PreprintPDF Available

Abstract and Figures

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 found a TBR effect with statements known to be false. Of note, a recent model even posits that repetition could increase the perceived truth of highly implausible statements. As for now, however, no empirical evidence has reported a TBR effect for highly implausible statements. Here, we reasoned that one may be found provided a sensitive truth measure is used and statements are repeated more than just once. In a preregistered experiment, participants judged the truth of highly implausible statements on a 100-point scale, and these statements were either new to them or had been presented five times before the judgment task. We observed a TBR effect: truth judgments were higher for repeated statements than for new ones-even if all statements were still judged as false. Exploratory analyses additionally suggest that all participants were not equally prone to this TBR effect: about half the participants showed no or even a reverse effect. Overall, the results provide direct empirical evidence to the claim 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.
Content may be subject to copyright.
TRUTH-BY-REPETITION EFFECT FOR HIGHLY IMPLAUSIBLE STATEMENTS 1
Is Earth a Perfect Square?
Repetition Increases the Perceived Truth of Highly Implausible Statements
Doris Lacassagne, Jérémy Béna & Olivier Corneille
UCLouvain, Belgium
[Preprint]
Word count: 2999 (without the title page, acknowledgments, references, footnotes, and figure
captions)
Running title: Truth-by-Repetition effect for highly implausible statements
Conflict of interest statement: The authors declare no conflict of interest.
Funding: This research did not receive any specific grant from funding agencies in the public,
commercial, or not-for-profit sectors.
Correspondence concerning this article should be addressed to Jérémy Béna, UCLouvain, PSP
IPSY, 10 Place du Cardinal Mercier, 1348, Louvain-la-Neuve, Belgium. Email:
jeremy.bena@uclouvain.be
CRediT authorship contribution statement
DL: Conceptualization, Formal analysis, Investigation, Methodology, Software, Writing
original draft. JB: Conceptualization, Data curation, Formal analysis, Investigation,
Methodology, Software, Visualization, Writing original draft, Writing review & editing. OC:
Conceptualization, Methodology, Supervision, Writing review & editing.
TRUTH-BY-REPETITION EFFECT FOR HIGHLY IMPLAUSIBLE STATEMENTS 2
Abstract
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 found a TBR
effect with statements known to be false. Of note, a recent model even posits that repetition could
increase the perceived truth of highly implausible statements. As for now, however, no empirical
evidence has reported a TBR effect for highly implausible statements. Here, we reasoned that one
may be found provided a sensitive truth measure is used and statements are repeated more than
just once. In a preregistered experiment, participants judged the truth of highly implausible
statements on a 100-point scale, and these statements were either new to them or had been
presented five times before the judgment task. We observed a TBR effect: truth judgments were
higher for repeated statements than for new ones - even if all statements were still judged as false.
Exploratory analyses additionally suggest that all participants were not equally prone to this TBR
effect: about half the participants showed no or even a reverse effect. Overall, the results provide
direct empirical evidence to the claim 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.
Keywords: truth effect; illusory truth; repetition; multiple exposures; low plausibility
TRUTH-BY-REPETITION EFFECT FOR HIGHLY IMPLAUSIBLE STATEMENTS 3
Is Earth a Perfect Square?
Repetition Increases the Perceived Truth of Highly Implausible Statements
1. Introduction
People are exposed every day to a large amount of information, some of which is false
(Marsh & Rajaram, 2019; Vosoughi et al., 2018), and sometimes seems highly implausible. In
general, repeated exposure to a given piece of information increases its believability. This Truth-
by-Repetition (TBR) effect is robust and has been demonstrated hundreds of times (for a meta-
analysis, see Dechêne et al., 2010; for early demonstrations, see Hasher et al., 1977; Bacon, 1979;
Schwartz, 1982; for a recent overview, see Unkelbach et al., 2019). A prominent theory is based
on processing fluency (Reber & Schwarz, 1999; Unkelbach, 2007): repeated statements are easier
to process than new ones, and this processing fluency is used as a cue for truth. Typically, the
TBR effect is demonstrated using only one previous exposure, but additional exposures (e.g., 4,
8, 16) may lead to a larger TBR effect (Arkes et al., 1991; DiFonzo et al., 2016; Fazio et al.,
2021; Hassan & Barber, 2021).
