The availability heuristic
\ ði \ əˌveɪləˈbɪləti \ hjʊˈrɪstɪk \
The availability heuristic is the reliance on examples that immediately come to mind when forming an opinion.
Heuristics are mental shortcuts that allow decisions to be made in less time and with less effort. They often produce decisions that are good enough for a given purpose, but they can also result in categories of poor judgements, known as cognitive biases.
The availability heuristic is one of the three heuristics identified by Kahneman and Tversky in their seminal work on judgement under uncertainty and relies on the assumption that things that are remembered easily must be important; related cognitive biases arise when the most vivid recollections are not the most relevant for making decisions. For example, assuming that things that happened recently or extreme events that are disproportionately publicized are more likely to happen again than the statistics would imply.
Multiple surveys from around the world (for example, the US and the UK) have found that people, on the whole, underestimate how long they are expected to live. Some commentators believe the availability heuristic, coupled with the media tendency to sensationalize bad-news stories is largely at play in this mis-estimation. Reports of people dying early are widespread whereas reports of people living long healthy lives are not as common.