Illusory truth effect

The illusory truth effect (also known as the truth effect, the illusion-of-truth effect, the reiteration effect, the validity effect, and the frequency-validity relationship) is the tendency to believe information to be correct after repeated exposure. One science writer has explained it as follows: "Why are so many people convinced that we only use 10% of our brains, or that Eskimos have no words for snow...?" The answer is the truth effect.

This phenomenon was first discovered in 1977 at Villanova University and Temple University. It has in recent years been equated by some researchers with the concept of "truthiness", a term coined by American comedian Stephen Colbert.

The effect was first named and defined following the results in a study from 1977. On three occasions, Lynn Hasher, David Goldstein, and Thomas Toppino presented the same group of college students with lists of sixty plausible statements, some of them true and some of them false. The second list was distributed two weeks after the first, and the third two weeks after that. Twenty statements appeared on all three lists; the other forty items on each list were unique to that list. Participants were asked how confident they were of the truth or falsity of the statements, which concerned matters about which they were unlikely to know anything. (For example, "The first air force base was launched in New Mexico." Or "Basketball became an Olympic discipline in 1925.") Specifically, the participants were asked to grade their belief in the truth of each statement on a scale of one to seven. While the participants' confidence in the truth of the non-repeated statements remained steady, their confidence in the truth of the repeated statements increased from the first to the second and second to third sessions, with an average score for those items rising from 4.2 to 4.6 to 4.7. The conclusion made by the researchers, who were from Villanova and Temple universities, was that repeating a statement makes it appear more likely to be factual.

In 1989, Hal R. Arkes, Catherine Hackett, and Larry Boehm essentially replicated the original study, with similar results, which was published in Europe's Journal of Psychology.

At first, the truth effect was believed to occur only when individuals are highly uncertain about a given statement.

This assumption was challenged by the results of a 2015 study by Lisa K. Fazio, Nadia M. Brasier, B. Keith Payne, and Elizabeth J. Marsh. Published in the Journal of Experimental Psychology, the study suggested that the truth effect can have an impact on participants who actually knew the correct answer to begin with, but who were swayed to believe otherwise through the repetition of a falsehood. For example, when participants encountered on multiple occasions the statement "A sari is the name of the short plaid skirt worn by Scots," some of them were likely to come to believe it was true, even though these same people were able to correctly answer the question "What is the name of the short pleated skirt worn by Scots?"

...
Wikipedia