List of cognitive biases
es are systematic patterns of deviation from norm and/or rationality in judgment. They are often studied in psychology and behavioral economics.
Although the reality of most of these biases is confirmed by reproducible research, there are often controversies about how to classify these biases or how to explain them. Gerd Gigerenzer has criticized the framing of cognitive biases as errors in judgment, and favors interpreting them as arising from rational deviations from logical thought.
Explanations include information-processing rules, called heuristics, that the brain uses to produce decisions or judgments. Biases have a variety of forms and appear as cognitive bias, such as mental noise, or motivational bias, such as when beliefs are distorted by wishful thinking. Both effects can be present at the same time.
There are also controversies over some of these biases as to whether they count as useless or irrational, or whether they result in useful attitudes or behavior. For example, when getting to know others, people tend to ask leading questions which seem biased towards confirming their assumptions about the person. However, this kind of confirmation bias has also been argued to be an example of social skill; a way to establish a connection with the other person.
Although this research overwhelmingly involves human subjects, some findings that demonstrate bias have been found in non-human animals as well. For example, loss aversion has been shown in monkeys and hyperbolic discounting has been observed in rats, pigeons, and monkeys.
Belief, Decision-making and behavioral biases
These biases affect belief formation, reasoning processes, business and economic decisions, and human behavior in general.| Name | Type | Description |
| Agent detection | False priors | The inclination to presume the purposeful intervention of a sentient or intelligent agent. |
| Ambiguity effect | Prospect theory | The tendency to avoid options for which the probability of a favorable outcome is unknown. |
| Anchoring or focalism | Anchoring bias | The tendency to rely too heavily, or "anchor", on one trait or piece of information when making decisions. |
| Anthropocentric thinking | Availability bias | The tendency to use human analogies as a basis for reasoning about other, less familiar, biological phenomena. |
| Anthropomorphism or personification | Availability bias | The tendency to characterize animals, objects, and abstract concepts as possessing human-like traits, emotions, and intentions. The opposite bias, of not attributing feelings or thoughts to another person, is dehumanised perception, a type of objectification. |
| Attentional bias | Availability bias | The tendency of perception to be affected by recurring thoughts. |
| Attribute substitution | Occurs when a judgment has to be made that is computationally complex, and instead a more easily calculated heuristic attribute is substituted. This substitution is thought of as taking place in the automatic intuitive judgment system, rather than the more self-aware reflective system. | |
| Automation bias | False priors | The tendency to depend excessively on automated systems which can lead to erroneous automated information overriding correct decisions. |
| Availability heuristic | Availability bias | 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. |
| Backfire effect | Confirmation bias | The reaction to disconfirming evidence by strengthening one's previous beliefs. Note: the existence of this bias as a widespread phenomenon has been disputed in empirical studies |
| Base rate fallacy or Base rate neglect | Extension neglect | The tendency to ignore general information and focus on information only pertaining to the specific case, even when the general information is more important. |
| Belief bias | Truthiness | An effect where someone's evaluation of the logical strength of an argument is biased by the believability of the conclusion. |
| Berkson's paradox | Logical fallacy | The tendency to misinterpret statistical experiments involving conditional probabilities. |
| Clustering illusion | Apophenia | The tendency to overestimate the importance of small runs, streaks, or clusters in large samples of random data. |
| Compassion fade | Extension neglect | The predisposition to behave more compassionately towards a small number of identifiable victims than to a large number of anonymous ones. |
| Confirmation bias | Confirmation bias | The tendency to search for, interpret, focus on and remember information in a way that confirms one's preconceptions. |
| Congruence bias | Confirmation bias | The tendency to test hypotheses exclusively through direct testing, instead of testing possible alternative hypotheses. |
| Conjunction fallacy | Extension neglect | The tendency to assume that specific conditions are more probable than a more general version of those same conditions. For example, subjects in one experiment perceived the probability of a woman being both a bank teller and a feminist as more likely than the probability of her being a bank teller. |
| Conservatism bias | Anchoring bias | The tendency to revise one's belief insufficiently when presented with new evidence. |
| Continued influence effect | Confirmation bias | The tendency to believe previously learned misinformation even after it has been corrected. Misinformation can still influence inferences one generates after a correction has occurred. cf. Backfire effect |
| Contrast effect | Framing effect | The enhancement or reduction of a certain stimulus' perception when compared with a recently observed, contrasting object. |
