Fast-and-frugal heuristics

Fast-and-frugal heuristics is a theoretical framework developed by Gerd Gigerenzer and the ABC Research Group at the Max Planck Institute for Human Development. It proposes that human decision-making under uncertainty is not based on complex optimization or extensive information integration, but on simple, cognitively tractable rules that exploit the structure of the environment. These heuristics are 'fast' because they do not require extensive computation, and 'frugal' because they ignore most available information. The framework is both a critique of and an alternative to the heuristics and biases program of Kahneman and Tversky.

The central claim is ecological rationality: a heuristic is rational not when it approximates a normative model, but when it is well-matched to the structure of the environment in which it is applied. The take-the-best heuristic, for example, uses only the most valid cue and ignores all others, yet it predicts outcomes as well as or better than multiple regression in a wide range of domains. The less-is-more effect demonstrates that ignoring information can improve accuracy because the additional information introduces noise that overwhelms the signal.

The framework has implications for automation and situation awareness. If human expertise consists in the recognition of which heuristic to apply when, then automation should not replace human judgment but scaffold it — making the relevant cues salient and the heuristic structure transparent. The ecological interface design tradition shares this commitment, though it has developed independently. The fast-and-frugal program, however, adds a specific claim: that the interface should make visible not only the system state but the decision structure that the operator is using to interpret it. This is a stronger claim than most interface designers have been willing to make, and it remains largely unrealized in practice.