In their first study of the availability heuristic, Tversky and Kahneman asked participants to estimate whether English had more words that started with the letter K or more words that had K as the third letter. What do you think?

If you’re like most participants in their study, you might guess that there are more words that start with k than words that have k as the third letter, when in fact this is not the case. The reason you might have misjudged is that you were probably able to bring to mind more examples of words that start with k. We don’t usually bring words to mind based on their third letter, so naturally it was harder to think of those examples. Thinking of words that start with k probably seemed much easier, and as a result you may have felt that these words are more common. The availability heuristic says that we tend to estimate the frequency of events based on how easily we can come up with examples, or how “available” they are to our mind.

This tendency to assume that things which are more easily recalled are more frequent can be seen when we attempt to estimate the likelihood of events like terrorist attacks or plane crashes. Examples of these unfortunate events tend to spring to mind rather easily, and this may cause us to assume that these events occur more frequently than they actually do.

On the other hand, events and dangers which actually are more frequent may not come to mind quite so readily. So parents may fear letting their children walk to school because of highly-memorable news stories of child abductions, even though the risks posed by choking, drowning, or car accidents are far greater. Often it seems that the things we fear might kill us are not the things that are actually likely to kill us. As comedian Norm Macdonald noted, you spend time thinking “gee, I hope a terrorist doesn’t attack and kill me”, when it’s far more likely that your own heart is what will attack and kill you.

This post is an excerpt from Master Introductory Psychology: Complete Edition