A critical question, from both a theoretical and practical standpoint, is whether the TBR
effect is observed for statements known to be false. A widespread assumption is that a
statement’s truth status must be ambiguous for a TBR effect to be found. In their meta-analysis of
the TBR effect, Dechêne et al. (2010, p.239) noted:
The only constraint seems to be that the statements have to be ambiguous, that is, participants
have to be uncertain about their truth status because otherwise the statements’ truthfulness will
be judged on the basis of their knowledge and not on the basis of fluency.”
TRUTH-BY-REPETITION EFFECT FOR HIGHLY IMPLAUSIBLE STATEMENTS 4
This “truth ambiguity” assumption has been formally implemented in Multinomial Processing
Tree (MPT) models. For instance, in Unkelbach and Stahl’s (2009) MPT model, a statement’s
factual truth is known with a probability k (for knowledge), and it is only in the absence of this
knowledge (1-k) that enhanced fluency should increase the probability f of judging this statement
as true (see also Hilbig, 2012, for a related model of truth judgments).
Recent studies finding a TBR effect with statements known to be false, however, question
the truth ambiguity assumption (Brashier et al., 2020; Fazio et al., 2015; Fazio et al., 2019;
Fazio, 2020). Fazio et al. (2015) compared the fit of two MPT models. One model was
knowledge-conditional; in that model, fluency drives judgments with a probability f only in the
absence of knowledge. The other model was fluency-conditional; in that model, fluency drives
judgments with a probability f, and knowledge drives judgments only in the absence of fluency.
In two experiments where some statements’ truth status was presumably known, these authors
found that the fluency-conditional model fitted the data well, while this was not the case for the
knowledge-conditional model. Further challenging the “truth ambiguity” assumption, Pennycook
et al. (2018) recently found a TBR effect with fake news, which commonly lacks plausibility
1
.
But how false and implausible can a statement be for resisting a TBR effect? Surprisingly
enough, very little research to date has informed this question of high theoretical and practical
relevance. Pennycook et al. (2018) did not find a TBR effect with extremely implausible
statements (e.g., The earth is a perfect square), which suggests a plausibility constraint on the
1
Relatedly, TBR effects were found even when declarative information about statements’ truth
status was available when performing truth judgments (Unkelbach & Greifeneder, 2018). The
truth ambiguity assumption is also questioned by studies finding TBR effects on statements
commonly known as true (Unkelbach & Speckmann, 2021).
TRUTH-BY-REPETITION EFFECT FOR HIGHLY IMPLAUSIBLE STATEMENTS 5
TBR effect. However, Fazio et al. (2019) proposed a model where repetition-induced belief is
constant across all levels of plausibility. In this model, repeated exposure to unambiguously false,
unambiguously true, and uncertain statements should lead to the same increase in belief in the
statements. Yet, because unambiguously false statements are unlikely to be judged as true
regardless of their repetition, the TBR effect is less likely to be observed with such statements.
Not categorizing as true a highly implausible statement, however, does not mean that
repetition did not influence its perceived truth value. It may just be the case that typical truth
measures are insufficiently sensitive to a repetition effect. A TBR effect may be observed when a
large gradient of falsehood is allowed. In the present study, we focused on highly implausible
statements and tested whether we could find empirical evidence for an effect of repetition on their
perceived truth. We choose to use only highly implausible statements because we believe finding
a TBR effect with such statements is of greatest concern from an applied perspective, as
misinformation and disinformation (e.g., fake news; hoaxes; conspiracy theories) can spread on a
large scale (e.g., Del Vicario et al., 2016; Vosoughi et al., 2018). In addition, a TBR effect on
highly plausible (but not highly implausible) statements could be constrained by ceiling effects.
Finding a TBR effect with highly implausible statements would suggest that even
blatantly false and preposterous information may benefit from repeated exposure. Here, we
departed from the typical TBR effect paradigm in two regards. First, repeated statements were
displayed five times (not only one) in the exposure phase. Second, we used a 100-point scale in
the truth judgment task (not a dichotomous rating task or a 7-point Likert scale). In doing so, we
may be able to detect a TBR effect for highly implausible statements, thereby giving credence to
Fazio et al.’s (2019) model and questioning the “truth ambiguity” assumption.
2. Method
TRUTH-BY-REPETITION EFFECT FOR HIGHLY IMPLAUSIBLE STATEMENTS 6
We report how we determined our sample size, all data exclusions, all manipulations, and
all measures in the study. The preregistration, experiment program, data, and analyses are
publicly available on https://osf.io/pe4g9/.
2.1 Participants and design
The design was a 2 (Repetition: New vs. Repeated five times) × 2 (Counterbalancing: Set
A repeated and Set B new vs. Set B repeated and Set A new), with the first factor within
participants.
