List of Cognitive Biases (Alphabetical)

The following list consists primarily of items reproduced by general permission from  This list also contains a few items named by Jack Pelham of SRBT, as well as certain notes added by SRBT.  Such notes appear interspersed in green font.  We have retained hyperlinks to Wikipedia articles and citations.  These links (in orange font) will redirect to Wikipedia and will open in a new tab.  You may see Wikipedia’s list here.  Biases that appear in green font below are items found in the literature but not on Wikipedia’s list.

NOTE: This list has nearly 100 entries, some of which are quite similar to each other and could rightly be grouped together into categories.  They are listed alphabetically here and by category on this page.

  1. Ambiguity effect – the tendency to avoid options for which missing information makes the probability seem “unknown.”[8]
  2. Anchoring or focalism – the tendency to rely too heavily, or “anchor,” on one trait or piece of information when making decisions.[9][10]
  3. Attentional bias – the tendency to pay attention to emotionally dominant stimuli in one’s environment and to neglect relevant data when making judgments of a correlation or association.[11][12]
  4. Availability heuristic – the tendency to overestimate the likelihood of events with greater “availability” in memory, which can be influenced by how recent the memories are or how unusual or emotionally charged they may be.[13]
  5. Availability cascade – a self-reinforcing process in which a collective belief gains more and more plausibility through its increasing repetition in public discourse (or “repeat something long enough and it will become true”).[14]
  6. Backfire effect – when people react to disconfirming evidence by strengthening their beliefs.[15]
  7. Bandwagon effect – the tendency to do (or believe) things because many other people do (or believe) the same. Related to groupthink and herd behavior.[16]
  8. Base rate fallacy or base rate neglect – In a sequence of probabilities, the tendency to ignore the first.[17]
  9. Belief bias – an effect where someone’s evaluation of the logical strength of an argument is biased by the believability of the conclusion.[18]
  10. Bias blind spot – the tendency to see oneself as less biased than other people, or to be able to identify more cognitive biases in others than in oneself.[19]SRBT notes that not all people are equally biased or influenced by their biases.  Indeed, one’s mind may suggest an inaccurate answer (stemming from a bias), but reject that answer as the result of acquired wisdom.
  11. Choice-supportive bias – the tendency to remember one’s choices (not options, but choices made) as better than they actually were.[20]
  12. Clustering illusion – the tendency to over-expect small runs, streaks, or clusters in large samples of random data (that is, seeing phantom patterns).[10]
  13. Confirmation bias – the tendency to search for, interpret and remember information in a way that confirms one’s preconceptions.[21]
  14. Congruence bias – the tendency to test hypotheses exclusively through direct testing, instead of testing possible alternative hypotheses.[10]
  15. Conjunction fallacy – the tendency to assume that specific conditions are more probable than general ones.[22]
  16. Conservatism or regressive bias – the tendency to underestimate high values and high likelihoods while overestimating low ones.[23][24][25]
  17. Conservatism (Bayesian) – the tendency to insufficiently revise one’s belief when presented with new evidence.[23][26][27]
  18. Contrast effect – the enhancement or reduction of a certain perception’s weight when compared with a recently observed, contrasting object.[28] This definition is well served with an example:  A certain piece of music is received more favorably when heard alone than when heard immediately after a piece that the listener disliked.  
  19. Curse of knowledge – when knowledge of a topic diminishes one’s ability to think about it from a less-informed (but more neutral) perspective.[29]
  20. Decoy effect – preferences change when there is a third option that is asymmetrically dominated
  21. Denomination effect – the tendency to spend more money when it is denominated in small amounts (e.g. coins) rather than large amounts (e.g. bills).[30]
  22. Devil effect – the tendency to discount positive aspects of a person, institution, or idea, based upon a generally negative assessment of the whole.  See it mentioned in the Wikipedia article on the Halo Effect here.
  23. Distinction bias – the tendency to view two options as more dissimilar when evaluating them simultaneously than when evaluating them separately.[31]
  24. Duration neglect – the neglect of the duration of an episode in determining its value
  25. Empathy gap – the tendency to underestimate the influence or strength of feelings, in either oneself or others.
  26. Endowment effect – the fact that people often demand much more to give up an object than they would be willing to pay to acquire it.[32]
  27. Essentialism – categorizing people and things according to their essential nature, in spite of variations.[33]
  28. Exaggerated expectation – based on the estimates, real-world evidence turns out to be less extreme than our expectations (conditionally inverse of the conservatism bias).[23][34]
  29. Experimenter’s or expectation bias – the tendency for experimenters to believe, certify, and publish data that agree 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.[35]
  30. False-consensus effect – the tendency of a person to overestimate how much other people agree with him or her.
  31. Functional fixedness – limits a person to using an object only in the way it is traditionally used.
  32. Focusing effect – the tendency to place too much importance on one aspect of an event.[36]
  33. Forer effect or Barnum effect – the observation that individuals will give high accuracy ratings to descriptions of their personality that supposedly are tailored specifically for them, but are in fact vague and general enough to apply to a wide range of people. This effect can provide a partial explanation for the widespread acceptance of some beliefs and practices, such as astrology, fortune telling, graphology, and some types of personality tests.