| Curse of knowledge | When better-informed people find it extremely difficult to think about problems from the perspective of lesser-informed people. | |
| Declinism | The predisposition to view the past favorably and future negatively. | |
| Decoy effect | Framing effect | Preferences for either option A or B change in favor of option B when option C is presented, which is completely dominated by option B and partially dominated by option A. |
| Default effect | Framing effect | When given a choice between several options, the tendency to favor the default one. |
| Denomination effect | Framing effect | The tendency to spend more money when it is denominated in small amounts rather than large amounts. |
| Disposition effect | Prospect theory | The tendency to sell an asset that has accumulated in value and resist selling an asset that has declined in value. |
| Distinction bias | Framing effect | The tendency to view two options as more dissimilar when evaluating them simultaneously than when evaluating them separately. |
| Dread aversion | Prospect theory | Just as losses yield double the emotional impact of gains, dread yields double the emotional impact of savouring. |
| Dunning–Kruger effect | The tendency for unskilled individuals to overestimate their own ability and the tendency for experts to underestimate their own ability. | |
| Duration neglect | Extension neglect | The neglect of the duration of an episode in determining its value. |
| Empathy gap | The tendency to underestimate the influence or strength of feelings, in either oneself or others. | |
| End-of-history illusion | The age-independent belief that one will change less in the future than one has in the past. | |
| Endowment effect | Prospect theory | The tendency for people to demand much more to give up an object than they would be willing to pay to acquire it. |
| The tendency to expect or predict more extreme outcomes than those outcomes that actually happen. | ||
| Experimenter's or expectation bias | Confirmation 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. |
| Forer effect or Barnum effect | Egocentric bias | 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. |
| Form function attribution bias | In human–robot interaction, the tendency of people to make systematic errors when interacting with a robot. People may base their expectations and perceptions of a robot on its appearance and attribute functions which do not necessarily mirror the true functions of the robot. | |
| Framing effect | Framing effect | Drawing different conclusions from the same information, depending on how that information is presented. |
| Frequency illusion or Baader–Meinhof phenomenon | Availability bias | The frequency illusion is that once something has been noticed then every instance of that thing is noticed, leading to the belief it has a high frequency of occurrence. The Baader–Meinhof phenomenon is the illusion where something that has recently come to one's attention suddenly seems to appear with improbable frequency shortly afterwards. The Baader–Meinhof phenomenon is sometimes conflated with frequency illusion and the recency illusion. It was named after an incidence of frequency illusion in which the Baader–Meinhof Group was mentioned. |
| Functional fixedness | Anchoring bias | Limits a person to using an object only in the way it is traditionally used. |
| Gambler's fallacy | Logical fallacy | The tendency to think that future probabilities are altered by past events, when in reality they are unchanged. The fallacy arises 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." |
| Gender bias | False priors | A widely held set of implicit biases that discriminate against a gender. For example, the assumption that women are less suited to jobs requiring high intellectual ability. Or the assumption that people or animals are male in the absence of any indicators of gender. |
| Hard–easy effect | The tendency to overestimate one's ability to accomplish hard tasks, and underestimate one's ability to accomplish easy tasks | |
| Hindsight bias | Sometimes called the "I-knew-it-all-along" effect, the tendency to see past events as being predictable at the time those events happened. | |
| Hot-hand fallacy | Logical fallacy | The "hot-hand fallacy" is the belief that a person who has experienced success with a random event has a greater chance of further success in additional attempts. |
| Hyperbolic discounting | Extension neglect | Discounting is the tendency for people to have a stronger preference for more immediate payoffs relative to later payoffs. Hyperbolic discounting leads to choices that are inconsistent over time – people make choices today that their future selves would prefer not to have made, despite using the same reasoning. Also known as current moment bias, present-bias, and related to Dynamic inconsistency. A good example of this: a study showed that when making food choices for the coming week, 74% of participants chose fruit, whereas when the food choice was for the current day, 70% chose chocolate. |
| IKEA effect | The tendency for people to place a disproportionately high value on objects that they partially assembled themselves, such as furniture from IKEA, regardless of the quality of the end product. | |
| Illicit transference | Logical fallacy | Occurs when a term in the distributive and collective sense are treated as equivalent. The two variants of this fallacy are the fallacy of composition and the fallacy of division. |
