Our senses are hopeless at calculating risk

We overestimate danger when we're not in control, such as flying as a passenger in an aeroplane.
We overestimate danger when we’re not in control, such as flying as a passenger in an aeroplane.
Humans are irrational beings. Smoking kills 480,000 people per year in the United States, while an average of 170 lives are lost to terrorism each year in the same country. Counterintuitively, terrorism receives more media attention than smoking despite having a relatively tiny risk because we’re predisposed to fear dangers imposed by other people more than dangers with which we choose to engage ourselves.

Another great example is aeroplane crashes. Airlines today have an excellent safety record and flying is usually the safest mode of transport (safer than making the same journey by road or rail). We overestimate the dangers of flying on an aeroplane because someone else is in control.

Conversely, because summer heat waves are a natural phenomenon, we’re prone to underestimating their danger: tens of thousands of people die from excessive summer heat each year in the United States alone.

Irrational: we worry about terrorist attacks more than summer heat waves

Our ‘perceived risk’ almost never matches the ‘actual risk’. In the bubble chart below, the area of the circles above the line represent how much we worry about each risk. The area of the circles below the line represents the actual size of the risk in terms of how many people are harmed each year. In many cases, there is a huge disparity between ‘perceived risk’ and ‘actual risk’.

Our perception of risk almost never matches the actual size of the risk. Adapted from work by Susannah Ertrich.
Adapted from work by Susannah Ertrich
The table below shows the factors that increase and decrease our perceptions of risk.
table1 risks template chemicals

Let’s evaluate two examples. First, smoking:

table2 risks template chemicals

Conclusion: people are predisposed to underestimate the risks of smoking (9:1)

Second example: azodicarbonamide (dough improver) added to bread

table3 risks template chemicals

Conclusion: people are predisposed to overestimate the risks of adding azodicarbonamide to bread (1:9)

This strange psychological quirk is one of the roots of chemophobia that I discuss much further in my upcoming book, Fighting Chemophobia (coming out late 2017).

Try it yourselves: use the table to find out whether we’re likely to over-fear or under-fear aeroplane crashes, climate change and parabens in cosmetics. You’ll find that we overestimate the risks of chemical ingredients in our food and products not because they necessarily pose any danger, but because we have this strangely irrational way of assessing risk in the world around us. ♦

3 thoughts on “Our senses are hopeless at calculating risk

  1. While I get where you’re going with this post, your argument is weak, professor. Terrorist attacks get more media coverage than smoking for a number of simple reasons. For example, smoking doesn’t cause people to jump out of the window, a HUNDRED stories off the ground, to avoid melting to death because some dope flew a plane into the building you were working in…. all in the name of a profit.

    Another example, smoking causes lung cancer and possibly death, usually later in life, say the seventies or eighties. It’s a quick death, yes, but not quite as quick and spectacular as being ripped to shreds by nails and ball bearings because a follower of Allah decided to blow himself, and you, up…. All because they don’t like the fact that you’re free to not follow Allah and blow yourself up.

    I could go on, but I think you can get the gist.

    Finally, smoking has gotten enough coverage over the last five decades that everyone, except a select handful of pygmies and natives (who don’t even know what filtered cigarettes are), knows it’s “bad for you”. At this point, we get it.


  2. It’s too bad they left out death by automobile ( except for those involving pedestrians). It’s not just the 30 000+ killed by accidents in the US alone ( over a million worldwide). But fossil-fuel powered-cars also release carbon monoxide, NOx, PM 2.5 pollution, and of course greenhouse gases— both CO2 and AC coolants. Lots of risk associated with those compounds. And unfortunately very little perceived risk, especially with special interest groups in the US still polluting the truth.


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