The art of thinking · 6 · Judgment, action and error

Heuristics and biases

Also known as: Heuristics-and-biases program, Cognitive biases, Judgmental heuristics

German: Heuristiken und Urteilsverzerrungen

In cognitive psychology, heuristics and biases is the research program, founded by Amos Tversky and Daniel Kahneman, which holds that people judge probabilities and frequencies with simple heuristics — such as availability, representativeness and anchoring — that are often useful but lead to systematic errors (biases) compared with the rules of probability and statistics.

Cognitive psychology
Judgment
Decision making

In one sentence

Heuristics and biases: people judge likelihood with shortcuts such as availability, representativeness and anchoring, causing systematic errors (1974).

Example

After a widely reported crush accident, operators rate that hazard as far more likely than a frequent but unreported one — the vivid case is easier to recall (availability).

What the research shows

Amos Tversky and Daniel Kahneman (1974) described three heuristics. With availability, people judge how frequent or likely an event is by how easily examples come to mind, so vivid or recent events are overestimated. With representativeness, people judge probability by similarity to a stereotype and neglect base rates and sample size. With anchoring and adjustment, an initial value — even an arbitrary one — pulls subsequent estimates toward it. Daniel Kahneman (2011) placed the program in a dual-process framing, in which fast, intuitive judgments (System 1) are only sometimes corrected by slow, deliberate thinking (System 2).

Evidence status

Many of the classic effects are robust: anchoring effects, for example, were replicated across dozens of samples in the Many Labs project (Richard A. Klein and colleagues, 2014), although their size varied with the task. Other effects associated with the wider literature, especially some priming studies cited in popular books, replicated poorly, and Kahneman later acknowledged this for priming. Gerd Gigerenzer (1996) criticized the program for using narrow norms of rationality and vague definitions of the heuristics; his school of ecological rationality argues that simple heuristics often perform well in real environments. Labeling a judgment as a “bias” therefore depends on the standard it is compared with. Long popular lists of “cognitive biases” mix findings of very different strength.

How it applies

Readers judge how relevant a section is and how likely a hazard is with heuristics; recent, vivid or familiar cases weigh more. The glossary “Applied cognitive psychology for information use” takes this up under risk perception and hazard perception. Heuristics describe how readers judge; they do not change the risk, which is determined in the risk assessment. See also bounded rationality and dual-process theory.

External references

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