Myth-Making: Say It Often, People Will Believe

People doubt vaccine safety or evolution because they hear it so often.

ByABC News
August 30, 2011, 4:43 PM

Sept. 1, 2011 — -- The United States is reeling from a hurricane, drought, heat waves, and even an earthquake in Virginia. And we're already well into a nasty national election campaign.

Now is the time to get those rumors flying, because science is proving what most of us already know: If you say something often enough, people will believe it, even if it seems too far out at first to be taken seriously.

Why are people so eager to embrace myths, even if there is not a shred of evidence to support them? Why are so many so eager to believe the unbelievable?

It's no surprise that myths are common in politics, but they invade every field of thought, including science, even when they have been shown to be false. They spread at lightning speed in these days of social media, 24-hour television news, and instant global communications. They aren't harmless.

And it's so easy to do.

Here's how it's done, according to a new mathematical model for rumor-mongering offered by a physicist turned linguist, Lukasz Debowski, although there's no reason to believe he intentionally planned to throw fuel on the rumor mill. His prescription, developed through incredibly complex mathematics, is this:

Say it often. Keep it short.

That formula is backed by research among psychologists and sociologists who have studied the spread of myths in recent years, including psychologist Norbert Schwarz of the University of Michigan, who found that it doesn't take many believers to spread a rumor. A single voice, heard often enough, can sound like a chorus. And it doesn't seem to make much difference whether or not that single voice is credible.

In his research, Schwarz used a flier put out by the Centers for Disease Control that was intended to knock down rumors that flu shots were harmful. Within 30 minutes after they read the flier, a fourth of the older participants in the study believed the false rumors were true, and that rose to 40 percent in just three days. Younger people fared no better. So a flier that was designed to discredit rumors actually reinforced them.

If you think that's exceptional, ask a few friends if they think flu shots can cause autism.

Gregory Poland of the Mayo Clinic in Rochester, Minn., has reason to view that with alarm. His clinic issued a news release Tuesday warning that measles are making a comeback in this country and Europe because many parents believe the inoculation has been linked to autism.

That belief grew out of a paper published in 1998 by the British medical journal, The Lancet. It has since been retracted because it was found to be based on fraudulent research. So it clearly is not true, even though some celebrities have urged parents to refuse to immunize their children against the potentially deadly virus. Thus, the myth survives clear scientific evidence.

Some scientists, including pediatricians Aaron Carroll and Rachel Vreeman of the Indiana University School of Medicine, have spent years debunking myths. It is not true that cold weather can give you a cold (colds are caused by a virus, not temperature). Frogs do not give you warts. Chewing gum does not stay in your stomach for seven years.

But the question persists: Why do so many continue to believe claims that have no basis in fact?