What Makes Some Lies More Convincing Than the Truth?
Research confirms that repeating even absurd falsehoods makes them believable.
Posted November 5, 2022 | Reviewed by Devon Frye
- How is it that millions of people come to accept conspiracy canards that are demonstrably false? The answer may lie in the illusory truth effect.
- Recently published cognitive research demonstrates that repetition increases the likelihood that people will judge a statement to be true.
- Research results suggest that the illusory truth effect is highly robust and occurs across all levels of plausibility.
- In some contexts, repetition can be a deliberate strategy used to promote known falsehoods.
"A lie travels around the globe while the truth is putting on its shoes." —Usually attributed (inaccurately) to Mark Twain
“Guess what? We have furries* and fuzzies in classrooms,” the Republican candidate for the U.S. Senate in New Hampshire recently informed an assembled collection of his supporters. “They lick themselves, they’re cats. When they don’t like something, they hiss.
"And get this—they’re putting litter boxes, right? Litter boxes for that. I wish I was making it up,” the GOP nominee said. 
Guess what? He was making it up. Or rather repeating it, parroting an absurd and thoroughly debunked online conspiracy, that public schools are accommodating kids who identify as cats by providing them with litter boxes as an alternative to toilets. This hoax has been repeated by no less than 20 Republican politicians, including the Republican gubernatorial nominees of Minnesota and Colorado, and at least several GOP nominees for the House of Representatives.
The above falsehood is of a piece with claims that teachers are “grooming” children for sexual abuse, transgender athletes have proliferated throughout and dominate girls’ sports, Ivermectin (horse dewormer) will protect you from COVID-19, and the 2020 presidential election was stolen.
The Illusory Truth Effect
How is it that millions of people come to accept conspiracy canards that are demonstrably false? It can be explained by a phenomenon known as the illusory truth effect—If something is repeated enough times, it seems more true. Worse, it can happen even if the information is extremely dubious and even if you know better.
Recently published cognitive research demonstrates that repetition increases the likelihood that people will judge a statement to be true—including easily disproven statements, such as “a sari is the short, pleated skirt worn by men in Scotland,” “the Stanley Cup is awarded in soccer,” “more people fly to work than drive to work” and “elephants run faster than cheetahs.”  Moreover, multiple statements at the same time strengthen the illusory truth effect and beliefs in the falsehood. 
That said, when individuals are faced with obviously true or false statements, repetition should have no impact, right? Wrong. In a 2019 study, contrary to that intuition, belief in all statements was increased by repetition. The results suggest that the illusory truth effect is highly robust and occurs across all levels of plausibility—confirming that even highly implausible statements will become more plausible with enough repetition. 
If you simply repeat a falsehood enough—even statements that may seem patently absurd—it's likely that more people will believe it. And the louder and more emphatic these repetitions are, the more believable the absurdities become. This is a way to promote untruths. In some contexts, for specific purposes, it’s a planful strategy to effectively “groom” falsehoods.
That’s how the cat conspiracy got out of the litter box, so to say. According to NBC News, it may have originated in Canada in October 2021, when social media posts began claiming that schools were arranging litter boxes for students who identify as cats. This inane hoax quickly made its way across the border, surfacing at a school board meeting in Michigan, and continued from there, eventually finding a home in some Republican candidates’ talking points. 
Despite having been debunked repeatedly by fact-checkers at major news outlets, this pernicious conspiracy continues to be persistent, having spread to such an extent that it even has its own Wikipedia page.
The only thing that is proven to reduce the influence of the illusory truth effect is to train yourself to consider the reliability of the source and regularly fact-check news items and claims the first time you encounter them. This involves a bit of effort that impressively few people make. And when such a claim fits neatly into your ideological or partisan leanings, you might understandably be even less inclined to fact-check it.
However, determining the accuracy and validity of information that has the potential to affect our lives (to the best of our ability) is an important action—perhaps even a responsibility—whether or not it happens to comfortably coincide with our own worldview. In the same way that when something seems too good to be true, it probably is, when something appears too preposterous to be true, it likely is.
*Furries are a subculture in which people dress up and role-play as anthropomorphic animal characters, and there are conventions where they gather together, sans litter boxes.
Copyright 2022 Dan Mager, MSW
 Henderson, E. L., Simons, D. J., & Barr, D. J. (2021). The Trajectory of Truth: A Longitudinal Study of the Illusory Truth Effect.Journal of Cognition, 4(1), 29. DOI: http://doi.org/10.5334/joc.161
 Fazio LK, Rand DG, Pennycook G. Repetition increases perceived truth equally for plausible and implausible statements. Psychon Bull Rev. 2019 Oct;26(5):1705-1710. doi: 10.3758/s13423-019-01651-4. PMID: 31420808.