Research & Insights

Repetition Makes Us Believe Misinformation

A study from Vanderbilt University, Duke University and the University of North Carolina bears out the old adage that if you repeat a lie often enough, it becomes the truth. At least, we’re more likely to believe it is true.

The study, designed by psychologist Lisa K. Fazio and her colleagues, involved 80 undergraduates at Duke University and was published in the October issue of the Journal of Experimental Psychology: General.

The researchers first compiled a list of general knowledge statements. Some of these statements were true (“A date is a dried plum”), while others were false (“The Atlantic Ocean is the largest ocean on Earth”). Half of the statements were likely to be known by most people (“The Cyclops is the legendary one-eye giant in Greek mythology”), while the other half was less likely to be known (Billy the Kid’s last name is Bonney”).

The study participants were first asked to evaluate how interesting they found each individual statement. Then, they were asked to rank the statements, along with some they had never seen before, in terms of their truth or falseness. Importantly, the participants saw some statements twice – once during the evaluation phase and once during the truthfulness phase.

The researchers found that “repetition increased perceived truthfulness, even for contradictions of well-known facts.” Prior studies have assumed that repetition only makes people more likely to believe statements that people are uncertain about, but these results suggest that we are likely to believe repeated falsehoods even when we know the truth.

“Repetition makes statements easier to process…relative to new statements, leading people to the (sometimes) false conclusion that they are more truthful,” the researchers explain. And although we are likely to actively evaluate the trustworthiness of information we’ve only recently learned, we’re less likely to do this when recalling information already stored in our brains. This means that an often-repeated statement will receive less scrutiny than something we recently learned.

Journal of Experimental Psychology: General

Lisa K. Fazio, Vanderbilt University
Nadia M. Brashier and Elizabeth J. Marsh, Duke University
Keith B. Payne, University of North Carolina at Chapel Hill

Posted: October 5, 2015
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