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How to debunk medical (and other scientific) myths

Long-debunked myths about health and medicine are widely — and stubbornly — held. Some can lead to harm, such as the false belief that childhood vaccinations can cause autism. Others usually just waste people’s time and money, such as the mistaken idea that taking vitamins or other supplements provides “added protection” against disease or that a “colon cleansing” eliminates toxins from the body.

But how do you persuade people that such beliefs are based on misinformation? That’s a huge challenge.

In his latest NeuroHacks column for the BBC Future website, British psychologist Tom Stafford explains what two researchers, Stephen Lewandowsky and John Cook, discovered on this topic a few years ago when they were exploring how to counter misinformation on climate change.

Writes Stafford (with British spellings):

The first thing their review turned up is the importance of “backfire effects” — when telling people that they are wrong only strengthens their belief. In one experiment, for example, researchers gave people newspaper corrections that contradicted their views and politics, on topics ranging from tax reform to the existence of weapons of mass destruction. The corrections were not only ignored — they entrenched people’s pre-existing positions.

Backfire effects pick up strength when you have no particular reason to trust the person you are talking to. This perhaps explains why climate sceptics with more scientific education tend to be the most sceptical that humans are causing global warming.

The irony is that understanding backfire effects requires that we debunk a false understanding of our own. Too often, argue Lewandowsky and Cook, communicators assume a ‘deficit model’ in their interactions with the misinformed. This is the idea that we have the right information, and all we need to do to make people believe is to somehow “fill in” the deficit in other people’s understanding. Just telling people the evidence for the truth will be enough to replace their false beliefs. Beliefs don’t work like that.

American Academy of Pediatrics public service announcement
American Academy of Pediatrics public service announcement

What does work? How can people who are scientifically misinformed be persuaded that their beliefs are wrong? Research has shown, says Stafford, that the most important thing you can do is to offer a plausible, alternative explanation — one that will take the place of the myth.

In their “Debunker’s Handbook,” Lewandowsky and Cook offer the following tips (again, with British spellings) for how to do this. These tips are for written efforts at debunking misinformation, but, with a little adaptation, they can be used in conversations as well.

  • Core facts — a refutation should emphasise the facts, not the myth;
  • Explicit warnings — before any mention of a myth, text or visual clues should warn that the upcoming information is false;
  • Alternative explanation — any gaps left by the debunking need to be filled. This may be achieved by providing an alternative causal explanation for why the myth is wrong and, optionally, why the misinformers promoted the myth in the first place;
  • Graphics — core facts should be displayed graphically, if possible.

Be forewarned, however: Attempting to persuade someone that one of his or her long-held beliefs is false is not risk-free. “If you try and debunk a myth,” writes Stafford, “you may end up reinforcing that belief, strengthening the misinformation in people’s mind without making the correct information take hold.”

And don’t forget to take a close look at some of your own long-held notions of scientific truth, he adds. “This debunking advice is also worth bearing in mind if you find yourself clinging to your own beliefs in the face of contradictory facts,” Stafford writes. “You can’t be right all of the time, after all.”

You can read Stafford’s Neurohacks column on the BBC Future website. He also writes the very entertaining and informative MindHacks blog. Lewandowsky and Cook’s “Debunker’s Handbook” can be downloaded for free at skepticalscience.com.

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Comments (6)

  1. Submitted by Ron Gotzman on 11/18/2014 - 04:38 pm.

    That explains it??

    Does this explain why so many readers of MinnPost become so entrenched in their beliefs in spite of factual evidence?

    For example: Myths that are still advanced….

    Myth #1 – you can keep your health care plan and doctor.

    Myth #2 – your health care costs will go down

    Myth #3 – Dayton just raised taxes on the rich

    Quite possibly- it is the effect that if you continually repeat a lie – it will be embraced, or have all the advocates been “gruberized?”

    • Submitted by RB Holbrook on 11/18/2014 - 05:03 pm.

      Continuous repetition

      Is that why conservatives repeat the same tired old talking points again and again? I thought it was an inability to think up something original–now I know it’s just another propaganda trick.

    • Submitted by Dan Hintz on 11/19/2014 - 12:37 am.

      Exhibit A

      Wow, this comment really demonstrates the point of the story.

      My health care costs did go down when I enrolled in Mnsure, as did a lot of people’s. I can show you the premium statements. I expect the vast majority of people complaining (or erroneously claiming things are myths) about Mnsure, aren’t on it. The website was a little buggy, but otherwise its been great.

      I don’t know if the issue is the definition of “rich” as far as tax increaes, but the only tax increase was on the highest earners. The laws enacted in this state aren’t secret – they can be found in books and even on the internet. But somehow, this is just a myth? Um, ok.

      And ok, the claim that you can keep your plan had some holes because some people were getting ripped off by non-conforming plans. I think everyone understands what happened now and the only people repeating that are people opposed to the ACA.

      The reality is that for the most part the ACA has worked very well in places where it has been fully implemented. Unfortunately, some people are so opposed to it, that its success, and any facts about it generally, is of no consequence to them.

  2. Submitted by Nancy Hokkanen on 11/18/2014 - 10:06 pm.

    CDC scientist: Plausible mercury causes “autism-like features”

    Senior CDC scientist Dr. William Thompson was recorded this year admitting that biologic plausibility exists indicating that Thimerosal from vaccines leads to autism-like features in children:

    “You know, in the United States the only vaccine it’s still in is for pregnant women. I can say confidently, I do think thimerosal causes tics. So, I don’t know why they still give it to pregnant women. Like, that’s the last person I would give mercury to. ‘Thimerosal from vaccines cause tics’… you start a campaign and you just make that your mantra.

    “Do you think a pregnant mother would want to take a vaccine that they knew caused tics? Absolutely not! I would never give my wife a vaccine that I thought caused tics.

    “I can say, tics are four times more prevalent in kids with autism. There is biologic plausibility right now to say that thimerosal causes autism-like features.”


    Sometimes topics are considered debunked because lazy reporters copy and paste PR from corporate media and government agencies concealing their data manipulation.

    • Submitted by Dan Hintz on 11/19/2014 - 07:47 am.

      Exhibit B

      And sometimes false claims are debunked because the person who started them was a child abuser who committed fraud and lost his medical license.

    • Submitted by RB Holbrook on 11/19/2014 - 11:55 am.

      Sometimes topics are considered debunked

      when they have been debunked. The vaccine-autism link is a prime example.

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