= List of cognitive biases =
Cognitive biases are tendencies to think in certain ways. Cognitive
biases can lead to systematic deviations from a standard of
rationality or good judgment, and are often studied in psychology and
Although the reality of these biases is confirmed by replicable
research, there are often controversies about how to classify these
biases or how to explain them. Some are effects of
information-processing rules (i.e. mental shortcuts), called
'heuristics', that the brain uses to produce decisions or judgments.
Such effects are called 'cognitive biases'. Biases in judgment or
decision-making can also result from motivation, such as when beliefs
are distorted by wishful thinking. Some biases have a variety of
cognitive ("cold") or motivational ("hot") explanations. Both effects
can be present at the same time.
There are also controversies as to whether some of these biases count
as truly 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. This kind of confirmation bias has been
argued to be an example of social skill: a way to establish a
connection with the other person.
The research on these biases overwhelmingly involves human subjects.
However, some of the findings have appeared in non-human animals as
well. For example, hyperbolic discounting has also been observed in
rats, pigeons, and monkeys.
Decision-making, belief, and behavioral biases
Many of these biases affect belief formation, business and economic
decisions, and human behavior in general. They arise as a replicable
result to a specific condition: when confronted with a specific
situation, the deviation from what is normally expected can be
* Ambiguity effect - the tendency to avoid options for which missing
information makes the probability seem "unknown."
* Anchoring or focalism - the tendency to rely too heavily, or
"anchor," on one trait or piece of information when making decisions.
* 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.
* 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.
* 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").
* Backfire effect - when people react to disconfirming evidence by
strengthening their beliefs.
* Bandwagon effect - the tendency to do (or believe) things because
many other people do (or believe) the same. Related to groupthink and
* Base rate fallacy or base rate neglect - In a sequence of
probabilities, the tendency to ignore the first.
* Belief bias - an effect where someone's evaluation of the logical
strength of an argument is biased by the believability of the
* 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.
* Choice-supportive bias - the tendency to remember one's choices as
better than they actually were.
* Clustering illusion - the tendency to over-expect small runs,
streaks, or clusters in large samples of random data (that is, seeing
* Confirmation bias - the tendency to search for, interpret and
remember information in a way that confirms one's preconceptions.
* Congruence bias - the tendency to test hypotheses exclusively
through direct testing, instead of testing possible alternative
* Conjunction fallacy - the tendency to assume that specific
conditions are more probable than general ones.
* or - the tendency to underestimate high values and high
likelihoods while overestimating low ones.
* Conservatism (Bayesian) - the tendency to insufficiently revise
one's belief when presented with new evidence.
* Contrast effect - the enhancement or reduction of a certain
perception's weight when compared with a recently observed,
* Curse of knowledge - when knowledge of a topic diminishes one's
ability to think about it from a less-informed (but more neutral)
* Decoy effect - preferences change when there is a third option that
is asymmetrically dominated
* Denomination effect - the tendency to spend more money when it is
denominated in small amounts (e.g. coins) rather than large amounts
* Distinction bias - the tendency to view two options as more
dissimilar when evaluating them simultaneously than when evaluating
* Duration 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.
* 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.
* Essentialism - categorizing people and things according to their
essential nature, in spite of variations.
* - based on the estimates, real-world evidence turns out to be less
extreme than our expectations (conditionally inverse of the
* 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.
* False-consensus effect - the tendency of a person to overestimate
how much other people agree with him or her.
* Functional fixedness - limits a person to using an object only in
the way it is traditionally used
* Focusing effect - the tendency to place too much importance on one
aspect of an event; causes error in accurately predicting the utility
of a future outcome.
* 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.
* Framing effect - drawing different conclusions from the same
information, depending on how or by whom that information is
* Baader-Meinhof Phenomenon - 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. (see also
* 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."
* Hard-easy effect - Based on a specific level of task difficulty, the
confidence in judgments is too conservative and not extreme enough
* 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. Colloquially referred to as "Hindsight is 20/20".
