The Hindsight Bias:

Often people will make certain claims or judgments about a situation after they
have seen it conclude. Once a series of events plays out and one is aware of the
outcome it is easy to exclaim: “oh yeah, I knew it all along.” It is a common
observation that events that took place in the past seem more conceivable and
more predictable than events that have not yet played themselves out.
In casual situations people often make judgments, attempting to foretell what they
see as the outcome of a given situation.  These predictions may be right or wrong
but it is common for people to recall their correct predictions and forget about the
faulty ones.  This attempt to gain credibility can confuse the speaker because it
gives them an erroneous conception of probability and of their own ability to predict
random events.

Many psychological models of memory impairment attempt to explain how this type
of cognitive error might stem from a few different causal factors. Psychologists
think that knowledge about the outcome of an event might alter or erase previous
memories related to the event before it played out.  This shows us how volatile and
delicate our memory really is.  Another possible causal factor for the hindsight bias
is related to cognitive distortion. Motivational factors and factors related to the
heuristics used in recalling events might make the original judgments less easy to
The idea of hindsight bias was pioneered by B. Fischhoff. His Immediate
Assimilation Hypothesis states that the memory for original predictions is altered
by the subsequent outcome of an event (Fischhoff, 1975).

Sporting events, for example, are often hotly debated. Sure enough, after the
outcome of a game, or a season there are many more people than is statistically
probable that claim to have predicted the outcome all along.

The dramatic fervor that fans display for their team is rekindled after a win but
quickly ended and forgotten about after a loss. Often when a situation is playing out
an individual might throw in a quiet remark about their prediction for a certain event.
If they lose, the remark is forgotten, if they win they can then speak vociferously
about their “uncanny” prediction.

The hindsight bias, much like many of the phenomena described by psychologists,
seems to many people to be “common sense.” This view is influenced by the
hindsight bias, the tendency to see things as obvious, but only after the fact.  
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