The Dictionary of Cognitive Biases
The Dictionary of Cognitive Biases

The Dictionary of Cognitive Biases

Cognitive Bias Description
Ambiguity effect We tend to avoid options for which a probability of a favorable outcome is unknown.
Anchoring We tend to rely too heavily on one trait or piece of information hen making decisions (usually the first piece of information acquired on that subject)
Anthropocentric thinking We tend to use human analogies as a basis for reasoning about other, less familiar, biological phenomena.
Anthropomorphism We tend to characterize animals, objects and abstract concepts as possessing human-like traits, emotions and intentions.
Attentional bias Our recurring thoughts tend to affect our perception.
Automation bias We tend to depend excessively on automated systems which can lead to erroneous automated information overriding correct decisions.
Availability heuristics We tend 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.
Bandwagon effect We tend to do or believe things because many other people do so.
Base rate fallacy We tend to ignore generic information and focus on specifics.
Ben Franklink effect A person who has performed a favor for someone is more likely to do another favor for that person, than they would be if they had received a favor from that person.
Berkson’s paradox We tend to misinterpret statistical experiments involving conditional probabilities.
Bias blind spot We tend to see ourselves as less biased than others.
Choice-supportive bias We tend to remember one’s choice as better than they actually were.
Clustering illusion We tend to overestimate the importance of small runs, treats, or clusters in large samples of random data.
Confirmation bias We tend to search for, interpret, focus on and remember information in a way that confirms one’s perceptions.
Congruence bias We tend to test hypotheses exclusively through direct testing, instead of testing possible alternative hypotheses.
Conjunction fallacy We tend to assume specific conditions are more probable than general ones.
Conservatism We tend to revise our believes insufficiently when presented with new evidence.
Continued influence effect We tend to believe previously learned misinformation even after it has been corrected.
Contrast effect The enhancement or reduction of a certain stimulus’ perception when compared with a recently observed, contrasting object.
Courtesy bias We tend to give an opinion that’s more socially correct than one’s true opinion, so as to avoid offending anyone.
Curse of knowledge When communicating with people, we tend to assume they have the background to understand.
Declinism We are predisposed to view past favorably and future negatively.
Decoy effect Preferences for either option A or B change in favor of option B when option C is presented
Default effect We tend to choose a default one when given a choice between several options.
Denomination effect We tend to spend more money when it’s denominated in small amounts (e.g. coins than bills).
Disposition effect We tend to sell asset that has increased in value and resist selling asset that has declined in value.
Distinction bias We tend to view 2 options as more different when evaluating them simultaneously than when doing so separately.
Dunning-Kruger effect Unskilled individuals tend to overestimate their own abilities. Experts tend to underestimate their own abilities.
Empathy gap We tend to underestimate the influence or strength of feelings, in ourselves or others.
Endowment effect We tend to retain an object we own than acquire that same object when they do not own it.
Exaggerated expectation We tend to expect or predict more extreme outcomes than those outcomes actually happen.
Focusing effect We tend to place too much importance on one aspect of an event.
Framing effect We tend to draw different conclusions from the same information, depending on how that information is presented.
Gambler’s fallacy We tend to think that future probabilities are altered by past events, when in reality they’re unchanged.
Hindsight bias “I knew it all along” effect. We tend to see past events as being predictable.
Hostile attribution bias We tend to interpret other’s behaviors as having hostile intent, even when the behavior is ambiguous.
Hot-hand fallacy We who have experienced success with a random event believes we have a greater chance of further success in additional attempts.
Identifiable victim effect We tend to respond more strongly to a single identified person at risk than to a large group of people at risk.
IKEA effect We tend to place a disproportionately high value on objects that we partially assembled ourselves. Name after IKEA furniture.
Illusion of control We tend to overestimate one’s degree of influence over other external events.
Illusion of validity When available information is consistent, we tend to believe that our judgement are accurate.
Illusory correlation We tend to inaccurately perceive a relationship between two unrelated events.
Impact bias We tend to overestimate the length or intensity of the impact of future feeling states.
Information bias We tend to seek information even when it cannot affect action.
