Science: If You Want To Make A Lie Seem True Keep Repeating It

Official White House Photo by Joyce N. Boghosian / Public Domain


Even hearing repeatedly that a certain fact is wrong can lead people to accept it as true.

According to science, the way to get people to believe a lie is to tell it over and over and over again. This strategy works, Wired explained in 2017, because of something called the “illusory truth effect.”

  • The illusory effect is “a glitch in the human psyche that equates repetition with truth,” and Wired noted that “Marketers and politicians are masters of manipulating this particular cognitive bias.”
  • The publication offered a couple of examples that were relevant at the time:

President Trump is a "great businessman," he says over and over again. Some evidence suggests that might not be true. Or look at just this week, when the president signed three executive orders designed to stop what he describes—over and over again—as high levels of violence against law enforcement in America. Sounds important, right? But such crimes are at their lowest rates in decades, as are most violent crimes in the US. Not exactly, as the president would have it, "American carnage."

  • No matter the degree of truth in either of Trump’s statements, people are more likely to believe them simply by hearing them repeated.
  • Psychologist Lynn Hasher of the University of Toronto, whose research team first noticed the effect in the 1970s, said, "Repetition makes things seem more plausible. And the effect is likely more powerful when people are tired or distracted by other information."
  • This effect is also responsible for the success of fake news, Wired noted, pointing to Central Washington University research study from 2012.

It's also a staple of political propaganda. It's why flacks feed politicians and CEOs sound bites that they can say over and over again. Not to go all Godwin's Law on you, but even Adolf Hitler knew about the technique. "Slogans should be persistently repeated until the very last individual has come to grasp the idea," he wrote in Mein Kampf.

Why does it work?

  • “The effect works because when people attempt to assess truth they rely on two things: whether the information jibes with their understanding, and whether it feels familiar,” Wired wrote. “The first condition is logical: People compare new information with what they already know to be true and consider the credibility of both sources.”
  • However, researchers have found that familiarity sometimes trumps rationality, even to the degree “that hearing over and over again that a certain fact is wrong can have a paradoxical effect. It's so familiar that it starts to feel right.”
  • In the end, “rationality can be hard. It takes work. Your busy brain is often more comfortable running on feeling.”

So how can people protect themselves from falling prey to the illusory effect?

As with any cognitive bias, the best way not to fall prey to it is to know it exists. If you read something that just feels right, but you don't know why, take notice. Look into it. Check the data. If that sounds like too much work, well, facts are fun.

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