We recruited 240 participants (our targeted sample size) on Prolific (51.25% female, one
not reported; Mage = 35.28; SDage = 11.96, one not reported). Participants (1) were English
speakers, (2) declared to live in the United States, (3) had an approval rate of at least 95%, and
(4) had already completed at least 100 previous submissions. Participants were paid US$1.41 for
completing the study. We excluded eight participants (seven participants did not end the study,
resulting in no data; one participant declared that they did not take their response seriously). This
resulted in a final sample size of 232 participants.
To determine sample size, we set α to .05, and we aimed for a statistical power of 80% to
detect an effect as small as Cohens d = 0.2 in a paired samples t-test. An analysis with G*Power
(Version 3.1.9.6, Faul et al., 2007) found that we would need 199 participants. To avoid a final
sample smaller than the targeted sample size, we have increased this estimate by 20%, resulting
in a targeted sample size of 240 participants.
2.2 Materials and procedure
We programmed the experiment with lab.js (Henninger et al., 2019), and we used JATOS
(Lange, Kühn, & Filevich, 2015) to run the study online on Prolific. We used the 16 most
TRUTH-BY-REPETITION EFFECT FOR HIGHLY IMPLAUSIBLE STATEMENTS 7
implausible statements used by Fazio et al. (2019) (only 0% to 20% of the participants rated them
as true).
Upon clicking on the study link, participants were told that we were interested in the role
of various variable in the evaluation of statements. After providing their informed consent,
participants entered the exposure phase. The instructions were as follow: In this first part, you
will judge how interesting some statements are to you on a scale from 1 (very uninteresting) to 6
(very interesting). For each statement, please select the value that most closely represents what
you think. Some of these statements will appear several times. When you are ready, please start
by pressing the spacebar. Participants rated their perceived interest on eight statements (either
from Set A or from Set B). The eight statements were presented five times in a random order,
resulting in 40 trials. To rate their interest, participants used a 6-point Likert scale (1: Very
uninteresting; 6: Very interesting) with no time limit. Upon clicking on their response, the next
statement was displayed with an intertrial blank screen of 500 milliseconds.
Right after the exposure phase, participants began the truth judgment task. The
instructions were as follow: In the following part, we are interested in how true you think some
statements are. Some statements will be repeated from the previous task. To evaluate the truth of
the statements, you will use a scale from -50 (Definitely false) to 50 (Definitely true). For each
statement, please select the value that most closely represents what you think. When you are
ready, please start by pressing the spacebar. Participants rated their perceived truth of 16
statements (half seen in the exposure phase) displayed in a random order on a scale from -50
(Definitely false) to +50 (Definitely true we recoded these values between 0 and 100), without
time limit.
TRUTH-BY-REPETITION EFFECT FOR HIGHLY IMPLAUSIBLE STATEMENTS 8
After the truth judgment task, we administered a seriousness check (based on Aust et al.,
2013) to exclude participants that did not take their responses seriously (participants were
informed that their response to this question would not affect their payment). We then thanked
and debriefed participants.
3. Results
3.1 Preregistered analyses
First, we conducted a Shapiro-Wilk test on differences between mean truth judgments on
repeated vs. new statements to determine whether we should use parametric or non-parametric
tests. Because data distribution was not normal, we used a Wilcoxon signed-rank test. However,
as the distribution was close to normal (see Figure 1B), we also report the frequentist and default
Bayesian preregistered paired samples t-tests.
Indicative of a TBR effect, participants judged repeated statements as more true (i.e., less
false) than new statements (see Figure 1; see Figure 2 for results by statements). This result is
apparent in both a Wilcoxon signed-rank test, Z = 4.65, p = 3.344e-06, rrb = .216, and a paired
samples t-test, t(231) = -4.49, p = 1.14e-5 , d = 0.278, 95%CId = [0.154; 0.402]. The default
Bayesian t-test yielded substantial evidence for the TBR effect, BF10 = 1023.89. Repeated (M =
8.79; SD = 9.22; Median = 6.25) and new (M = 6.43; SD = 7.48; Median = 3.31) statements were
all judged as false (as evidenced by ratings below 50, the mid-point of the scale) so repetition
TRUTH-BY-REPETITION EFFECT FOR HIGHLY IMPLAUSIBLE STATEMENTS 9
did not per se increase true judgments (as no statements were rated as true), but made
statements judged as slightly less false than new ones
2
.