  34. Framing effect – drawing different conclusions from the same information, depending on how or by whom that information is presented.
  35. Frequency illusion – the illusion in which a word, a name or other thing that has recently come to one’s attention suddenly seems to appear with improbable frequency shortly afterwards. Also known as Baader-Meinhof phenomenon. (see also recency illusion).[37]
  36. Gambler’s fallacy – the tendency to think that future probabilities are altered by past events, when in reality they are unchanged. Results from an erroneous conceptualization of the law of large numbers. For example, “I’ve flipped heads with this coin five times consecutively, so the chance of tails coming out on the sixth flip is much greater than heads.”
  37. Halo effect – the tendency to discount the flaws or errors of an admired person, institution, or idea.  See Wikipedia article here.
  38. Hard-easy effect – Based on a specific level of task difficulty, the confidence in judgments is too conservative and not extreme enough[23][38][39][40]
  39. Hindsight bias – sometimes called the “I-knew-it-all-along” effect, the tendency to see past events as being predictable[41] at the time those events happened.
  40. Hostile media effect – the tendency to see a media report as being biased, owing to one’s own strong partisan views.  SRBT notes that some media reports may indeed be biased and partisan.  The point here, therefore, should be that some consumers tend to discount specific assertions of fact as “biased” based upon the general bias of the media outlet in question.
  41. Hot-hand fallacy – The “hot-hand fallacy” (also known as the “hot hand phenomenon” or “hot hand”) is the fallacious belief that a person who has experienced success has a greater chance of further success in additional attempts
  42. Hyperbolic discounting – the tendency for people to have a stronger preference for more immediate payoffs relative to later payoffs, where the tendency increases the closer to the present both payoffs are.[42] Also known as current moment bias, present-bias, and related to Dynamic inconsistency.
  43. Identifiable victim effect – the tendency to respond more strongly to a single identified person at risk than to a large group of people at risk.[43]
  44. Illusion of control – the tendency to overestimate one’s degree of influence over other external events.[44]
  45. Illusion of validity – belief that furtherly acquired information generates additional relevant data for predictions, even when it evidently does not.[45]
  46. Illusory correlation – inaccurately perceiving a relationship between two unrelated events.[46][47]
  47. Impact bias – the tendency to overestimate the length or the intensity of the impact of future feeling states.[48]
  48. Information bias – the tendency to seek information even when it cannot affect action.[49]
  49. Interpretation blindness – the state in which a person is dogmatic about the meaning of a text (generally, such as the Constitution, the Quran, the Bible, etc.) while forgetting that his or her understanding of that text is the result of the process of interpretation.  The likelihood of misinterpretation is assumed to be zero, so the interpretation replaces as a concrete any further reflection upon the intended meaning of the text.  (Bias named by Jack Pelham.)
  50. Irrational escalation – the phenomenon where people justify increased investment in a decision, based on the cumulative prior investment, despite new evidence suggesting that the decision was probably wrong.  SRBT notes that this is also called the Sunk Cost Effect.
  51. Just-world hypothesis – the tendency for people to want to believe that the world is fundamentally just, causing them to rationalize an otherwise inexplicable injustice as deserved by the victim(s).
  52. Less-is-better effect – a preference reversal where a dominated smaller set is preferred to a larger set.
  53. Loss aversion – “the disutility of giving up an object is greater than the utility associated with acquiring it”.[50] (see also Sunk cost effects and endowment effect).
  54. Ludic fallacy – the misuse of games to model real-life situations.  SRBT notes that Wikipedia’s further description is helpful:  “basing studies of chance on the narrow world of games and dice.”
  55. Mere exposure effect – the tendency to express undue liking for things merely because of familiarity with them.[51]
  56. Money illusion – the tendency to concentrate on the nominal (face value) of (fiat) money rather than its value in terms of purchasing power.[52]
  57. Moral credential effect – the tendency of a track record of non-prejudice to increase subsequent prejudice.
  58. Negativity bias – psychological phenomenon by which humans have a greater recall of unpleasant memories compared with positive memories.[53]
  59. Neglect of probability – the tendency to completely disregard probability when making a decision under uncertainty.[54]
  60. Normalcy bias – the refusal to plan for, or react to, a disaster which has never happened before.
  61. 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.
