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, the researchers 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.
The study 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.
Interpreting the research
Misinformation poses danger to society. The alcohol industry is known to use misinformation to cause confusion about the actual harm caused by their products and spread doubt on scientific findings proving alcohol’s harms.
The Truth-by-Repetition (TBR) effect is one explanation for how people come to believe false information to be true. TBR effect says that repeating a statement increases how true it’s perceived to be. Processing fluency is a theory explaining the TBR effect. According to this theory, repetition makes the information easier to cognitively process, and this ease is misinterpreted as a signal that the information is true.
Until recently TBR was thought to apply only to statements that could conceivably be true. But new research is showing even implausible statements can seem more true due to the TBR effect.
Past studies have found that a single repetition of implausible statements such as “The Earth is a perfect square” did not influence the perceived truthfulness of the statement. The present researchers suggest that previous research methods may not have been sensitive enough to capture how the TBR effect worked on such implausible statements.
This study was conducted with 232 English-speaking, U.S.-based participants (51% female), recruited online. The researchers at UCLouvain in Belgium showed participants more false statement repetitions than in previous studies, and also had them respond on a scale with a substantially greater number of discrete ratings.
In phase 1 participants were presented with eight out of 16 statements rated as very implausible by participants from a previous study. Example statements include, highly implausible statements such as “Elephants weigh less than ants” and “Smoking is good for your lungs”, and implausible statements that might be considered true for U.S. participants such as “Rugby is the sport associated with Wimbledon.”
Participants rated how interesting the statements were and they were advised that the same statement might be shown several times. The statements were presented randomly and repeated five times each.
In phase 2, participants were randomly shown 16 statements, out of which they had previously seen eight statements repeatedly in phase 1. This time the participants were asked to rate how true each statement was on a scale from −50 (“definitely false”) to +50 (“definitely true”).
Key findings of the study
The study found that repeating implausible statements affected how truthful participants thought the statements were.
All ratings of truthfulness were in the negative range. But implausible statements that had been shown repeatedly were overall perceived to be less false than newly presented statements. Less extreme implausible statements were most affected by the TBR effect.
- 53% showed a positive TBR effect, with their ratings moving towards truth after statements were repeated,
- 19% showed no TBR effect.
- The remaining 28% showed a negative TBR effect, with repetition moving the ratings even more to the false side.
The findings of the study show that a surprisingly low number of repetitions can affect the perceived truth of highly implausible statements.
The changes in the perceived truthfulness of implausible statements were small after a few repetitions in this study. Repetitions over days and months could have more impact on the perceived truthfulness of misinformation. Investigating this can help to inform how the TBR effect works in the daily life of people.
For example, the alcohol industry has been spreading repeated misinformation on the health harms of their products for decades. Alcohol industry misinformation also falls into the category of less extreme implausible statements which are more susceptible to the TBR effect. The impact of such a long-term TBR effect could have very well convinced whole societies to believe falsehoods and disregard the harms of an addictive, cancer-causing product.
Research Digest: “Repetition can make even the most bizarre claims seem more true“