We estimate how likely or common something is by how easily examples spring to mind — not by actual frequency. Vivid, recent, emotional events feel common; quiet, frequent ones feel rare. So our sense of risk tracks the news, not reality.
The availability heuristic: we judge how likely or frequent something is by how easily examples come to mind — so vivid, recent, or emotional events feel far more common than they actually are.
Are there more words that start with 'r' or have 'r' as the third letter? Most people say the first — because starting-with-r words are easier to call up — but the third-letter ones are far more common. We don't count; we estimate by how easily examples come to mind. Kahneman and Tversky called this the availability heuristic.
Usually it's a fine shortcut — common things are often easy to recall. But it breaks whenever ease-of-recall and actual frequency come apart. Plane crashes are vivid and heavily reported, so they feel risky, while car crashes — vastly more deadly — feel mundane. After seeing news of a shark attack or a kidnapping, people overestimate those risks for weeks. The media doesn't report what's frequent; it reports what's dramatic, and drama is exactly what's 'available.'
The correction is to notice when a judgment is riding on a vivid memory rather than data, and then go find the base rate — the actual numbers. When you catch yourself thinking 'this happens all the time' or 'that's so dangerous,' ask: is that the real frequency, or just what's easy to picture? Your fear is tracking memorability; reality is tracking statistics.
Your gut sense of what's risky, common, or likely is built from whatever's vivid and recent — so without checking base rates, you'll fear the wrong things and miss the quiet ones that actually matter.
It's not 'your memory is unreliable, ignore your instincts.' Availability is usually a useful shortcut — common things often are easy to recall. The bias only appears when memorability and real frequency diverge (drama, recency, emotion). The fix is checking base rates in those specific cases, not distrusting all intuition.
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