Cognitive Biases

Cognitive Biases

A remarkably large number of cognitive biases has been identified.  Following is a partial list of cognitive biases.  More complete compilations of cognitive biases are given in the references below.

Perception Biases:

  • Selective perception: The tendency for expectations to affect perception.
  • Confirmation bias: the tendency to search for, interpret, focus on, and remember information in a way that confirms one’s preconceptions.
  • Observation selection bias: the effect of suddenly noticing things that were not noticed previously – and as a result wrongly assuming that the frequency has increased.
  • Contrast effect: the enhancement or reduction of a certain perception’s stimuli when compared with a recently observed, contrasting object.
  • Illusory correlation: perceiving a relationship between two unrelated events.

Reasoning Biases:

  • Anchoring: the tendency to rely too heavily, or anchor, on one piece of information when making decisions.
  • Belief bias: the tendency to bias one’s evaluation of the logical strength of an argument based on the believability of the conclusion.
  • Conservatism (Bayesian): the tendency to insufficiently revise one’s belief when presented with new evidence.
  • Framing effect: The tendency to draw different conclusions from the same information, depending on how or by whom that information is presented.
  • Subjective validation: the tendency to perceive that something is true if one’s beliefs demand it to be true.
  • Illusion of validity: the belief that further acquired information generates additional relevant data for predictions, even when it evidently does not.
  • Sunk cost fallacy: the tendency to justify increased investment in a decision, based on the cumulative prior investment, despite new evidence suggesting that the decision was probably wrong.
  • Backfire effect: the tendency to react to disconfirming evidence by strengthening one’s beliefs.
  • Overconfidence effect: the tendency to have excessive confidence in one’s own answers to questions. For example, for certain types of questions, answers that people rate as “99% certain” turn out to be wrong 40% of the time.
  • Survivorship bias: the tendency to concentrate on the people or things that “survived” some process and overlooking those that didn’t because of their lack of visibility.
  • Localism: the tendency to focus on things that are near in space and time, rather than more consequential matters that are more distant.

Scientific/Technical Biases:

  • Observer expectancy effect: when a researcher expects a given result and therefore unconsciously manipulates an experiment or misinterprets data in order to find it.
  • Congruence bias: the tendency to check hypotheses exclusively through direct testing, instead of considering possible alternative hypotheses.
  • Expectation bias: the tendency for experimenters to believe, certify, and publish data that agrees with their expectations for the outcome of an experiment and to disbelieve, discard, or downgrade the corresponding weightings for data that appear to conflict with those expectations.
  • Clustering illusion: the tendency to see phantom runs or clusters in large samples of random data.
  • Insensitivity to sample size: the tendency to under-expect variation in small samples.
  • Semmelweiss reflex: the tendency to reject new evidence that contradicts a paradigm.
  • Pro-innovation bias: the tendency to have an excessive optimism towards an invention or innovation’s usefulness throughout society, while often failing to identify its limitations and weaknesses.

Probability and Likelihood Biases:

  • Availability heuristic: the tendency to over-estimate the likelihood of events with greater “availability” in memory (recency, unusual, emotionally charged, etc.).
  • Neglect of probability: the tendency to completely disregard probability when making a decision under uncertainty.
  • Gambler’s fallacy: the tendency to think that future probabilities for random events are altered by past events, when in reality they are unchanged. The gambler mistakenly believes that if something occurs more frequently than normal during some period, it will occur less frequently in the future.  Alternatively, if something occurs less frequently than normal during some period, it will occur more frequently in the future.
  • Hot hand fallacy: the belief that a person who has experienced success has a greater chance of further success in additional attempts.
  • Subadditivity effect: the tendency to judge probability of the whole to be less than the probabilities of the parts.
  • Conservatism bias: the tendency to overestimate high values and high likelihoods while low values and low likelihoods are underestimated.
  • Optimism bias: the tendency to be over-optimistic, overestimating the likelihood of favorable and pleasing outcomes.
  • Pessimism bias: The tendency for some people to overestimate the likelihood of negative things happening.

Group-Thought Biases:

  • Bandwagon effect: the tendency to do or believe things because many other people do or believe the same. Related to groupthink and herd behavior.
  • Availability cascade: repetition of a collective belief in public discourse so it becomes more and more plausible.

Moral Reasoning Biases:

  • Just world hypothesis: The tendency to want to believe that the world is fundamentally just, causing the rationalization of an otherwise inexplicable injustice as being deserved by the victim(s).
  • Omission bias: the tendency to judge harmful actions as worse, or less moral, than equally harmful omissions (inactions).
  • Stereotyping: expecting a member of a group to have certain characteristics without having actual information about that individual.

Loss/Risk Biases:

  • Loss aversion: the tendency to view the disutility of giving up an object as greater than the utility associated with acquiring it.
  • Zero-risk bias: the tendency to prefer reducing a small risk to zero over a greater reduction in a larger risk.
  • Risk compensation: the tendency to take greater risks when perceived safety increases.

Post Hoc Biases:

  • Hindsight bias: the tendency to see past events as being predictable at the time those events happened.
  • Choice-supportive bias: the tendency to remember one’s choices as better than they actually were.
  • Outcome bias: the tendency to judge a decision by its eventual outcome instead of based on the quality of the decision at the time it was made.

Planning/Preparation Biases:

  • Planning fallacy: The tendency to underestimate task-completion times.
  • Normalcy bias: the tendency to refuse to prepare for, or react to, a disaster which has never happened before.

Other Personal Biases:

  • Status quo bias: the tendency to prefer things to stay relatively the same.
  • Bias blind spot: the tendency to be able to identify more cognitive bias in other people than in oneself.
  • Illusion of control: the tendency to overestimate one’s degree of influence over other external events.
  • Functional fixedness: the tendency to use an object only in the way it is traditionally used.
  • Reactive devaluation: devaluing proposals only because they are purportedly originated with an adversary.

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