representativeness heuristic
Summary
The representativeness heuristic is a mental shortcut that judges how likely something belongs to a category by how closely it resembles a typical member. It often leads people to neglect base rates, so a good match can seem likelier than a more common category.
Detail
Meaning: The representativeness heuristic is a mental shortcut for judging whether a person or event belongs to a category by how closely it matches one's prototype of that category. It is fast and often reasonable, but it neglects base rates (how common each category is) and sample size. Tversky and Kahneman studied it alongside the availability heuristic.
On the MCAT: A passage describes someone as quiet, tidy and bookish and asks whether that person is more likely a librarian or a farmer. Choosing librarian because of the resemblance, even though far more farmers exist, shows the heuristic. A related example is the gambler's fallacy: after five heads in a row, tails seems due because a mixed sequence looks more typical of randomness. Expect to be asked to name the heuristic, or to identify the information that was neglected.
Common confusion: Students confuse it with the availability heuristic. Representativeness depends on resemblance to a prototype; availability depends on how easily examples come to mind. Neglect of base rates is the error that results, not the heuristic itself.
Sources
- Psychology (Myers)
- Psychology (Schacter, Gilbert, Wegner)
Written for the MCAT and checked before it was published. For study reference only. Spotted an error? Let us know.