Hindsight bias, sometimes called the I-knew-it-all-along effect, is the inclination to see past events as being predictable and reasonable to expect, perhaps because they are more available than possible outcomes which did not occur. Subjects also tend to remember their own future predictions as being more accurate than they were after the fact. People are, in effect, biased by the knowledge of what has actually happened when evaluating its likelihood.

Hindsight bias has been demonstrated experimentally in a variety of settings, including politics, games and medicine.

One example of hindsight bias may be the patency of the connection between US support of the mujahadeen during the Soviet invasion of Afghanistan and the September 11, 2001 Terrorist Attacks.

It has been shown that examining possible alternatives may reduce the effects of this bias.

See also: cognitive bias, historian's fallacy, list of cognitive biases.

References

• Fischhoff, B. & Beyth, R. (1975). "I knew it would happen": Remembered probabilities of once-future things. Organizational Behavior and Human Performance 13, 1-16.