Psychology › Thinking, memory & biases › Heuristics and biases
Availability heuristic
1973· Finding or experiment
Well replicatedStrong, repeated evidence.
We judge how common or likely something is by how easily examples come to mind.
See it on the Psychology map →What it says
In 1973 Tversky and Kahneman asked whether letters such as K more often start English words or appear third. Most said first, because words starting with K are easier to recall; in fact third-position K is more common. Vivid, recent or heavily reported events feel more frequent: people overestimate deaths from plane crashes and tornadoes and underestimate those from diabetes and strokes.
Why it matters
It skews risk judgment: people buy flood insurance after a flood and let it lapse as memories fade, and investors overreact to recent market news.
Think of it like
Like judging a neighborhood's crime rate from last week's headlines rather than the police data.
The evidence
Well replicated in its core form across many studies of frequency and risk judgments. Norbert Schwarz's 1991 work suggested the feeling of easy recall, not the number of examples, drives the judgment.
Open questions
Outside the lab it is hard to separate availability from media coverage and personal fears, so how much it explains real-world risk errors is uncertain.
Connections (2)
▸Availability heuristic is a classic example of Heuristics and biasesWell replicated
The connection
Availability is one of the three original shortcuts in the 1974 framework: a sensible rule, since common things usually are easier to recall, that misfires when ease of recall reflects vividness, recency or media coverage rather than true frequency.
Who showed it and when
Named by Tversky and Kahneman in a 1973 paper in Cognitive Psychology, then featured in their 1974 Science article.
The evidence
It appears in both founding papers and has been reproduced in many experiments on frequency and risk judgments since.
Open questions
Critics say 'availability' is too loose a label and can be fitted to almost any result after the fact.
▸Availability heuristic was identified by Daniel Kahneman and Amos TverskyWell replicated
The connection
Tversky and Kahneman spotted availability while studying how people estimate frequencies. They designed simple tests, such as the letter-position question and lists mixing famous and less famous names, showing people judge frequency by how easily examples come to mind.
Who showed it and when
Hebrew University and the Oregon Research Institute, early 1970s; published in Cognitive Psychology in 1973.
The evidence
The 1973 paper reports the experiments; Kahneman's memoir and Lewis's The Undoing Project describe how the idea arose.
Open questions
A 1998 repeat of the letter-position task found weaker, inconsistent bias, so some original demonstrations are less solid than the concept itself.