Baruch Fischhoff

Who they are

The work of Baruch Fischhoff reaches this site through the papers listed below. On this site the name is tied to Hindsight Bias, Outcome Bias, The Illusion of Understanding, The Illusion of Validity, Availability Heuristic, Denominator Neglect.

Key papers

Fischhoff, B. (1975). Hindsight is not equal to foresight: The effect of outcome knowledge on judgment under uncertainty. Journal of Experimental Psychology: Human Perception and Performance, 1(3), 288-299. What it reports: Participants rated the likelihood of possible outcomes of described events. Those told the true outcome judged it more probable than those not told, and asking them to disregard it did not remove the effect.

Fischhoff, B., & Beyth, R. (1975). I knew it would happen. Organizational Behavior and Human Performance, 13(1), 1-16. What it reports: Before a pair of state visits, people gave probabilities to possible outcomes and later recalled them. Outcomes that occurred were recalled as having been rated more likely, and outcomes that did not occur as less likely.

Key ideas

Hindsight Bias: Once you know how something turned out, you lose the ability to reconstruct what you believed before you knew.

Outcome Bias: Judging the quality of a decision by how it turned out rather than by whether the process behind it was sound.

The Illusion of Understanding: The past looks explicable because the mind builds a coherent story out of whatever material it happens to have, not because the material was sufficient.

The Illusion of Validity: The confidence people have in a judgment tracks the coherence of the story they can build from the evidence in front of them, not the actual predictive power of that evidence.

Availability Heuristic: Judging how common or plausible something is by how easily instances come to mind.

Denominator Neglect: Attending to the number of cases and ignoring the base they sit on.

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