| Illusion of control | Egocentric bias | The tendency to overestimate one's degree of influence over other external events. |
| Illusion of validity | Egocentric bias | Believing that one's judgments are accurate, especially when available information is consistent or inter-correlated. |
| Illusory correlation | Apophenia | Inaccurately perceiving a relationship between two unrelated events. |
| Illusory truth effect | Truthiness | A tendency to believe that a statement is true if it is easier to process, or if it has been stated multiple times, regardless of its actual veracity. These are specific cases of truthiness. |
| Impact bias | The tendency to overestimate the length or the intensity of the impact of future feeling states. | |
| Implicit association | Availability bias | The speed with which people can match words depends on how closely they are associated. |
| Information bias | The tendency to seek information even when it cannot affect action. | |
| Insensitivity to sample size | Extension neglect | The tendency to under-expect variation in small samples. |
| Interoceptive bias | The tendency for sensory input about the body itself to affect one's judgement about external, unrelated circumstances. | |
| Irrational escalation or Escalation of commitment | Logical fallacy | 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. Also known as the sunk cost fallacy. |
| Law of the instrument | Anchoring bias | An over-reliance on a familiar tool or methods, ignoring or under-valuing alternative approaches. "If all you have is a hammer, everything looks like a nail." |
| Less-is-better effect | Extension neglect | The tendency to prefer a smaller set to a larger set judged separately, but not jointly. |
| Loss aversion | Prospect theory | The perceived disutility of giving up an object is greater than the utility associated with acquiring it.. |
| Mere exposure effect | Familiarity principle | The tendency to express undue liking for things merely because of familiarity with them. |
| Money illusion | The tendency to concentrate on the nominal value of money rather than its value in terms of purchasing power. | |
| Moral credential effect | Occurs when someone who does something good gives themselves permission to be less good in the future. | |
| Neglect of probability | Extension neglect | The tendency to completely disregard probability when making a decision under uncertainty. |
| Non-adaptive choice switching | After experiencing a bad outcome with a decision problem, the tendency to avoid the choice previously made when faced with the same decision problem again, even though the choice was optimal. Also known as "once bitten, twice shy" or "hot stove effect". | |
| Normalcy bias | Cognitive dissonance | The refusal to plan for, or react to, a disaster which has never happened before. |
| Observer-expectancy effect | Confirmation bias | When a researcher expects a given result and therefore unconsciously manipulates an experiment or misinterprets data in order to find it. |
| Omission bias | The tendency to judge harmful actions as worse, or less moral, than equally harmful inactions. | |
| Optimism bias | The tendency to be over-optimistic, underestimating greatly the probability of undesirable outcomes and overestimating favorable and pleasing outcomes. | |
| Ostrich effect | Ignoring an obvious situation. | |
| 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. | |
| Overconfidence effect | Egocentric bias | 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. |
| Pareidolia | Apophenia | A vague and random stimulus 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. |
| Pessimism bias | The tendency for some people, especially those suffering from depression, to overestimate the likelihood of negative things happening to them. | |
| Plan continuation bias | Logical fallacy | Failure to recognize that the original plan of action is no longer appropriate for a changing situation or for a situation that is different than anticipated. |
| Planning fallacy | Egocentric bias | The tendency to underestimate one's own task-completion times. |
| Present bias | The tendency of people to give stronger weight to payoffs that are closer to the present time when considering trade-offs between two future moments. | |
| Plant blindness | The tendency to ignore plants in their environment and a failure to recognize and appreciate the utility of plants to life on earth. | |
| 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. | |
| Projection bias | The tendency to overestimate how much our future selves share one's current preferences, thoughts and values, thus leading to sub-optimal choices. | |
| Proportionality Bias | Our innate tendency to assume that big events have big causes, may also explain our tendency to accept conspiracies. | |
| Pseudocertainty effect | Prospect theory | The tendency to make risk-averse choices if the expected outcome is positive, but make risk-seeking choices to avoid negative outcomes. |
| Recency illusion | The illusion that a phenomenon one has noticed only recently is itself recent. Often used to refer to linguistic phenomena; the illusion that a word or language usage that one has noticed only recently is an innovation when it is in fact long-established. | |
| Systematic Bias | Judgement that arises when targets of differentiating judgement become subject to effects of regression that are not equivalent. | |
| Restraint bias | Egocentric bias | The tendency to overestimate one's ability to show restraint in the face of temptation. |
