The Crazy Power of Repetition

2 0 3,216

“All effective propaganda must be limited to a
very few points and must harp on these in slogans.”
~ Adolf Hitler, Mein Kampf, 1926

Among psychology’s most reliable phenomena is the power of mere repetition. It comes in two forms, each replicated by psychological research many times in many ways.

Repetition Fosters Fondness

We humans are naturally disposed to prefer what’s familiar (and usually safe) and to be wary of what’s unfamiliar (and possibly dangerous).

Social psychologists led by the late Robert Zajonc exposed the power and range of this mere exposure effect. In study after study, the more frequently they showed people unfamiliar nonsense syllables, Chinese characters, geometric figures, musical selections, artwork, or faces, the better they liked them. Repetition breeds liking.

Mere exposure also warms our relationships. As strangers interact, they tend to increasingly like each other and to stop noticing initially perceived imperfections or differences. Those who come to know LGBTQ folks almost inevitably come to accept and like them. By three months, infants in same-race families come to prefer photos of people of their own (familiar) race. We even prefer our own familiar face—our mirror-image face we see while brushing our teeth, over our actual face we see in photos.

Advertisers understand repetition’s power. With repetitions of an ad, shoppers begin to prefer the familiar product even if not remembering the ad.

Indeed, the familiarity-feeds-fondness effect can occur without our awareness. In one clever experiment, research participants focused on repeated words piped into one earpiece while an experimenter simultaneously fed a novel tune into the other ear. Later, they could not recognize the unattended-to tune—yet preferred it over other unpresented tunes. Even amnesia patients, who cannot recall which faces they have been shown, will prefer faces they’ve repeatedly observed.

Repetition Breeds Belief

As mere exposure boosts liking, so mere repetition moves minds. In experiments, repetition makes statements such as “Othello was the last opera of Verdi” seem truer. After hearing something over and over, even a made-up smear of a political opponent becomes more believable. Adolf Hitler understood this illusory truth effect. So did author George Orwell. In his world of Nineteen Eighty-Four, the population was controlled by the mere repetition of slogans: “Freedom is slavery.” “Ignorance is strength.” “War is peace.” And so does Vladimir Putin, whose controlled, continuous, and repetitive propaganda has been persuasive to so many Russians.

Barack Obama understood the power of repetition: “If they just repeat attacks enough and outright lies over and over again . . . people start believing it.” So did Donald Trump: “If you say it enough and keep saying it, they’ll start to believe you.” And he did so with just the intended effect.

What explains repetition’s persuasive power? Familiar sayings (whether true or false) become easier to process and to remember. This processing fluency and memory availability can make assertions feel true. The result: Repeated untruths such as “taking vitamin C prevents colds” or “childhood vaccines cause autism” may become hard-to-erase mental bugs.

But can mere repetition lead people to believe bizarre claims—that a presidential election was stolen, that climate change is a hoax, that the Sandy Hook school massacre was a scam to promote gun control?

Alas, yes. Experiments have shown that repetition breeds belief even when people should know better. After repetition, “The Atlantic Ocean is the largest ocean on Earth” just feels somewhat truer.

Even crazy claims can seem truer when repeated. That’s the conclusion of a new truth-by-repetition experiment. At Belgium’s Catholic University of Louvain, Doris Lacassagne and her colleagues found that, with enough repetition, highly implausible statements such as “Elephants run faster than cheetahs” seem somewhat less likely to be false. Less extreme but still implausible statements, such as “A monsoon is caused by an earthquake” were especially vulnerable to the truth-by-repetition effect.

For those concerned about the spread of oft-repeated conspiracy theories, the study also offered some better news. Lacassagne found that barely more than half of her 232 U.S.-based participants shifted toward believing the repeated untruths. The rest knew better, or even shifted to greater incredulity.

At the end of his life, Republican Senator John McCain lamented “the growing inability, and even unwillingness, to separate truth from lies.” For psychology educators like me and some of you, the greatest mission is teaching critical thinking that helps students winnow the wheat of truth from the chaff of misinformation. Evidence matters. So we teach our students, “Don’t believe everything you hear.” And, after hearing it, “Don’t believe everything you think!”

(For David Myers’ other essays on psychological science and everyday life, visit Follow him on Twitter: @davidgmyers.)

Tags (1)
About the Author
David Myers has spent his entire teaching career at Hope College, Michigan, where he has been voted “outstanding professor” and has been selected by students to deliver the commencement address. His award-winning research and writings have appeared in over three dozen scientific periodicals and numerous publications for the general public. He also has authored five general audience books, including The Pursuit of Happiness and Intuition: Its Powers and Perils. David Myers has chaired his city's Human Relations Commission, helped found a thriving assistance center for families in poverty, and spoken to hundreds of college and community groups. Drawing on his experience, he also has written articles and a book (A Quiet World) about hearing loss, and he is advocating a transformation in American assistive listening technology (see