Less is better effect We tend to prefer a smaller set to a larger set judged separately, not jointly.
Look-elsewhere effect
Loss aversion We tend to prefer avoiding losses to acquiring equivalent gains (better not to lose $5 than to gain $5).
Mere exposure effect We tend to express undue liking for things merely because of familiarity with them.
Money illusion We tend to concentrate on the nominal value (face value) of money rather than its value in terms of purchasing power.
Negativity bias We tend to have a greater recall of unpleasant memories compared with positive memories.
Neglect of probability We tend to completely disregard probability when making a decision under uncertainty.
Normalcy bias We tend to refuse to plan for, or react to, a disaster which has never happened before.
Observer-expectancy effect When a researcher expects a given result, and therefore unconsciously manipulates an experiment in order to find it.
Omission bias We tend to judge harmful actions as worse, or less moral, than equally harmful inaction.
Optimism bias We tend to be over-optimistic, overestimating favorable and pleasing outcomes.
Ostrich effect We tend to ignore an obvious (negative) situation.
Outcome bias We tend 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 We tend to be excessively confident in one’s own answers to questions.
Pessimism bias We tend to overestimate the likelihood of negative things happening to us.
Planning fallacy We tend to underestimate task-completion times.
Post-purchase rationalization We tend to persuade oneself through rational argument that a purchase was a good value.
Present bias We tend to give stronger weight to payoffs that are closer to present time when considering trade-offs between two future moments.
Projection bias We tend to overestimate how much our future selves share one’s current preferences, thoughts and values, thus leading to sub-optimal choices.
Pseudo-certainty effect We tend to make risk-averse choices if we expect the positive outcome, but make risk-seeking choices to avoid negative outcomes.
Reactance We tend to do the opposite of what someone wants us to do out of a need to resist a perceived attempt to constrain our freedom of choice.
Restraint bias We tend to overestimate our ability to show restraint in the face of temptation.
Risk compensation We tend to take greater risks when perceived safety increases.
Salience bias We tend to focus on times that are more prominent or emotionally striking and ignore those that are unremarkable, even though this difference is often irrelevant by object standards.
Selection bias We tend 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.
Sexual over-perception bias We tend to over-/underestimate sexual interest of another person in ourselves.
Social desirability bias We tend to over-report socially desirable characteristics or behaviors in ourselves and under-report socially undesirable counterparts.
Status quo bias We tend to like things to stay relatively the same.
Stereotyping We expect a member of a group to have certain characteristics without having actual information about the individual.
Subadditivity effect We tend to judge probability of the whole to be less than the probabilities of the parts.
Survivorship bias We tend to concentrate on people or things that survived some process and inadvertently overlooking those that didn’t because of their lack of visibility.
Time-saving bias
Third-person effect We tend to believe that mass communicated media messages have a greater effect on others than on ourselves.
Well-traveled road effect We tend to underestimate the duration taken to traverse often-traveled routes and overestimate the less familiar counterparts.
Women are wonderful effect We tend to associate more positive attributes with women than with men.
Zero-risk bias We tend to prefer complete elimination of a risk even when alternative options have a greater reduction.
Zero-sum bias We tend to incorrectly perceive a situation as a zero-sum game (i.e., one person gains at the expense of another).
Social Biases
Actor-observer bias
Authority bias We tend to be more influenced by the opinion of an authority figure.
Cheerleader effect People tend to appear more attractive in a group than in isolation.
Egocentric bias
Extrinsic incentive bias We tend to view others has having (situational) extrinsic motivations and (dis-positional) intrinsic motivations for ourselves.
False consensus effect We tend to overestimate the degree to which others agree with us.
False uniqueness bias We tend to see our projects and ourselves as more unique than the actually are.
Fundamental attribution error We tend to overemphasize personal characteristics and ignore situational factors in judging others’ behaviors.
Group attribution error We tend to believe characteristics of an individual group member reflect the group as a whole.
Illusion of asymmetric insight We tend to perceive our knowledge of our peers to surpass their knowledge of us.