| Rhyme as reason effect | Truthiness | 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." |
| Risk compensation / Peltzman effect | The tendency to take greater risks when perceived safety increases. | |
| Salience bias | Availability bias | The tendency to focus on items that are more prominent or emotionally striking and ignore those that are unremarkable, even though this difference is often irrelevant by objective standards. |
| Scope neglect or scope insensitivity | Extension neglect | The tendency to be insensitive to the size of a problem when evaluating it. For example, being willing to pay as much to save 2,000 children or 20,000 children |
| Selection bias | Availability bias | The tendency to notice something more when something causes us to be more aware of it, such as when we buy a car, we tend to notice similar cars more often than we did before. They are not suddenly more common – we just are noticing them more. Also called the Observational Selection Bias. |
| Selective perception | Confirmation bias | The tendency for expectations to affect perception. |
| Semmelweis reflex | Confirmation bias | The tendency to reject new evidence that contradicts a paradigm. |
| Status quo bias | Prospect theory | The tendency to like things to stay relatively the same. |
| Stereotyping | False priors | Expecting a member of a group to have certain characteristics without having actual information about that individual. |
| Subadditivity effect | Logical fallacy | The tendency to judge probability of the whole to be less than the probabilities of the parts. |
| Subjective validation | Truthiness | Perception that something is true if a subject's belief demands it to be true. Also assigns perceived connections between coincidences. |
| Surrogation | Losing sight of the strategic construct that a measure is intended to represent, and subsequently acting as though the measure is the construct of interest. | |
| Survivorship bias | Availability bias | Concentrating on the people or things that "survived" some process and inadvertently overlooking those that didn't because of their lack of visibility. |
| System justification | Prospect theory | The tendency to defend and bolster the status quo. Existing social, economic, and political arrangements tend to be preferred, and alternatives disparaged, sometimes even at the expense of individual and collective self-interest. |
| Time-saving bias | Logical fallacy | Underestimations of the time that could be saved when increasing from a relatively low speed and overestimations of the time that could be saved when increasing from a relatively high speed. |
| Parkinson's law of triviality | The tendency to give disproportionate weight to trivial issues. Also known as bikeshedding, this bias explains why an organization may avoid specialized or complex subjects, such as the design of a nuclear reactor, and instead focus on something easy to grasp or rewarding to the average participant, such as the design of an adjacent bike shed. | |
| The standard suggested amount of consumption is perceived to be appropriate, and a person would consume it all even if it is too much for this particular person. | ||
| Weber–Fechner law | Difficulty in comparing small differences in large quantities. | |
| Well travelled road effect | Availability bias | Underestimation of the duration taken to traverse oft-traveled routes and overestimation of the duration taken to traverse less familiar routes. |
| Women are wonderful effect | A tendency to associate more positive attributes with women than with men. | |
| Zero-risk bias | Extension neglect | Preference for reducing a small risk to zero over a greater reduction in a larger risk. |
| Zero-sum bias | Logical fallacy | A bias whereby a situation is incorrectly perceived to be like a zero-sum game. |
Social biases
Memory errors and biases
In psychology and cognitive science, a memory bias is a cognitive bias that either enhances or impairs the recall of a memory, or that alters the content of a reported memory. There are many types of memory bias, including:| Name | Description |
| Bizarreness effect | Bizarre material is better remembered than common material. |
| Choice-supportive bias | The tendency to remember one's choices as better than they actually were. |
| or Regressive bias | Tendency to remember high values and high likelihoods/probabilities/frequencies as lower than they actually were and low ones as higher than they actually were. Based on the evidence, memories are not extreme enough. |
| Incorrectly remembering one's past attitudes and behaviour as resembling present attitudes and behaviour. | |
| Context effect | That cognition and memory are dependent on context, such that out-of-context memories are more difficult to retrieve than in-context memories. |
| Cross-race effect | The tendency for people of one race to have difficulty identifying members of a race other than their own. |
| Cryptomnesia | A form of misattribution where a memory is mistaken for imagination, because there is no subjective experience of it being a memory. |
| Egocentric bias | Recalling the past in a self-serving manner, e.g., remembering one's exam grades as being better than they were, or remembering a caught fish as bigger than it really was. |
| Fading affect bias | A bias in which the emotion associated with unpleasant memories fades more quickly than the emotion associated with positive events. |
| False memory | A form of misattribution where imagination is mistaken for a memory. |
