Judgment under Uncertainty: Heuristics and Biases (Availability)
Amos Tversky & Daniel Kahneman · 1974
"People estimate how frequent or likely something is by how easily examples come to mind — which means vivid, recent, or heavily-reported events get judged as far more common than they actually are, while common but unremarkable events get systematically underestimated."
The mechanism is a mental shortcut: ease of recall stands in for actual frequency. Since dramatic events, plane crashes, shark attacks, terrorist incidents, get disproportionate media coverage and are more memorable, they come to mind faster than statistically far more common but mundane risks, like heart disease or ordinary car accidents, which distorts how people rank real-world danger.
Tversky and Kahneman showed this experimentally by asking people to judge whether more English words start with the letter K or have K as the third letter; nearly everyone said the former, even though the true answer is the opposite, because words starting with a letter are simply easier to retrieve from memory than words with that letter in the third position. The heuristic is efficient, since recalling examples really is correlated with frequency most of the time, which is exactly why it's hard to notice when it fails — it only breaks down specifically when memorability and actual frequency come apart, as they do for anything heavily covered by media.
What does the availability heuristic cause people to do?
Read more about the topic
The explanation above is written with AI assistance. These are the originals — go to them to check it.
- Judgment under Uncertainty: Heuristics and Biases (full paper)Tufts University
Judgment under Uncertainty: Heuristics and Biases (Anchoring)
"When estimating an unknown quantity, people rely heavily on the first number they're exposed to, the anchor, and adjust insufficiently away from it — even when that anchor is arbitrary, irrelevant, or explicitly randomly generated."