The differential effects of fluency due to repetition and fluency due to color contrast on judgments of truth

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.

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.

Nomen est omen? How and when company name fluency affects return expectations

Investors perceive stocks of companies with fluent names as more profitable. This perception may result from two different channels: a direct, non-deliberate affect toward fluent names or a deliberate interpretation of fluent names as a signal for company quality. We use preregistered experiments to disentangle these channels and test their limitations. Our results indicate the existence of a significant non-deliberate fluency effect, while the deliberate fluency effect can be activated and deactivated in boundary cases. Both effects are consistent across different groups of participants. However, whereas the fluency effect is strong in isolation, it has limitations when investors are confronted with additional information about the stock.

The Role of Valence Matching in the Truth-by-Repetition Effect

People judge repeated information as truer than new information, a “truth-by-repetition” effect. Because repetition increases processing fluency, which is assumed to elicit positive affect, participants may match their positive experience associated with repeated information with a positive (“true”) rather than negative (“false”) response. We tested this valence-matching hypothesis in a preregistered experiment by manipulating the affective congruency of the response format. Specifically, in the congruent condition, participants had to select a positive (negative) picture to respond “true” (“false”). In the incongruent condition, we reversed these associations. In line with the valence matching hypothesis, the truth-by-repetition effect was larger in the congruent than incongruent condition. However, the effect was small, and Bayesian analyses were inconclusive. In addition, the truth-by-repetition effect was significant in both response format conditions. The results suggest a possible contribution of a valence matching process to the truth-by-repetition effect, but one that does not challenge extant models.

Is Earth a perfect square? Repetition increases the perceived truth of highly implausible statements

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 has found that statements contradicting participants' prior knowledge (as established from a first sample of participants) show a TBR effect following their repetition (in a second, independent sample of participants). As for now, however, attempts at finding a TBR effect for blatantly false (i.e., highly implausible) statements have failed. Here, we reasoned that highly implausible statements such as Elephants run faster than cheetahs may show repetition effects, provided a sensitive truth measure is used and statements are repeated more than just once. In a preregistered experiment, participants judged on a 100-point scale the truth of highly implausible statements that were either new to them or had been presented five times before judgment. We observed an effect of repetition: repeated statements were judged more true than new ones, although all judgments were judged below the scale midpoint. Exploratory analyses additionally show that about half the participants showed no or even a reversed effect of repetition. The results provide the first empirical evidence 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.

Bad after bad is good: previous trial disfluency reduces interference promoted by incongruence

Conflict and perceptual disfluency have been shown to lead to adaptive, sequential, control adjustments. Here, we propose that these effects can be additive, suggesting their integration into a general feeling of disfluent information processing. This hypothesis was tested using an interference task that dynamically mixed trials varying in legibility and/or congruence. Moreover, the manipulation of the proportion of congruent trials within the task allowed differentiating conditions in which these experiences of fluency may vary. Results showed that progressive increases in processing disfluency elicited a matching decrease in the interference of incongruent fluent trials. This linear effect was significant for all proportion of congruence conditions, although lower when incongruent trials were more frequent. These results highlight the role of feelings in the initiation of control and suggest that the monitoring system could be using changes in information processing fluency as a need-for-control signal.

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.

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.

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.

The Effect of Repetition on Truth Judgments Across Development

According to numerous research studies, when adults hear a statement twice, they are more likely to think it is true compared with when they have heard it only once. Multiple theoretical explanations exist for this illusory-truth effect. However, none of the current theories fully explains how or why people begin to use repetition as a cue for truth. In this preregistered study, we investigated those developmental origins in twenty-four 5-year-olds, twenty-four 10-year-olds, and 32 adults. If the link between repetition and truth is learned implicitly, then even 5-year-olds should show the effect. Alternatively, realizing this connection may require metacognition and intentional reflection, skills acquired later in development. Repetition increased truth judgments for all three age groups, and prior knowledge did not protect participants from the effects of repetition. These results suggest that the illusory-truth effect is a universal effect learned at a young age.

