Every day, people make countless decisions, from choosing a meal to approaching a work problem. Individuals are unable to make perfect decisions due to limitations such as incomplete information, finite cognitive resources, and time constraints. Individuals frequently depend on heuristics to manage these limitations.

The availability heuristic is a mental shortcut people use to simplify decision-making by relying on information that is easy to recall. While this can be helpful for quick judgments, it can also lead to misperceptions when vivid or recent experiences are given more weight than actual probabilities. For example, David recently heard about a lightning strike that caused a wildfire near a hiking trail. Although this type of incident is statistically rare, the vivid imagery of the event sticks with him. David's friends suggested a hike, but he refused, believing that there was a substantial risk of being struck by lightning. Based on the availability heuristic, this judgment overlooks the likelihood of encountering such an event is extremely low compared to other more common risks, like dehydration or a sprained ankle.

People tend to overestimate how often rare but impactful events occur due to the availability heuristic. For instance, after watching extensive media coverage of a train derailment, commuters might believe train travel is inherently unsafe, even though it remains one of the safest modes of transportation. This bias comes from how vividly the event is remembered, not how likely it actually is.