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Our skewed perception of health risks (why fear often trumps reason)

You are more likely to be trampled by cattle than eaten by a shark.
CC/Flickr/Patrick Gage
You are more likely to be trampled by cattle than eaten by a shark.

Discover magazine put up on its website this week a useful article (from an earlier print edition) about how we humans often have a skewed perception of health risks — specifically, how we tend to “fear rare threats such as shark attacks while blithely ignoring far greater risks like unsafe sex and an unhealthy diet.”

The article, written by Jason Daley, opens with last spring’s run on potassium iodide. People frantically stripped store shelves of the obscure supplements, hoping it would protect their thyroids from radiation when the fallout from the Fukushima nuclear disaster reached western United States.

Within a few days, the price of a bottle of the pills jumped from $10 to $200 — even though, as the Environmental Protection Agency quickly pointed out, the amount of radiation that would hit the West Coast from Fukushima was equivalent to 1/100,000 of the exposure an individual receives during a round-trip international flight.

Fear had trumped reason.

Our fears confirm our biases
In his article, Daley explains what scientists have discovered about why we often fear rare health risks while ignoring common ones. One factor is confirmation bias, which, says Daley,

leads us to prefer information that backs up our current opinions and feelings and to discount information contradictory to those opinions. We also have tendencies to conform our opinions to those of the groups we identify with, to fear man-made risks more than we fear natural ones, and to believe that events causing dread — the technical term for risks that could result in particularly painful or gruesome deaths, like plane crashes and radiation burns — are inherently more risky than other events.

Another factor behind our distorted perception of risk is a psychological phenomenon known as the availability heuristic: The easier it is for us to imagine something, the more likely we are to believe it threatens us. As Daley points out, we can easily imagine the fearful sight and sound of a tornado ripping through our house. It’s much harder — and much less emotional — to conjure up the image of fat, cholesterol and other substances slowly accumulating in our arteries.

“Twisters feel like an immediate threat, although we have only a 1-in-46,000 chance of being killed by a cataclysmic storm,” writes Daly. “Even a terrible tornado season like the one last spring typically yields fewer than 500 tornado fatalities. Heart disease, on the other hand, which eventually kills 1 in every 6 people in this country, and 800,000 annually, hardly even rates with our gut.”

Putting things in perspective
I don’t agree with all of Daley’s premises. I think there’s a difference between health risks, no matter how small, that are imposed on us without our consent (from a nuclear power plant built near our homes, for example) and those we choose to take on ourselves (drinking sodas daily). But Daley scatters some useful examples throughout his article of how irrational our risk perception sometimes becomes — examples that can help us put health risks into perspective. Here are two:

  • “The Office of National Drug Control Policy reports that prescription drug overdoses have killed more people than crack and heroin combined did in the 1970s and 1980s. Law enforcement and the media were obsessed with crack, yet it was only recently that prescription drug abuse merited even an after-school special.”
  • “News coverage of a shark attack can clear beaches all over the country, even though sharks kill a grand total of about one American annually, on average. That is less than the death count from cattle, which gore or stomp 20 Americans per year.”

You’ll find Daley’s article on the Discover website.

Comments (2)

  1. Submitted by Phil Dech on 10/06/2011 - 11:57 am.

    This reminds me of the time a few years back when a woman chided me for drinking water from a tap, because of all the chemicals that might be in it – right before she went out and smoked a cigarette.

  2. Submitted by Bill Gleason on 10/07/2011 - 09:59 am.

    Irrational risk perception is often stimulated by fear mongers who have an ax to grind.

    Two examples would be the pharmaceutical industry and people who sell disease diagnostics.

    No wonder people are confused and sometimes act in ways that appears to be irrational.

    One other thing to think about. Death by volcano is pretty rare. Does this mean you shouldn’t worry about it if you live next to one?

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