3.2 Not preregistered analyses looking at subsets of participants.
We computed a TBR effect score for each participant (the difference between truth
judgment scores on repeated and new statements). In doing so, we were able to identify which
participants descriptively showed larger truth judgment scores on repeated vs. new statements
(positive scores), larger truth judgment scores on new vs. repeated statements (negative scores),
and no difference between repetition conditions (null scores). The results computed on the total
sample are driven by a subset of participants as only 52.58% (n = 122) had a positive TBR effect
score (M = 7.6, SD = 6.36), 19.4% (n = 45) had a null truth effect score, and interestingly 28.02%
(n = 65) had a negative TBR effect score (M = -5.82; SD = 5.67), the latter of which is
significantly different from 0, t(64) = -8.28, p = 1.05e-11, d = 1.027. Consistent with recent
findings (see below), these complementary analyses suggest that all participants are not equally
prone to the TBR effect.
2
In a non-preregistered 2 (Repetition: New; Repeated five times within-participants) × 2
(Counterbalancing: Set A repeated and Set B new vs. Set B repeated and Set A new between
participants) mixed ANOVA, we did not find a significant main (F(1, 230) = 0.01, p = .927 , η²G
< .001) or interactive (F(1, 230) = 0.64, p = .425 , η²G < .001) effect of the Counterbalancing
condition.
TRUTH-BY-REPETITION EFFECT FOR HIGHLY IMPLAUSIBLE STATEMENTS 10
Figure 1. Truth judgments as a function of Repetition (dashed horizonal line: no bias toward the
"False" or the “True” side) (A) and TBR effect scores (dashed horizontal line: no difference
between truth judgments scores on repeated and new statements; positive scores: higher truth
judgments for repeated than new statements; negative scores: higher truth judgments for new
than repeated statements) (B). The dots are the participants' scores (jittered). The lower and
upper limits of the boxplots are the 95% confidence intervals, with the mean in between. The
distributions represent the kernel probability density of the data.
TRUTH-BY-REPETITION EFFECT FOR HIGHLY IMPLAUSIBLE STATEMENTS 11
Figure 2. Mean truth judgments as a function of Statements and Repetition. The error bars are the 95% confidence intervals. The
statements were abbreviated for the sake of readability; the complete statements are available at https://osf.io/pe4g9/ .
TRUTH-BY-REPETITION EFFECT FOR HIGHLY IMPLAUSIBLE STATEMENTS 12
4. Discussion
Using five repetitions and a 100-point judgment scale allowing for finer-grained gradients
in perceived falsehood, we found a TBR effect on highly implausible statements: participants
started giving credence to statements as highly implausible as “Earth is a perfect square” or
Benjamin Franklin lived 150 years after repeating them for just five times. Beyond its practical
significance, this finding informs current models of the TBR effect. Contrary to the “truth
ambiguity” assumption endorsed in knowledge-conditional multinomial processing tree models.
Fazio et al.’s (2019) model posits that repetition increases the perceived truth of
statements at all gradients of plausibility. Although Fazio et al. found results consistent with this
model, their empirical evidence was only indirect. These authors reported an inverted U-shaped
relation between the size of the truth effect and the statements’ level of plausibility. However,
they did not find a TBR effect at the extremes of the distribution (i.e., with either highly
implausible or highly plausible statements; see Table 1 in Fazio et al., 2019).
Because we used five repetitions and a 100-point scale, our study simultaneously deviates
in two ways from usual TBR procedures where one repetition is implemented, and dichotomous
ratings/Likert scales are typically used. Therefore, we cannot say which feature (or a combination
thereof) is responsible for the current findings. There are reasons to think that increasing the
number of repetitions from one to five increased the likelihood to find a TBR effect, as suggested
by research on ambiguous statements (e.g., Fazio et al., 2021; Hassan & Barber, 2021). Likewise,
using a sensitive scale increased the probability of detecting small differences of perceived truth
between repeated and new statements that may be difficult to find with less sensitive
dichotomous ratings or Likert scales. Future research could orthogonally vary the number of
TRUTH-BY-REPETITION EFFECT FOR HIGHLY IMPLAUSIBLE STATEMENTS 13
repetitions and the truth judgment scale to quantify whether and how much each feature
contributes to the TBR effect with implausible statements.
