Heuristic
A mental rule of thumb that makes judgment fast and frugal.
What it means
A heuristic is a simple, efficient cognitive rule that the mind uses to form judgments and reach decisions quickly, deliberately trading some accuracy for speed and reduced effort. Heuristics are central to two complementary research traditions that interpret them differently: in the Kahneman–Tversky 'heuristics and biases' program they are shortcuts that usually serve well but produce systematic, predictable errors when their cues mislead, while in Gigerenzer's 'fast and frugal' program they are adaptive tools that can match or beat complex statistical models, especially under uncertainty and scarce information. The reconciling idea is ecological rationality: a heuristic is neither smart nor dumb in the abstract, but only relative to how well its structure fits the environment in which it is used. They operate largely automatically and underlie much of intuitive expertise as well as many documented biases. Heuristics matter because they describe how real, boundedly rational agents actually decide, and understanding them is the foundation both for predicting error and for designing simple decision aids that exploit, rather than fight, how the mind works.
Examples
The recognition heuristic — 'if you recognize one option but not the other, judge the recognized one as larger or better' — often works surprisingly well, until recognition stops tracking the truth.
Buying olive oil, most shoppers take the second-cheapest bottle rather than compare thirty labels — a rule that sacrifices a little accuracy and saves ten minutes in the aisle.
A fielder catching a high ball computes no trajectory; they run so the ball stays at a fixed angle in their gaze — a crude rule that fits the physics closely enough to work.
First described in Tversky & Kahneman; Gigerenzer's 'fast and frugal' program.