“Will a major storm devastate a small island in the near future?” An example of the availability heuristic.

Do you think a major storm is likely to devastate a small island quite soon? I am no meteorologist but, being a psychologist, I expect that your answer to this question was “yes”.

Two horrific storms are lashing different parts of the world as I write this. The newspapers and websites are full of the devastation in the Philippines and the Eastern USA. You would have been hard pressed not to see the headlines and images of rain, wind and landslides.

So, when I asked if you thought a major storm was likely to devastate an island, you found it very easy to conjure up an example or two of major storms. And the ease with which you came up with the examples would have dictated your response. Unless you are a meteorologist, I expect you have no knowledge of the actual likelihood of major storms. You can only go by instinct.

If you find it easy to think of an example of something, you will conclude that it is more likely to happen. If you find it difficult, you will conclude that it is less likely to happen. This is called the availability heuristic, and it is a very common bias affecting our judgement.

It is not the number of examples you can think up which dictates your judgement, but the ease with which you do so. Schwarz et al demonstrated this in an experiment in 1991.Some of the participants were asked to come up with 6 examples of when they had been assertive, and others were asked to come up with 12 examples. Those who only thought of 6 instances then considered themselves more assertive than those who thought of 12. This seems, at first, illogical, but is the availability heuristic at work.

Those who had to think of 12 examples struggled with the last few. It was difficult to come up with as many as they were asked for. This difficulty led them to believe that they were not assertive. Those who only had to think of a few examples found it quite easy, so they concluded that they were indeed assertive.

So your answer to whether you thought it likely a major storm would devastate an island is not so much an indication of your meteorological knowledge. It tells me more about your exposure to recent news outlets.

Find out more about the way the brain fools us in my book, Bias Beware, available here.