Easy on the mind, easy on the wrongdoer? No evidence for perceptual fluency effects on moral wrongness ratings

Processing fluency-the subjective ease of information processing-influences a variety of judgments (e.g., judgments of familiarity, liking, and truth). A study by Laham, Alter, and Goodwin (2009) suggests that this is also true for moral judgments. More specifically, the authors found that discrepant perceptual fluency mitigates moral wrongness ratings. In five studies (total N = 694), we tested the replicability of this finding for different kinds of scenarios (moral versus conventional transgressions) and different perceptual fluency manipulations. In Studies 1a and 1b we manipulated fluency by text background, in Studies 2a and 2b by font type, and in Study 3 by word spaces. Critically, none of the studies replicated Laham et al.'s discrepant fluency effect on moral wrongness ratings. In turn, we found that moral wrongness ratings were strongly affected by participants' emotional responses to the scenarios. Taken together, the findings of our five studies cast very strong doubt on perceptual fluency effects on moral judgments.

The in-out effect: examining the role of perceptual fluency in the preference for words with inward-wandering consonantal articulation

Words whose consonantal articulation spots wander inward, simulating ingestion movements, are preferred to words featuring the opposite consonantal articulation direction, that is, resembling expectoration movements. The underlying mechanism of this so-called in-out effect is far from settled. Contrary to the original explanation proposing an oral approach-avoidance mechanism, recent evidence has been used to support an oral motor-fluency mechanism, suggesting that inward words are preferred because they may be more common and/or easier to pronounce. Across six experiments (n = 1123), we examined the impact of different fluency sources in the emergence of the in-out effect. The preference for inward-wandering words persisted both with classical font type and figure-ground contrast fluency manipulations, and no systematic additive effects were observed. The in-out effect was also replicated for the first time with a between-participant design. These results suggest that the in-out effect may be permeable to fluency manipulations, but it is not dependent upon a plain fluency mechanism.

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.

Off the top of my head: Malleability and stability in natural categories

Previous research has found that category representations are highly malleable knowledge structures, varying widely across different contexts and individuals. However, it has also been found that such malleability does not apply equally to all types of category information. The present research further investigates the representational malleability versus stability of natural taxonomic categories. Using perceptual fluency as means to induce malleability, we explored whether malleability is moderated by the degree of typicality of category information. In the first experiment, we found that fluency-based malleability only occurs for non-typical category information. In follow-up experiments, we investigated the boundary conditions under which such fluency-based malleability occurs. Namely, in Experiment 2, we showed that the effect of fluency on non-typical features disappeared when there is a sensory modality mismatch between study and test phases. Finally, in Experiment 3, we demonstrated that this effect reappears in the modality mismatch condition when participants are given a response deadline. The implications of these findings to current theories of category representation and the perceptual fluency literature are discussed.

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.

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

We contrast the effects of conceptual and perceptual fluency resulting from repetition in the truth effect. In Experiment 1, participants judged either verbatim or paraphrased repetitions, which reduce perceptual similarity to original statements. Judgments were made either immediately after the first exposure to the statements or after one week. Illusions of truth emerged for both types of repetition, with delay reducing both effects. In Experiment 2, participants judged verbatim and paraphrased repetitions with either the same or a contradictory meaning of original statements. In immediate judgments, illusions of truth emerged for repetitions with the same meaning and illusions of falseness for contradictory repetitions. In the delayed session, the illusion of falseness disappeared for contradictory statements. Results are discussed in terms of the contributions of recollection of stimulus details and of perceptual and conceptual fluency to illusions of truth at different time intervals and judgmental context conditions.

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

Typically, people are more likely to consider a previously seen or heard statement as true compared to a novel statement. This repetition-based "truth effect" is thought to rely on fluency-truth attributions as the underlying cognitive mechanism. In two experiments, we tested the nature of the fluency-attribution mechanism by means of warning instructions, which informed participants about the truth effect and asked them to prevent it. In Experiment 1, we instructed warned participants to consider whether a statement had already been presented in the experiment to avoid the truth effect. However, warnings did not significantly reduce the truth effect. In Experiment 2, we introduced control questions and reminders to ensure that participants understood the warning instruction. This time, warning reduced, but did not eliminate the truth effect. Assuming that the truth effect relies on fluency-truth attributions, this finding suggests that warned participants could control their attributions but did not disregard fluency altogether when making truth judgments. Further, we found no evidence that participants overdiscount the influence of fluency on their truth judgments.