimes feel pressured to process and judge information especially fast. In three experiments, we examined whether time pressure increases the repetition-based truth effect — the tendency to judge repeatedly encountered statements more likely as “true” than novel statements. Based on the Heuristic-Systematic Model, a dual-process model in the field of persuasion research, we expected that time pressure would boost the truth effect by increasing reliance on processing fluency as a presumably heuristic cue for truth, and by decreasing knowledge retrieval as a presumably slow and systematic process that determines truth judgments. However, contrary to our expectation, time pressure did not moderate the truth effect. Importantly, this was the case for difficult statements, for which most people lack prior knowledge, as well as for easy statements, for which most people hold relevant knowledge. Overall, the findings clearly speak against the conception of fast, fluency-based truth judgments versus slow, knowledge-based truth judgments. In contrast, the results are compatible with a referential theory of the truth effect that does not distinguish between different types of truth judgments. Instead, it assumes that truth judgments rely on the coherence of localized networks in people’s semantic memory, formed by both repetition and prior knowledge.

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.

More is easier? Testing the role of fluency in the more-credible effect

People are more likely to endorse statements of the form "A is more than B" than those of the form "B is less than A", even though the ordinal relationship being described is identical in both cases -– a result I dub the "more-credible" effect. This paper reports 9 experiments (total N = 5643) that probe the generality and basis for this effect. Studies 1–4 replicate the effect for comparative statements relating to environmental change and sustainable behaviours, finding that it is robust to changes in participant population, experimental design, response formats and data analysis strategy. However, it does not generalize to all stimulus sets. Studies 5–9 test the proposition that the effect is based on the greater ease of processing "more than" statements. I find no meaningful effect of warning people not to base their judgments on the fluency of the sentences (Studies 5 and 6), but do find associations between comparative language, credibility, and processing time: when the more-credible effect manifests, the more-than statements are read more quickly than the less-than statements, and this difference partly mediates the effect of comparative on agreement with the statements; in contrast, for a set of comparisons for which changes in the more/less framing did not affect truth judgments, there was no meaningful difference in the time taken to read the more- and less-than versions of the statements. Taken together, these results highlight the importance of comparative language in shaping the credibility of important socio-political messages, and provide some limited support for the idea that the effect of language choice is partly due to differences in how easily the statements can be processed -– although other mechanisms are also likely to be at work.

Perceived truth of statements and simulated social media postings: an experimental investigation of source credibility, repeated exposure, and presentation format

To better understand the spread of fake news in the Internet age, it is important to uncover the variables that influence the perceived truth of information. Although previous research identified several reliable predictors of truth judgments—such as source credibility, repeated information exposure, and presentation format—little is known about their simultaneous effects. In a series of four experiments, we investigated how the abovementioned factors jointly affect the perceived truth of statements (Experiments 1 and 2) and simulated social media postings (Experiments 3 and 4). Experiment 1 explored the role of source credibility (high vs. low vs. no source information) and presentation format (with vs. without a picture). In Experiments 2 and 3, we additionally manipulated repeated exposure (yes vs. no). Finally, Experiment 4 examined the role of source credibility (high vs. low) and type of repetition (congruent vs. incongruent vs. no repetition) in further detail. In sum, we found no effect of presentation format on truth judgments, but strong, additive effects of source credibility and repetition. Truth judgments were higher for information presented by credible sources than non-credible sources and information without sources. Moreover, congruent (i.e., verbatim) repetition increased perceived truth whereas semantically incongruent repetition decreased perceived truth, irrespectively of the source. Our findings show that people do not rely on a single judgment cue when evaluating a statement’s truth but take source credibility and their meta-cognitive feelings into account.

Relative to what? Dynamic updating of fluency standards and between-participants illusions of truth

Previous research has shown that fluency effects are driven by discrepancies between current and baseline fluency. Thus, illusions of truth associated with repetition (which increases statement fluency and its perceived truth-value relative to new statements) are less likely to occur when participants judge pure lists of either all-repeated or all-new statements and comparisons are between-participants, than when participants judge mixed lists and comparisons are within-participants. Still, there are demonstrations of between-participants illusions of truth in the literature. In this manuscript, we explain the emergence of between-participants truth effects in terms of hypothetical dynamic updating of fluency standards. The findings of two experiments provide evidence for this hypothesis by showing that between-participants truth effects occur most strongly for the first elements of the statement list but are reduced over time. The findings suggest that the dynamics of fluency experiences contribute to the truth effect and should be taken into account when investigating illusions of 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.

Make It Short and Easy: Username Complexity Determines Trustworthiness Above and Beyond Objective Reputation

Can the mere name of a seller determine his trustworthiness in the eye of the consumer? In 10 studies (total N = 608) we explored username complexity and trustworthiness of eBay seller profiles. Name complexity was manipulated through variations in username pronounceability and length. These dimensions had strong, independent effects on trustworthiness, with sellers with easy-to-pronounce or short usernames being rated as more trustworthy than sellers with difficult-to-pronounce or long usernames, respectively. Both effects were repeatedly found even when objective information about seller reputation was available. We hypothesized the effect of name complexity on trustworthiness to be based on the experience of high vs. low processing fluency, with little awareness of the underlying process. Supporting this, participants could not correct for the impact of username complexity when explicitly asked to do so. Three alternative explanations based on attributions of the variations in name complexity to seller origin (ingroup vs. outgroup), username generation method (seller personal choice vs. computer algorithm) and age of the eBay profiles (10 years vs. 1 year) were tested and ruled out. Finally, we show that manipulating the ease of reading product descriptions instead of the sellers' names also impacts the trust ascribed to the sellers.