Future research may also clarify the reason for interindividual variations in the TBR
effect. Almost half of the participants had a null TBR score or even showed lower perceived truth
on repeated than new statements. The variability between participants in the TBR effect was
greater here than the one estimated by Schnuerch et al. (2020) using Bayesian analyses. In their
study, about 20% of the participants did not demonstrate the typical TBR effect (see also
Henderson et al., 2021, who found that 14.8% of their sample did not show a TBR effect). We
can speculate on two non-exclusive explanations: the link between fluency and truth judgments
and demand characteristics.
First, processing fluency may not always be interpreted as a cue for truth. The way in
which fluency is interpreted can be reversed (Unkelbach, 2007; see also Silva et al., 2016).
Particularly relevant here is a recent study by Corneille et al. (2020) showing that in judgment
ecologies where misinformation is widespread (i.e., social media), a fakeness-by-repetition effect
is found, whereby perception of fakeness increases after a statement repetition. Because only
highly implausible statements were used in the present experiment, it may be that some
participants relied on fluency as a proxy for falsehood.
Second, participants can act in ways that confirm or refute an experimenters hypothesis
(Orne, 1962; for an integrative model, see Corneille & Lush, 2021): if participants identified that
we expected repeated statements to be judged as more true than new ones, they were able to
respond in line or against the hypothesis, accounting for individual differences in the observed
TBR effect. This could have been facilitated in our procedure, as recognition memory was likely
to be high (five repetitions: truth judgment task right after the exposure phase). This issue is
TRUTH-BY-REPETITION EFFECT FOR HIGHLY IMPLAUSIBLE STATEMENTS 14
alleviated, however, by the fact that we asked participants to judge their interest in statements in
the exposure phase: participants may have mistakenly believed that we were interested in the link
between perceived interest and perceived truth. Future research could assess whether the TBR
effect with implausible statements depends on hypothesis awareness, which could account for
individual differences in the demonstrated effect.
5. Conclusion
We found that even a very limited number of repetitions can increase the perceived truth
of highly implausible statements. Complementary analyses reveal that this is not equally true for
everyone, though: some individuals may be left unaffected by repetition and some others may
even show decreased perceived truth following repetition. Better understanding when, whom, and
why one may develop a sense of truth for implausible statements following their repetition is of
both high theoretical and practical interest.
TRUTH-BY-REPETITION EFFECT FOR HIGHLY IMPLAUSIBLE STATEMENTS 15
Acknowledgments
We thank Douglas Bancu, Olivier Desmedt, Antoine Mauclet, and Prof. Christian Unkelbach for
their valuable comments during the preparation of the manuscript.
References
Arkes, H. R., Boehm, L. E., & Xu, G. (1991). Determinants of judged validity. Journal of
Experimental Social Psychology, 27(6), 576605. https://doi.org/10.1016/0022-
1031(91)90026-3
Aust, F., Diedenhofen, B., Ullrich, S., & Musch, J. (2013). Seriousness checks are useful to
improve data validity in online research. Behavior Research Methods, 45(2), 527535.
https://doi.org/10.3758/s13428-012-0265-2
Bacon, F. T. (1979). Credibility of repeated statements: Memory for trivia. Journal of
Experimental Psychology: Human Learning and Memory, 5(3), 241252.
https://doi.org/10.1037/0278-7393.5.3.241
Brashier, N. M., Eliseev, E. D., & Marsh, E. J. (2020). An initial accuracy focus prevents illusory
truth. Cognition, 194, 104054. https://10.1016/j.cognition.2019.104054
Corneille, O., & Lush, P. (2021). Sixty years after Orne’s American Psychologist article: A
conceptual analysis of “Demand Characteristics”. https://doi.org/10.31234/osf.io/jqyvx
Corneille, O., Mierop, A., & Unkelbach, C. (2020). Repetition increases both the perceived truth
and fakeness of information: An ecological account. Cognition, 205, 104470.
https://doi.org/10.1016/j.cognition.2020.104470
TRUTH-BY-REPETITION EFFECT FOR HIGHLY IMPLAUSIBLE STATEMENTS 16
Dechêne, A., Stahl, C., Hansen, J., & Wänke, M. (2010). The Truth About the Truth: A Meta-
Analytic Review of the Truth Effect. Personality and Social Psychology Review, 14(2),
238257. https://doi.org/10.1177/1088868309352251
Del Vicario, M., Bessi, A., Zollo, F., Petroni, F., Scala, A., Caldarelli, G., … Quattrociocchi, W.
