The Availability Heuristic

Nadia Memari, Editor/Journalist

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Do you remember reading that article about the ten year old girl who was abducted in broad daylight? Or the ones about those terrifying shark attacks, plane crashes, and peculiar deaths? Did they all make you suddenly and irrationally cautious?

Chances are, this has happened to you before – and way too many times to count! Although it’s irrational, it happens to everyone.

Now, what do you think is more likely to kill you? Vending machines or shark attacks? Obviously, none of us hear stories about intimidating vending machines, but we can probably recall countless movies, articles, documentaries, and tales about the threat that sharks pose. For this reason, most people would choose the latter option, which ,you probably have guessed by now, is wrong. In the U.S., vending machines cause about two to three deaths per year, while there is only one death every two years from a shark attack. With these statistics in mind, however, you still might not feel the need to be as cautious around vending machines as you would be in the ocean. But there are reasons why we think this way.  

What’s the explanation behind this?

It’s all due to the availability heuristic.


What is the availability heuristic?

Before defining the availability heuristic, it is important to know what a heuristic is. We can break the term in half. Availability: the ease with which a particular idea can be brought to mind. Heuristic: mental shortcuts used to solve problems and make decisions quickly. These shortcuts – sometimes imperfect and irrational – allow people to function without continually stopping to think about their next actions. Although they can prove to be very useful, they often lead to few errors in thinking. Such errors are known as cognitive biases; the availability heuristic would be one example of many mental shortcuts that inevitably lead to errors.

The availability heuristic was first discovered by psychologist Daniel Kahneman in 1973, and he defined it as “the process of judging frequency by the ease with which instances come to mind.” Put in more simple terms, it refers to when one guesses the likelihood of an event happening based on how easily he can remember examples of the event. Kahneman claims that “this is largely determined by the extent of coverage in the media.”

Like other judgement heuristics, this one replaces one question with another, allowing the person to reach an answer more quickly. The question is, “how common or important is this event?” yet to answer quicker, we ask, “how easily can I remember instances of the event?” Obviously, substituting one question for another will lead to unavoidable errors, or biases.

Often times, we misjudge the frequency of events that happened recently – ones that have either happened to ourselves or others. This, in part, occurs as a result of the limitations in our memory. Personal experiences, pictures, and vivid examples are more available to us than incidents that happen to others, or words and statistics. Dramatic events, such as plane crashes, also temporarily increase the availability of its category. It is likely that after hearing a recent news report of a plane crash, there will be a change in your feelings about the safety of flying.

Examples of the heuristic:

  •  Not feeling the need to get a flu shot since none of your acquaintances got it last year
  •  Exaggerating the frequency of Hollywood divorces since you can easily remember instances of it occurring
  •  Believing the crime rate is higher than it really is after you were robbed
  • Thinking that smoking isn’t that dangerous because your grandfather smoked and lived until he was 105
  • Hearing a noise at 12 AM and fearing for your life after watching the movie “IT”
  • Seeing news stories about child abductions and starting to think that these instances are common. As a result, you refuse to let your child play alone outside and never let him leave your sight

All situations share one main thing in common: they are guesses of frequency, based on how easily examples of the event can be remembered.


Why is it important?

We’ve probably spent more time than we’d like to admit reading useless, but fascinating, facts on the internet – or at least I have (did you know that sharks were here on Earth before trees?) Knowledge of the availability heuristic is not useless, however. In fact, although it might be just as interesting, it’s quite the opposite of useless! By becoming aware of when you or someone else might be experiencing the bias, you might be able to prevent troublesome resulting situations. Although there’s a very strong emphasis on might.

Because of the bias, our perceptions of risk may be in error and we might worry about the wrong things. While it’s true that a temporary change of feeling toward the safety of flying may not be that harmful, the availability heuristic can cause beliefs that lead to much worse problems. Individuals might underestimate the probability of contracting sexually transmitted diseases from unprotected sexual intercourse, for example, because a friend might have never used protection and turned out to be fine. Of course, the risk is actually very high, and this belief could likely result in a significant consequence.

But your experience of the bias does not just affect you, it also affects your partners. Studies suggest that awareness of the availability bias is what contributes to peace in marriages, and likely in other joint projects as well. When spouses were asked to give a percentage of how much they contributed to keeping the house tidy, the self-estimated contributions added up to much more than 100% – they all assumed that they helped more than the other person in the relationship.

The bias, however, isn’t always self-serving. In addition to helping, individuals also believed that they started more fights (although to a smaller extent). The same bias contributes to why so many members of collaborative groups claim to have done the most work out of them all, and that others are nowhere near as grateful as they should be for their individual contributions. When several people all feel that their contributions aren’t recognized enough, tension arises.

The reasoning behind these beliefs?

One’s own efforts are seen much more clearly than efforts made by others. This difference in availability causes a difference in judged frequence.


So, can I avoid it?

The good news is, with enough awareness, you can, to some extent, prevent collaborative group tension, tension in marital relationships, and even the contraction of disease! The bad news is, it’s a quite tiresome bias to resist, and you probably won’t destroy it completely. An effort must be made to rethink your impressions and intuitions. Asking yourself questions such as, “is my belief that teen theft is a major problem due to the recent instances of it occurring?” might provide assistance for the bias resistance. Maintaining your vigilance toward the availability heuristic is, no doubt, a chore – but it’s an entirely possible one.  

So, if you ever read an article about plane crashes and start to regret your flight plans to Jamaica, just know that the fear is irrational and due to the availability heuristic – and that you’re much more likely to die on your drive to the airport.


Sources : Thinking Fast and Slow by Daniel Kahneman

                Psychology 101 by Paul Kleinman