The availability heuristic is the tendency to estimate the probability of something happening based on how many examples readily come to mind.
Some examples of this:
- After seeing several news reports of car thefts in your neighborhood, you might start to believe that such crimes are more common than they are.
- You might believe that plane crashes are more common than they really are because you can easily think of several examples.
- Smokers who have never known someone to die of a smoking-related illness, for example, might underestimate the health risks of smoking.
- In contrast, if you have two sisters and five neighbours who have had rare cancer, you might believe it is even more common than statistics suggest.
It is essentially a mental shortcut designed to save us time when we are trying to determine risk. The problem with relying on this way of thinking is that it often leads to poor estimates and bad decisions.