(2016). The spreading of misinformation online. Proceedings of the National Academy
of Sciences, 113(3), 554559. https://10.1073/pnas.1517441113
Difonzo, N., Beckstead, J., Stupak, N., & Walders, K. (2016). Validity judgments of rumors
heard multiple times: The shape of the truth effect. Social Influence, 11, 118.
https://doi.org/10.1080/15534510.2015.1137224
Faul, F., Erdfelder, E., Lang, A.-G., & Buchner, A. (2007). G*Power 3: A flexible statistical
power analysis program for the social, behavioral, and biomedical sciences. Behavior
Research Methods, 39(2), 175191. https://doi.org/10.3758/BF03193146
Fazio, L. K. (2020). Repetition Increases Perceived Truth Even for Known Falsehoods. Collabra:
Psychology, 6(38). https://doi.org/10.1525/collabra.347
Fazio, L., Pillai, R., & Patel, D. (2021). The effects of repetition on belief in naturalistic settings.
https://doi.org/10.31234/osf.io/r85mw
Fazio, L. K., Brashier, N. M., Payne, B. K., & Marsh, E. J. (2015). Knowledge does not protect
against illusory truth. Journal of Experimental Psychology: General, 144(5), 9931002.
https://doi.org/10.1037/xge0000098
Fazio, L. K., Rand, D. G., & Pennycook, G. (2019). Repetition increases perceived truth equally
for plausible and implausible statements. Psychonomic Bulletin & Review, 26(5),
17051710. https://doi.org/10.3758/s13423-019-01651-4
TRUTH-BY-REPETITION EFFECT FOR HIGHLY IMPLAUSIBLE STATEMENTS 17
Fazio, L., Pillai, R., & Patel, D. (2021). The effects of repetition on belief in naturalistic settings.
PsyArXiv. https://doi.org/10.31234/osf.io/r85mw
Hasher, L., Goldstein, D., & Toppino, T. (1977). Frequency and the Conference of Referential
Validity. Journal of Verbal Learning and Verbal Behavior, 16(1), 107-112.
Hassan, A., & Barber, S. J. (2021). The effects of repetition frequency on the illusory truth effect.
Cognitive Research: Principles and Implications, 6. https://doi.org/10.1186/s41235-021-
00301-5
Henderson, E. L., Simons, D. J., & Barr, D. J. (2021). The trajectory of truth: A longitudinal
study of the illusory truth effect. Journal of cognition, 4(1), 1-23.
https://doi.org/10.5334/joc.161
Henninger, F., Shevchenko, Y., Mertens, U., Kieslich, P. J., & Hilbig, B. E. (2019). lab.js: A free,
open, online study builder. PsyArXiv. https://doi.org/10.31234/osf.io/fqr49
Hilbig, B. E. (2012). How framing statistical statements affects subjective veracity: Validation
and application of a multinomial model for judgments of truth. Cognition, 125, 37-48.
https://doi.org/10.1016/j.cognition.2012.06.009
Lange, K., Kühn, S., & Filevich, E. (2015). Correction: “Just Another Tool for Online Studies”
(JATOS): An Easy Solution for Setup and Management of Web Servers Supporting
Online Studies. PLOS ONE, 10(7), e0134073.
https://doi.org/10.1371/journal.pone.0134073
Marsh, E. J., & Rajaram, S. (2019). The Digital Expansion of the Mind: Implications of Internet
Usage for Memory and Cognition. Journal of Applied Research in Memory and
Cognition, 8(1), 114. https://doi.org/10.1016/j.jarmac.2018.11.001
TRUTH-BY-REPETITION EFFECT FOR HIGHLY IMPLAUSIBLE STATEMENTS 18
Orne, M. T. (1962). On the social psychology of the psychological experiment: With particular
reference to demand characteristics and their implications. American Psychologist,
17(11), 776783. https://10.1037/h0043424
Pennycook, G., Cannon, T. D., & Rand, D. G. (2018). Prior exposure increases perceived
accuracy of fake news. Journal of Experimental Psychology: General, 147(12), 1865
1880. https://10.1037/xge0000465
Reber, R., & Schwarz, N. (1999). Effects of Perceptual Fluency on Judgments of Truth.
