Cognitive Bias in Reasoning

Decision-making and behavioral biases

Many of these biases are studied for how they affect belief formation, business decisions, and scientific research.

• Bandwagon effect — the tendency to do (or believe) things because many other people do (or believe) the same. Related togroupthink and herd behaviour.
• Base rate fallacy — ignoring available statistical data in favor of particulars.
• Bias blind spot — the tendency not to compensate for one’s own cognitive biases.
• Choice-supportive bias — the tendency to remember one’s choices as better than they actually were.
• Confirmation bias — the tendency to search for or interpret information in a way that confirms one’s preconceptions.
• Congruence bias — the tendency to test hypotheses exclusively through direct testing, in contrast to tests of possible alternative hypotheses.
• Conservatism bias — the tendency to ignore the consequence of new evidence. (Related to base rate fallacy.)^[1]
• Contrast effect — the enhancement or diminishing of a weight or other measurement when compared with a recently observed contrasting object.
• Déformation professionnelle — the tendency to look at things according to the conventions of one’s own profession, forgetting any broader point of view.
• Distinction bias — the tendency to view two options as more dissimilar when evaluating them simultaneously than when evaluating them separately.^[2]
• 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”.^[3]
• Experimenter’s orExpectation 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 appears to conflict with those expectations.^[4]

• Extreme aversion — the tendency to avoid extremes, being more likely to choose an option if it is the intermediate choice.
• Focusing effect — prediction bias occurring when people place too much importance on one aspect of an event; causes error in accurately predicting the utility of a future outcome.
• Framing — by using a too narrow approach or description of the situation or issue. Also framing effect — drawing different conclusions based on how data are presented.
• 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.
• Illusion of control — the tendency for human beings to believe they can control or at least influence outcomes that they clearly cannot.
• Impact bias — the tendency for people to overestimate the length or the intensity of the impact of future feeling states.
• Information bias — the tendency to seek information even when it cannot affect action.
• Irrational escalation — the tendency to make irrational decisions based upon rational decisions in the past or to justify actions already taken.
• Loss aversion — “the disutility of giving up an object is greater than the utility associated with acquiring it”.^[5] (see alsosunk cost effects andEndowment effect).
• Mere exposure effect — the tendency for people to express undue liking for things merely because they are familiar with them.
• Moral credential effect — the tendency of a track record of non-prejudice to increase subsequent prejudice.
• Need for closure — the need to reach a verdict in important matters; to have an answer and to escape the feeling of doubt and uncertainty. The personal context (time or social pressure) might increase this bias.^[6]
• Neglect of probability — the tendency to completely disregard probability when making a decision under uncertainty.
• Not Invented Here — the tendency to ignore that a product or solution already exists, because its source is seen as an “enemy” or as “inferior”.
• Omission bias — the tendency to judge harmful actions as worse, or less moral, than equally harmful omissions (inactions).
• 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 fallacy — the tendency to underestimate task-completion times.
• Post-purchase rationalization — the tendency to persuade oneself through rational argument that a purchase was a good value.
• Pseudocertainty effect — the tendency to make risk-averse choices if the expected outcome is positive, but make risk-seeking choices to avoid negative outcomes.
• 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.
• Selective perception — the tendency for expectations to affect perception.
• Status quo bias — the tendency for people to like things to stay relatively the same (see also loss aversion, endowment effect, and system justification).^[7]
• Von Restorff effect — the tendency for an item that “stands out like a sore thumb” to be more likely to be remembered than other items.
• Wishful thinking — the formation of beliefs and the making of decisions according to what is pleasing to imagine instead of by appeal to evidence or rationality.
• Zero-risk bias — preference for reducing a small risk to zero over a greater reduction in a larger risk.

Biases in probability and belief

Many of these biases are often studied for how they affect business and economic decisions and how they affect experimental research.

• Ambiguity effect — the avoidance of options for which missing information makes the probability seem “unknown”.
• Anchoring — the tendency to rely too heavily, or “anchor,” on a past reference or on one trait or piece of information when making decisions.
• Attentional bias — neglect of relevant data when making judgments of a correlation or association.
• Authority bias — the tendency to value an ambiguous stimulus (e.g., an art performance) according to the opinion of someone who is seen as an authority on the topic.
• Availability heuristic — estimating what is more likely by what is more available in memory, which is biased toward vivid, unusual, or emotionally charged examples.
• 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”).
• Clustering illusion — the tendency to see patterns where actually none exist.
• Capability bias — The tendency to believe that the closer average performance is to a target, the tighter the distribution of the data set.
• Conjunction fallacy — the tendency to assume that specific conditions are more probable than general ones.
• 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 normal distribution. 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.”
• Hawthorne effect — the tendency of people to perform or perceive differently when they know that they are being observed.
• Hindsight bias — sometimes called the “I-knew-it-all-along” effect, the inclination to see past events as being predictable.
• Illusory correlation — beliefs that inaccurately suppose a relationship between a certain type of action and an effect.
• Ludic fallacy — the analysis of chance related problems according to the belief that the unstructured randomness found in life resembles the structured randomness found in games. Ignoring the non-gaussian distribution of many real-world results.
• Neglect of prior base rates effect — the tendency to neglect known odds when reevaluating odds in light of weak evidence.
• 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 alsosubject-expectancy effect).
• Optimism bias — the systematic tendency to be over-optimistic about the outcome of planned actions.
• Ostrich effect — ignoring an obvious (negative) situation.
• Overconfidence effect — excessive confidence in one’s own answers to questions. For example, for certain types of question, answers that people rate as “99% certain” turn out to be wrong 40% of the time.
• Positive outcome bias — a tendency in prediction to overestimate the probability of good things happening to them (see also wishful thinking, optimism bias, andvalence effect).
• Patternicity effect^[8] — the tendency to find meaningful patterns in meaningless noise.
• Primacy effect — the tendency to weigh initial events more than subsequent events.
• Recency effect — the tendency to weigh recent events more than earlier events (see also peak-end rule).
• Disregard of regression toward the mean — the tendency to expect extreme performance to continue.
• Reminiscence bump — the effect that people tend to recall more personal events from adolescence and early adulthood than from other lifetime periods.
• Rosy retrospection — the tendency to rate past events more positively than they had actually rated them when the event occurred.
• Selection bias — a distortion of evidence or data that arises from the way that the data are collected.
• Stereotyping — expecting a member of a group to have certain characteristics without having actual information about that individual.
• Subadditivity effect — the tendency to judge probability of the whole to be less than the probabilities of the parts.
• Subjective validation — perception that something is true if a subject’s belief demands it to be true. Also assigns perceived connections between coincidences.
• Telescoping effect — the effect that recent events appear to have occurred more remotely and remote events appear to have occurred more recently.
• Texas sharpshooter fallacy— the fallacy of selecting or adjusting a hypothesis after the data is collected, making it impossible to test the hypothesis fairly. Refers to the concept of firing shots at a barn door, drawing a circle around the best group, and declaring that to be the target.

