Availability heuristic

Estimation biases biases

The availability heuristic is when you judge how likely something is by how easily examples come to mind. Vivid or recent events feel more common than they are, so you overestimate their probability. It affects decisions about risk, health, and everyday choices whenever you rely on what you can quickly recall. Related: Anecdotal, Hasty generalization, Misleading vividness.

Examples

  • After several news stories about plane crashes, you overestimate the risk of flying and prefer to drive, even though driving is statistically riskier per mile.

  • You know someone who won the lottery, so you overestimate your own chances and buy more tickets, ignoring how rare wins actually are.

  • A colleague was recently laid off, so you worry that job loss is very likely in your industry even when employment in your sector is stable.

  • You remember one dramatic case of a vaccine side effect and downplay how rare it is compared with the benefits of vaccination.

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