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Friday, May 8, 2020

Repetition increases Perceived Truth even for Known Falsehoods

Lisa Fazio
Originally posted 23 March 20

Repetition increases belief in false statements. This illusory truth effect occurs with many different types of statements (e.g., trivia facts, news headlines, advertisements), and even occurs when the false statement contradicts participants’ prior knowledge. However, existing studies of the effect of prior knowledge on the illusory truth effect share a common flaw; they measure participants’ knowledge after the experimental manipulation and thus conditionalize responses on posttreatment variables. In the current study, we measure prior knowledge prior to the experimental manipulation and thus provide a cleaner measurement of the causal effect of repetition on belief. We again find that prior knowledge does not protect against the illusory truth effect. Repeated false statements were given higher truth ratings than novel statements, even when they contradicted participants’ prior knowledge.

From the Discussion

As in previous research (Brashier et al., 2017; Fazio et al., 2015), prior knowledge did not protect participants from the illusory truth effect.Repeated falsehoods were rated as being more true than novel falsehoods, even when they both contradicted participants’ prior knowledge. By measuring prior knowledge before the experimental session, this study avoids conditioning on posttreatment variables and provides cleaner evidence for the effect (Montgomery et al., 2018). Whether prior knowledge is measured before or after the manipulation, it is clear that repetition increases belief in falsehoods that contradict existing knowledge.

The research is here.