Consciousness and Cognition, 8(3), 338342. https://doi.org/10.1006/ccog.1999.0386
Schnuerch, M., Nadarevic, L., & Rouder, J. N. (2020). The truth revisited: Bayesian analysis of
individual differences in the truth effect. Psychonomic Bulletin & Review. Advance
online publication. https://doi.org/10.3758/s13423-020-01814-8
Schwartz, M. (1982). Repetition and rated truth value of statements. American Journal of
Psychology, 95(3), 393-407. https://doi.org/10.2307/1422132
Silva, R. R., Garcia-marques, T., & Mello, J. (2016). The differential effects of fluency due to
repetition and fluency due to color contrast on judgments of truth. Psychological
Research, 80(5), 821837. https://doi.org/10.1007/s00426-015-0692-7
Unkelbach, C. (2007). Reversing the Truth Effect: Learning the Interpretation of Processing
Fluency in Judgments of Truth. Journal of Experimental Psychology. Learning,
Memory, and Cognition, 33(1), 219230. https://doi.org/10.1037/0278-7393.33.1.219
Unkelbach, C., & Greifeneder, R. (2018). Experiential fluency and declarative advice jointly
inform judgments of truth. Journal of Experimental Social Psychology, 79, 7886.
https://doi.org/10.1016/j.jesp.2018.06.010
TRUTH-BY-REPETITION EFFECT FOR HIGHLY IMPLAUSIBLE STATEMENTS 19
Unkelbach, C., Koch, A., Silva, R. R., & Garcia-Marques, T. (2019). Truth by Repetition:
Explanations and Implications. Current Directions in Psychological Science, 28(3),
247253. https://doi.org/10.1177/0963721419827854
Unkelbach, C., & Speckmann, F. (2021). Mere repetition increases belief in factually true
COVID-19 related information. Journal of Applied Research in Memory and Cognition,
Advance online publication. https://doi.org/ 10.1016/j.jarmac.2021.02.001
Unkelbach, C., & Stahl, C. (2009). A multinomial modeling approach to dissociate different
components of the truth effect. Consciousness and Cognition, 18(1), 2238.
https://doi.org/10.1016/j.concog.2008.09.006
Vosoughi, S., Roy, D., & Aral, S. (2018). The spread of true and false news online. Science,
359(6380), 11461151. https://doi.org/10.1126/science.aap9559
ResearchGate has not been able to resolve any citations for this publication.
Article
Full-text available
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.
Article
Full-text available
Repeated information is often perceived as more truthful than new information. This finding is known as the illusory truth effect, and it is typically thought to occur because repetition increases processing fluency. Because fluency and truth are frequently correlated in the real world, people learn to use processing fluency as a marker for truthfulness. Although the illusory truth effect is a robust phenomenon, almost all studies examining it have used three or fewer repetitions. To address this limitation, we conducted two experiments using a larger number of repetitions. In Experiment 1, we showed participants trivia statements up to 9 times and in Experiment 2 statements were shown up to 27 times. Later, participants rated the truthfulness of the previously seen statements and of new statements. In both experiments, we found that perceived truthfulness increased as the number of repetitions increased. However, these truth rating increases were logarithmic in shape. The largest increase in perceived truth came from encountering a statement for the second time, and beyond this were incrementally smaller increases in perceived truth for each additional repetition. These findings add to our theoretical understanding of the illusory truth effect and have applications for advertising, politics, and the propagation of “fake news.”
Article
Full-text available
General Audience Summary The “truth effect” is the phenomenon that mere repetition increases belief in the repeated information, both relative to its initial presentation and relative to other, non-repeated information. This truth effect is currently recruited to explain how people come to believe apparently false information, which is a prominent topic in an age of “alternative facts” and “fake news.” We investigated if mere repetition may also increase beliefs in factually true and actually relevant information, namely information related to the ongoing COVID-19 pandemic. Such an increase would suggest a positive implication of the truth effect. Two experiments showed that overall, mere repetition indeed increased participants’ belief in true information related to the ongoing pandemic. However, this increase was significantly larger for less-known information; for well-known information, the increases were small. This suggests an asymmetry for the truth effect in the real world: as false information is more likely to be unknown or less known to people (e.g., novel conspiracy theories or novel false claims) compared to true information, the truth effect benefits false information more than true information. Nevertheless, overall, merely repeating information increased participants’ belief in the repeated information. Repetition thus may serve as a tool to increase belief in relevant true information related to the ongoing pandemic.
Article
Full-text available
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.
