# When False Claims Are Repeated, We Start To Believe They Are True



## David Baxter PhD (Sep 12, 2019)

*When False Claims Are Repeated, We Start To Believe They Are True — Here’s How Behaving Like A Fact-Checker Can Help*
By Matthew Warren, _BPS Research Digest_
Sept 12, 2019

 If you hear an unfounded statement often enough, you might just start  believing that it’s true. This phenomenon, known as the “illusory truth  effect”, is exploited by politicians and advertisers — and if you think  you are immune to it, you’re probably wrong. In fact, earlier this year  we reported on a study that found people are prone to the effect regardless of their particular cognitive profile.

 But that doesn’t mean there’s nothing we can do to protect ourselves against the illusion. A study in _Cognition_  has found that using our own knowledge to fact-check a false claim can  prevent us from believing it is true when it is later repeated. But we  might need a bit of a nudge to get there.

  The illusory truth effect stems from the fact that we process  repeated statements more fluently: we mistake that feeling of fluency  for a signal that the statement is true. And the effect occurs even when  we should know better — when we repeatedly hear a statement that we  know is wrong, for instance, like “The fastest land animal is the  leopard”. But Nadia Brashier at Harvard University and colleagues  wondered whether asking people to focus on the accuracy of a statement  could encourage them to use their knowledge instead, and avoid relying  on feelings of fluency.

 In the initial study, the team first asked 103 participants to read  60 widely-known facts, some of which were true (e.g. “The Italian city  known for its canals is Venice”), and some of which were false (e.g.   “The planet closest to the sun is Venus”). One group rated how  interesting each statement was, while the other rated how true it was.  Then in the second part of the study, both groups saw the same 60  statements along with 60 new ones — again a mixture of true and false —  and rated their truthfulness.

 The researchers found that participants who had focused on how  interesting the statements were in the first part of the study showed  the illusory truth effect: they subsequently rated false statements  which they had already seen as more true than false statements which  were new. But the group that had initially focused on the accuracy of  the statements didn’t show this effect, rating new and repeated false  statements as equally true.

 This finding suggests that using our own knowledge to critically  analyze a statement when we originally encounter it may inoculate us  against the illusory truth effect. And this seems to have fairly  long-lasting effects: in another experiment, the team found that  participants who had initially focused on the accuracy of the  statements still showed no sign of succumbing to the illusory truth  effect two days later.

 But considering the accuracy of a statement is only useful if we  already have appropriate knowledge (e.g. that the closest planet to the  sun is Mercury and not Venus). In further studies, the team found that  rating the truthfulness of more obscure false statements which  participants didn’t know much about, such as “The twenty-first U.S.  president was Garfield,” didn’t later protect against the illusory truth  effect. It would be interesting to know whether fact-checking against  external sources like the internet or reference books — which requires  more effort than simply using our own knowledge — is effective at  combating the illusion in these cases.

 Still, simply having the background knowledge needed to counter false  claims is not always enough, say the authors — their results suggest  people may need to be “nudged” into actually using that knowledge.  “Education only offers part of the solution to the misinformation  crisis; we must also prompt people to carefully compare incoming claims  to what they already know,” they write.
 – An initial accuracy focus prevents illusory truth


----------