  62. Observer-expectancy effect – when a researcher expects a given result and therefore unconsciously manipulates an experiment or misinterprets data in order to find it (see also subject-expectancy effect).
  63. Omission bias – the tendency to judge harmful actions as worse, or less moral, than equally harmful omissions (inactions).[55]
  64. Optimism bias – the tendency to be over-optimistic, overestimating favorable and pleasing outcomes (see also wishful thinking, valence effect, positive outcome bias).[56][57]
  65. Ostrich effect – ignoring an obvious (negative) situation.
  66. 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.
  67. Overconfidence effect – 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.[23][58][59][60]
  68. Pareidolia – a vague and random stimulus (often an image or sound) is perceived as significant, e.g., seeing images of animals or faces in clouds, the man in the moon, and hearing non-existent hidden messages on records played in reverse.
  69. Pessimism bias – the tendency for some people, especially those suffering from depression, to overestimate the likelihood of negative things happening to them.
  70. Planning fallacy – the tendency to underestimate task-completion times.[48]
  71. Post-purchase rationalization – the tendency to persuade oneself through rational argument that a purchase was a good value.
  72. Programmer’s bias – the tendency of a programmer to assume that a complicated program he has written will be easily navigated by users since he himself can navigate it easily.  (Bias named by Jack Pelham.)
  73. Pro-innovation bias – the tendency to reflect an excessive optimism towards an invention/innovation’s usefulness throughout society, while often failing to identify limitations and weaknesses or address the possibility of failure.
  74. Pseudocertainty effect – the tendency to make risk-averse choices if the expected outcome is positive, but make risk-seeking choices to avoid negative outcomes.[61]
  75. Reactance – the urge to do the opposite of what someone wants you to do out of a need to resist a perceived attempt to constrain your freedom of choice (see also Reverse psychology).
  76. Reactive devaluation – devaluing proposals that are purportedly originated with an adversary.
  77. Recency bias – a cognitive bias that results from disproportionate salience attributed to recent stimuli or observations – the tendency to weigh recent events more than earlier events (see also peak-end rule, recency effect).
  78. Recency illusion – the illusion that a word or language usage is a recent innovation when it is in fact long-established (see also frequency illusion).
  79. Restraint bias – the tendency to overestimate one’s ability to show restraint in the face of temptation.
  80. Rhyme as reason effect – rhyming statements are perceived as more truthful. A famous example being used in the O.J Simpson trial with the defense’s use of the phrase “If the gloves don’t fit, then you must acquit.”  SRBT notes that the actual quotation was “If it doesn’t fit, you must acquit.”
  81. Risk compensation / Peltzman effect – the tendency to take greater risks when perceived safety increases.
  82. Selective perception – the tendency for expectations to affect perception.
  83. Semmelweis reflex – the tendency to reject new evidence that contradicts a paradigm.[27]
  84. Selection bias – the distortion of a statistical analysis, resulting from the method of collecting samples. If the selection bias is not taken into account then certain conclusions drawn may be wrong.
  85. Social comparison bias – the tendency, when making hiring decisions, to favour potential candidates who don’t compete with one’s own particular strengths.[62]
  86. Social desirability bias – the tendency to over-report socially desirable characteristics or behaviours and under-report socially undesirable characteristics or behaviours.[63]
  87. Status quo bias – the tendency to like things to stay relatively the same (see also loss aversion, endowment effect, and system justification).[64][65]
  88. Stereotyping – expecting a member of a group to have certain characteristics without having actual information about that individual.
  89. Subadditivity effect – the tendency to estimate that the likelihood of an event is less than the sum of its (more than two) mutually exclusive components.[66]
  90. Subjective validation – perception that something is true if a subject’s belief demands it to be true. Also assigns perceived connections between coincidences.
  91. Survivorship bias – concentrating on the people or things that “survived” some process and inadvertently overlooking those that didn’t because of their lack of visibility.
  92. Time-saving bias – underestimations of the time that could be saved (or lost) when increasing (or decreasing) from a relatively low speed and overestimations of the time that could be saved (or lost) when increasing (or decreasing) from a relatively high speed.
  93. Unit bias – the tendency to want to finish a given unit of a task or an item. Strong effects on the consumption of food in particular.[67]
  94. Well travelled road effect – underestimation of the duration taken to traverse oft-traveled routes and overestimation of the duration taken to traverse less familiar routes.
  95. Zero-risk bias – preference for reducing a small risk to zero over a greater reduction in a larger risk.
  96. Zero-sum heuristic – intuitively judging a situation to be zero-sum (i.e., that gains and losses are correlated). Derives from the zero-sum game in game theory, where wins and losses sum to zero.[68][69] The frequency with which this bias occurs may be related to the social dominance orientation personality factor.