Availability heuristic
We judge how frequent or likely something is by how easily examples come to mind.
What problem it addresses
It explains why we overestimate striking or recent risks and underestimate the ones we don’t easily remember.
An example
In English, are there more words that start with K or that have K as the third letter?
It is much easier to recall words that start with K. That ease feels like frequency to us.
Why it happens
To estimate, we search for examples in memory.
If they come up easily, we assume they are frequent.
What is recent, striking or repeated comes up first, even if it isn’t more common.
Applications in design
Use it like this
Pair striking cases with baseline data so people can calibrate.
Avoid
Highlighting only extreme cases to make something seem more common or more dangerous.
Don’t fall for it
Before estimating a risk, look for the data, not the example you remember.
81%
What the research says
Participants who, after hearing a list of men’s and women’s names, believed there were more of the sex whose names were famous, even though there were fewer (Tversky and Kahneman, 1973).
Solid evidence. They showed it with several different tasks: letters, names and word lists.
Connections
Authors and works
- 1973
Amos Tversky and Daniel Kahneman
Described the heuristic and tested it in several experiments.
Sources
Original sources
- Tversky, A., & Kahneman, D. (1973). Availability: A heuristic for judging frequency and probability. Cognitive Psychology, 5(2), 207–232. View source: Tversky, A., & Kahneman, D. (1973)
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