Illusion of external agency We tend to view self-generated preferences as instead being caused by insightful, effective and benevolent agents.
Illusion of transparency We tend to overestimate other’s ability to know themselves and we also overestimate our ability to know others.
Illusory superiority We tend to overestimate our desirable qualities and underestimate undesirable qualities, relative to other people.
Ingroup bias
Just-world hypothesis
Moral luck
Naïve cynicism
Naïve realism
Outgroup homogeneity bias We tend to see members of our own group as being relatively more varied than members of other groups.
Self-serving bias We tend to claim more responsibility for success than failures.
Shared information bias We tend to spend more time and energy discussing information that all members are familiar with, and less time and energy discussing information that only some members are aware of (i.e., unshared information).
System justification We tend to defender and bolster the status quo.
Trait ascription bias We tend to view ourselves as relatively variable in terms of personality, behavior, and mood while viewing others as much more predictable.
Ultimate attribution error Similar to fundamental attribution error, we tend to make internal attribution to entire group instead of the individuals within the group.
Worse-than-average effect We tend to believe ourselves to be worse than others at tasks which are difficult.
Memory Errors and Biases
Bizarreness effect We tend to remember bizarre material than common material.
Choice-supportive bias
Consistency bias We tend to incorrectly remember our past attitudes and behavior as resembling present attitudes and behaviors.
Context effect
Cross-race effect We tend to have difficulty identifying members of a race other than our own.
Cryptomnesia We tend to mistake a memory for imagination, because there is no subjective experience of it being a memory.
Egocentric bias We tend to rely too heavily on one’s own perspective and or have a higher opinion of oneself than reality.
Fading affect bias Our memories associated with negative emotions tend to be forgotten more quickly than those associated with positive emotions.
False memory We tend to mistake imagination for a memory.
Generation effect We tend to best remember self-generation information.
Google effect We tend to forget information that can be found readily online by using search engines.
Hindsight bias We tend to see past events as being more predictable than they actually were (aka I knew it all along effect)
Humor effect We tend to more easily remember humorous items than non-humorous ones.
Illusion of truth effect
Illusory correlation We tend to inaccurately remember a relationship between two events.
Lag effect Learning is greater when studying is spread out over time, as opposed to the same amount of time in a single session.
List-length effect We tend to remember a smaller percentage of items in a longer list, but as the length of the list increases, the absolute number of items remembered increases as well.
Misinformation effect Our memories tend to become less accurate due to interference from post-event information.
Modality effect We tend to recall the last items of a list better when they were received via speech rather than via writing.
Mood-congruent memory bias The better our mood, the improved recall of information we have.
Next-in-line effect We tend to be unable to recall information about events immediately before our turn to perform.
Peak-end rule We tend to judge an experience based on how we felt at its peak and at its end (rather than based on total sum or average of the journey)
Picture superiority effect We tend to remember pictures and images more than words.
Positivity effect The older we are the more we favor positive over negative information in our memories.
Primacy effect We tend to recall items near the end of a sequence easier, followed by those at the beginning. Items in the middle are least likely to be recalled
Processing difficulty effect The longer it takes to read and process information, the easier it is to be remembered.
Reminiscence bump We tend to recall more personal events from adolescence and early adulthood than those from other lifetime periods.
Rosy retrospection We tend to judge the past more positively than it really was.
Self-relevance effect We tend to better recall memories relating to self than those relating to others.
Source confusion
Spacing effect We tend to recall information that’s exposure is repeated over a span of time better than a short one.
Spotlight effect We tend to overestimate the amount that others notice our appearance or behavior.
Telescoping effect We tend to displace recent events backward in time and remote events forward in time, thereby recent events appear more remote, and remote events, more recent.
Testing effect We tend to retain information better that we have read by rewriting it rather rereading it.
Tip of the tongue phenomenon
Travis Syndrome We tend to overestimate the significance of the present.
Verbatim effect We tend to remember the essence of someone’s speech better than the wording they used.
von Restorff effect Aka isolation effect, we tend to remember things that stand out better than others.
Zeigarnik effect We tend to remember uncompleted or interrupted tasks better than completed ones.