Article
Full-text available
General Audience Summary The internet is rapidly changing what information is available to us as well as how we find that information and share it with others. Here we ask how this “digital expansion of the mind” may change cognition. We begin by identifying ten properties of the internet that we know influence cognition, based on decades of cognitive science research as well as work examining other ways that people externalize memory and cognition (such as relying on other people to help one remember information or printing out information rather than trying to remember it). These properties can be roughly organized around (a) internet content (e.g., the sheer amount of information available, its relative accuracy, the frequency with which it changes, and the number of options offered at any one point in time); (b) internet usage (e.g., access is easy, equires searching, and returns results almost instantaneously); and (c) the community involved in the creation and propagation of content (e.g., anyone can participate, although authorship may often be obscured; perhaps most importantly, the internet connects people in an unprecedented fashion). We then identify questions arising from the combination of these properties; for example, we ask whether internet usage can become habitual, given its ease of access, the scope of information available, and the speed with which results are returned. In this fashion, we consider whether the internet encourages superficial processing of information, is a powerful source of misinformation, inflates people’s beliefs about what they believe they know, and changes how people remember their personal lives, among other questions. In so doing, we aim to redirect the field from questions about the internet as a place to store information to a broader consideration of how internet usage may affect many aspects of cognition, as people increasingly rely on the internet to seek, post, and share information.
Preprint
Full-text available
Web-based data collection is increasingly popular in both experimental and survey-based research, because it is flexible, efficient and location-independent. While dedicated software for laboratory-based experimentation and online surveys is commonplace, researchers looking to implement experiments in the browser have, heretofore, often had to manually construct their studies’ content and logic using code. We introduce lab.js, a free, open-source experiment builder that makes it easy to build experiments for both online and in-laboratory data collection. Through its visual interface, stimuli can be designed and combined into a study without programming, though studies’ appearance and behavior can be fully customized using HTML, CSS and JavaScript code if required. Presentation and response times are kept and measured with high accuracy and precision heretofore unmatched in browser-based studies. Experiments constructed with lab.js can be run directly on a local computer, and published online with ease, with direct deployment to cloud hosting, export to any web server, and integration with popular data collection tools. Studies can also be shared in an editable format, archived, re-used and adapted, enabling effortless, transparent replications, and thus facilitating open, cumulative science. The software is provided free of charge under an open-source license; further information, code and extensive documentation are available from https://lab.js.org/.
Article
Full-text available
The 2016 U.S. presidential election brought considerable attention to the phenomenon of “fake news”: entirely fabricated and often partisan content that is presented as factual. Here we demonstrate one mechanism that contributes to the believability of fake news: fluency via prior exposure. Using actual fake-news headlines presented as they were seen on Facebook, we show that even a single exposure increases subsequent perceptions of accuracy, both within the same session and after a week. Moreover, this “illusory truth effect” for fake-news headlines occurs despite a low level of overall believability and even when the stories are labeled as contested by fact checkers or are inconsistent with the reader’s political ideology. These results suggest that social media platforms help to incubate belief in blatantly false news stories and that tagging such stories as disputed is not an effective solution to this problem. It is interesting, however, that we also found that prior exposure does not impact entirely implausible statements (e.g., “The earth is a perfect square”). These observations indicate that although extreme implausibility is a boundary condition of the illusory truth effect, only a small degree of potential plausibility is sufficient for repetition to increase perceived accuracy. As a consequence, the scope and impact of repetition on beliefs is greater than has been previously assumed.
Preprint
In our modern well-connected world, false information spreads quickly and is often repeated multiple times. From laboratory studies, we know that this repetition can be dangerous as repetition increases belief. However, it is unclear how repetition affects belief in real-world settings. Here we examine a larger number of repetitions (16), more realistic timing of the repetitions (across two weeks), and more naturalistic exposures (text messages). 435 participants recruited from mTurk were texted true and false trivia statements across 15 days before rating the accuracy of each statement. Statements were seen either 1, 2, 4, 8, or 16 times. We find clear evidence that repetition increases belief. Initial repetitions produced the largest increase in perceived truth, but belief continued to increase with additional repetitions. The results imply that repeated exposure to false information can be dangerous and that technology companies and policymakers should do more to prevent the spread of misinformation.
Article
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.
Article
Processing fluency, the experienced ease of ongoing mental operations, influences judgments such as frequency, monetary value, or truth. Most experiments keep to-be-judged stimuli ambiguous with regards to these judgment dimensions. In real life, however, people usually have declarative information about these stimuli beyond the experiential processing information. Here, we address how experiential fluency information may inform truth judgments in the presence of declarative advice information. Four experiments show that fluency influences judged truth even when advice about the statements' truth is continuously available and labelled as highly valid; the influence follows a linear cue integration pattern for two orthogonal cues (i.e., experiential and declarative information). These data underline the importance of processing fluency as an explanatory construct in real-life judgements and support a cue integration framework to understand fluency effects in judgment and decision making.