| Generation effect | That self-generated information is remembered best. For instance, people are better able to recall memories of statements that they have generated than similar statements generated by others. |
| Google effect | The tendency to forget information that can be found readily online by using Internet search engines. |
| That humorous items are more easily remembered than non-humorous ones, which might be explained by the distinctiveness of humor, the increased cognitive processing time to understand the humor, or the emotional arousal caused by the humor. | |
| Lag effect | The phenomenon whereby learning is greater when studying is spread out over time, as opposed to studying the same amount of time in a single session. See also spacing effect. |
| Leveling and sharpening | Memory distortions introduced by the loss of details in a recollection over time, often concurrent with sharpening or selective recollection of certain details that take on exaggerated significance in relation to the details or aspects of the experience lost through leveling. Both biases may be reinforced over time, and by repeated recollection or re-telling of a memory. |
| Levels-of-processing effect | That different methods of encoding information into memory have different levels of effectiveness. |
| A smaller percentage of items are remembered in a longer list, but as the length of the list increases, the absolute number of items remembered increases as well. For example, consider a list of 30 items and a list of 100 items. An individual may remember 15 items from L30, or 50%, whereas the individual may remember 40 items from L100, or 40%. Although the percent of L30 items remembered is greater than the percent of L100, more L100 items are remembered than L30 items. | |
| Misinformation effect | Memory becoming less accurate because of interference from post-event information. |
| Modality effect | That memory recall is higher for the last items of a list when the list items were received via speech than when they were received through writing. |
| Mood-congruent memory bias | The improved recall of information congruent with one's current mood. |
| Negativity bias or Negativity effect | Psychological phenomenon by which humans have a greater recall of unpleasant memories compared with positive memories.. |
| Next-in-line effect | When taking turns speaking in a group using a predetermined order people tend to have diminished recall for the words of the person who spoke immediately before them. |
| Part-list cueing effect | That being shown some items from a list and later retrieving one item causes it to become harder to retrieve the other items. |
| Peak-end rule | That people seem to perceive not the sum of an experience but the average of how it was at its peak and how it ended. |
| Picture superiority effect | The notion that concepts that are learned by viewing pictures are more easily and frequently recalled than are concepts that are learned by viewing their written word form counterparts. |
| Positivity effect | That older adults favor positive over negative information in their memories. |
| Serial position effect | That items near the end of a sequence are the easiest to recall, followed by the items at the beginning of a sequence; items in the middle are the least likely to be remembered. |
| That information that takes longer to read and is thought about more is more easily remembered. | |
| Reminiscence bump | The recalling of more personal events from adolescence and early adulthood than personal events from other lifetime periods. |
| Self-relevance effect | That memories relating to the self are better recalled than similar information relating to others. |
| Source confusion | Confusing episodic memories with other information, creating distorted memories. |
| Spacing effect | That information is better recalled if exposure to it is repeated over a long span of time rather than a short one. |
| Spotlight effect | The tendency to overestimate the amount that other people notice your appearance or behavior. |
| Memory distorted towards stereotypes. | |
| Diminishment of the recency effect because a sound item is appended to the list that the subject is not required to recall. | |
| Suggestibility | A form of misattribution where ideas suggested by a questioner are mistaken for memory. |
| Tachypsychia | When time perceived by the individual either lengthens, making events appear to slow down, or contracts. |
| Telescoping effect | The tendency to displace recent events backward in time and remote events forward in time, so that recent events appear more remote, and remote events, more recent. |
| Testing effect | The fact that you more easily remember information you have read by rewriting it instead of rereading it. |
| Tip of the tongue phenomenon | When a subject is able to recall parts of an item, or related information, but is frustratingly unable to recall the whole item. This is thought to be an instance of "blocking" where multiple similar memories are being recalled and interfere with each other. |
| Overestimating the significance of the present. It is related to chronological snobbery with possibly an appeal to novelty logical fallacy being part of the bias. | |
| That the "gist" of what someone has said is better remembered than the verbatim wording. This is because memories are representations, not exact copies. | |
| von Restorff effect | That an item that sticks out is more likely to be remembered than other items. |
| Zeigarnik effect | That uncompleted or interrupted tasks are remembered better than completed ones. |