Social biases

Most of these biases are labeled as attributional biases.

• Actor-observer bias — the tendency for explanations of other individuals’ behaviors to overemphasize the influence of their personality and underemphasize the influence of their situation (see also fundamental attribution error). However, this is coupled with the opposite tendency for the self in that explanations for our own behaviors overemphasize the influence of our situation and underemphasize the influence of our own personality.
• Dunning-Kruger effect — “…when people are incompetent in the strategies they adopt to achieve success and satisfaction, they suffer a dual burden: Not only do they reach erroneous conclusions and make unfortunate choices, but their incompetence robs them of the ability to realize it. Instead, …they are left with the mistaken impression that they are doing just fine.”^[9](see alsoLake Wobegon effect, andoverconfidence effect).
• Egocentric bias — occurs when people claim more responsibility for themselves for the results of a joint action than an outside observer would.
• Forer effect (aka Barnum Effect) — the tendency to 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. For example,horoscopes.
• False consensus effect — the tendency for people to overestimate the degree to which others agree with them.
• Fundamental attribution error — the tendency for people to over-emphasize personality-based explanations for behaviors observed in others while under-emphasizing the role and power of situational influences on the same behavior (see also actor-observer bias, group attribution error, positivity effect, and negativity effect).
• Halo effect — the tendency for a person’s positive or negative traits to “spill over” from one area of their personality to another in others’ perceptions of them (see also physical attractiveness stereotype).
• Herd instinct — Common tendency to adopt the opinions and follow the behaviors of the majority to feel safer and to avoid conflict.
• Illusion of asymmetric insight — people perceive their knowledge of their peers to surpass their peers’ knowledge of them.
• Illusion of transparency — people overestimate others’ ability to know them, and they also overestimate their ability to know others.
• Illusory superiority — perceiving oneself as having desirable qualities to a greater degree than other people. Also known as Superiority bias.
• Ingroup bias — the tendency for people to give preferential treatment to others they perceive to be members of their own groups.
• Just-world phenomenon — the tendency for people to believe that the world is “just” and therefore people “get what they deserve.”
• Lake Wobegon effect — the phenomenon that a supermajority of people report themselves as above average in desirable qualities (see also worse-than-average effect andoptimism bias).
• Money illusion – an irrational notion that the arbitrary values of currency, fiat or otherwise, have an actual immutable value.
• Notational bias — a form of cultural bias in which a notation induces the appearance of a nonexistent natural law.
• Outgroup homogeneity bias— individuals see members of their own group as being relatively more varied than members of other groups.
• Projection bias — the tendency to unconsciously assume that others share the same or similar thoughts, beliefs, values, or positions.
• Self-serving bias — the tendency to claim more responsibility for successes than failures. It may also manifest itself as a tendency for people to evaluate ambiguous information in a way beneficial to their interests (see also group-serving bias).
• Self-fulfilling prophecy — the tendency to engage in behaviors that elicit results which will (consciously or not) confirm our beliefs.
• System justification — 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. (See also status quo bias.)
• Trait ascription bias — the tendency for people to view themselves as relatively variable in terms of personality, behavior and mood while viewing others as much more predictable.
• Ultimate attribution error — Similar to the fundamental attribution error, in this error a person is likely to make an internal attribution to an entire group instead of the individuals within the group.

Memory errors

• Consistency bias — incorrectly remembering one’s past attitudes and behaviour as resembling present attitudes and behaviour.
• Cryptomnesia — a form ofmisattribution where a memory is mistaken for imagination.
• 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 being bigger than it was
• False memory — confusion of imagination with memory, or the confusion of true memories with false memories.
• Hindsight bias — filtering memory of past events through present knowledge, so that those events look more predictable than they actually were; also known as the ‘I-knew-it-all-along effect’.
• Self-serving bias — perceiving oneself responsible for desirable outcomes but not responsible for undesirable ones.
• Suggestibility — a form ofmisattribution where ideas suggested by a questioner are mistaken for memory.