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

Does Foreign-Accented Speech Affect Credibility? Evidence from the Illusory-Truth Paradigm

In a pioneering study, Lev-Ari and Keysar (2010) observed that unknown statements are judged less credible when uttered with foreign accent compared to native accent. This finding was interpreted in terms of processing fluency; when intelligibility is reduced, the credibility of the message decreases. Here, we use the illusory truth paradigm to explore how accent affects credibility. In a between-participant design, participants were exposed to unknown statements uttered by native-accented or foreign-accented speakers. After a distractor task, the same statements were presented with new statements, and participants assessed their truthfulness. Truthfulness ratings were higher for repeated statements than for new statements, replicating the illusory truth effect. Contrary to the processing fluency hypothesis, the effect was similar in both the foreign-accented and native-accented speech groups. A new group of participants rated the speakers' voices on various social traits. A negative bias against foreign speakers was observed. However, this negative-bias did not affect truth ratings.The impact of foreign-accented speech on message credibility is discussed in the context of two factors, processing fluency and out-group stereotype activation.

Who shows the Unlikelihood Effect - and why?

Recent work shows that people judge an outcome as less likely when they learn the probabilities of all single pathways that lead to that outcome, a phenomenon termed the Unlikelihood Effect. The initial explanation for this effect is that the low pathway probabilities trigger thoughts that deem the outcome unlikely. We tested the alternative explanation that the effect results from people's erroneous interpretation and processing of the probability information provided in the paradigm. By reanalyzing the original experiments, we discovered that the Unlikelihood Effect had been substantially driven by a small subset of people who give extremely low likelihood judgments. We conducted six preregistered experiments, showing that these people are unaware of the total outcome probability and do formally incorrect calculations with the given probabilities. Controlling for these factors statistically and experimentally reduced the proportion of people giving extremely low likelihood judgments, reducing and sometimes eliminating the Unlikelihood Effect. Our results confirm that the Unlikelihood Effect is overall a robust empirical phenomenon, but suggest that the effect results at least to some degree from a few people's difficulties with encoding, understanding, and integrating probabilities. Our findings align with current research on other psychological effects, showing that empirical effects can be caused by participants engaging in qualitatively different mental processes.

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.

Are There Reliable Qualitative Individual Difference in Cognition?

In this paper we propose a new set of questions that focus on the direction of effects. In almost all studies the direction is important. For example, in a Stroop task we expect responses to incongruent items to be slower than those to congruent ones, and this direction implies one theoretical explanation. Yet, if congruent words are slowed down relative to incongruent words we would have a completely different theoretical explanation. We ask a ‘does everybody’ question, such as, ‘does every individual show a Stroop effect in the same direction?’ Or, ‘does every individual respond faster to loud tones than soft tones?’ If all individuals truly have effects in the same direction that implicate a common theory, we term the differences among them as quantitative individual differences. Conversely, if all individuals truly have effects in different directions that implicate different theories, we term the differences among them as qualitative individual differences. Here, we provide a users guide to the question of whether individual differences are qualitative or quantitative. We discuss theoretical issues, methodological advances, new software for assessment, and, most importantly, how the question impacts theory development in cognitive science. Our hope is that this mode of analysis is a productive tool in researchers’ toolkits.

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.