HindsightBias

Hindsight bias, also known as the hindsight effect or the knew-it-all-along effect, is a cognitive bias in which people judge past events as having been more predictable than they actually were. After an event, individuals often perceive the outcome as inevitable or obvious, attributing more foresight to themselves or others than was available at the time.

Mechanisms: Hindsight bias stems from reconstructive memory, the post-event availability of information, and a desire to seem accurate. Knowing the result shifts interpretation of earlier data and can make people retroactively emphasize clues that support the outcome. It can be stronger with higher confidence or expertise and more information about the outcome being available afterward. It overlaps with, but is distinct from, confirmation bias and outcome bias.

Examples: In experiments, participants judge the likelihood of events after learning the outcome, rating them as more probable than before. In daily life, fans, investors, and policymakers often describe results as obviously inevitable once known, even though they were uncertain beforehand.

Implications and mitigation: Hindsight bias can hinder learning from mistakes and distort accountability. It may bias decision reviews and risk assessments. Mitigation strategies include recording initial probabilities, conducting pre-mortems, and considering alternative explanations to counter the post hoc narrative.

History: The term was coined by Baruch Fischhoff in the 1970s after studies showing people overestimate how predictable events were after they occur. It is a widely documented phenomenon in psychology and behavioral economics and has been demonstrated across cultures and domains.