* Hostile media effect - the tendency to see a media report as being
biased, owing to one's own strong partisan views.
*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
* 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.
Also known as current moment bias, present-bias, and related to
* Identifiable victim effect - the tendency to respond more strongly
to a single identified person at risk than to a large group of people
* Illusion of control - the tendency to overestimate one's degree of
influence over other external events.
* Illusion of validity - when consistent but predictively weak data
leads to confident predictions
* Illusory correlation - inaccurately perceiving a relationship
between two unrelated events.
* Impact bias - the tendency 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.
* Insensitivity to sample size - the tendency to under-expect
variation in small samples
* 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
* 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).
* Less-is-better effect - a preference reversal where a dominated
smaller set is preferred to a larger set
* Loss aversion - "the disutility of giving up an object is greater
than the utility associated with acquiring it". (see also Sunk cost
effects and endowment effect).
* Ludic fallacy - the misuse of games to model real-life situations.
* Mere exposure effect - the tendency to express undue liking for
things merely because of familiarity with them.
* Mirror-imaging - the analysts' assumption that the people being
studied think like the analysts themselves.
* Money illusion - the tendency to concentrate on the nominal (face
value) of money rather than its value in terms of purchasing power.
* Moral credential effect - the tendency of a track record of
non-prejudice to increase subsequent prejudice.
* Negativity bias - the tendency to pay more attention and give more
weight to negative than positive experiences or other kinds of
* Neglect of probability - the tendency to completely disregard
probability when making a decision under uncertainty.
* Normalcy bias - the refusal to plan for, or react to, a disaster
which has never happened before.
* 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.
* 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
* Omission bias - the tendency to judge harmful actions as worse, or
less moral, than equally harmful omissions (inactions).
* Optimism bias - the tendency to be over-optimistic, overestimating
favorable and pleasing outcomes (see also wishful thinking, valence
effect, positive outcome bias).
* Ostrich effect - ignoring an obvious (negative) 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
* 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.
* 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.
* Pessimism bias - the tendency for some people, especially those
suffering from depression, to overestimate the likelihood of negative
things happening to them.
* Planning fallacy - the tendency to underestimate task-completion
* Post-purchase rationalization - the tendency to persuade oneself
through rational argument that a purchase was a good value.
*Pro-innovation bias - the tendency to reflect a personal bias towards
an invention/innovation, while often failing to identify limitations
and weaknesses or address the possibility of failure.
* 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 (see also Reverse psychology).
* Reactive devaluation - devaluing proposals that are no longer
hypothetical or purportedly originated with an adversary.
* 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').
* Recency illusion - the illusion that a phenomenon, typically a word
or language usage, that one has just begun to notice is a recent
innovation (see also frequency illusion).
* Restraint bias - the tendency to overestimate one's ability to show
restraint in the face of temptation.
* 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
* Risk compensation / Peltzman effect - the tendency to take greater
risks when perceived safety increases.
* Selective perception - the tendency for expectations to affect
* Semmelweis reflex - the tendency to reject new evidence that
contradicts a paradigm.
* 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.
* Social comparison bias - the tendency, when making hiring decisions,
to favour potential candidates who don't compete with one's own
* Social desirability bias - the tendency to over-report socially
desirable characteristics or behaviours and under-report socially
undesirable characteristics or behaviours.
* Status quo bias - the tendency to like things to stay relatively the
same (see also loss aversion, endowment effect, and system
* Stereotyping - expecting a member of a group to have certain
characteristics without having actual information about that
* Subadditivity effect - the tendency to estimate that the likelihood
of an event is less than the sum of its (more than two) mutually
* Subjective validation - perception that something is true if a
subject's belief demands it to be true. Also assigns perceived
connections between coincidences.
* 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.
* Texas sharpshooter fallacy - pieces of information that have no
relationship to one another are called out for their similarities, and
that similarity is used for claiming the existence of a pattern.
* 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.
*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.
* 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.
* Zero-risk bias - preference for reducing a small risk to zero over a
greater reduction in a larger risk.
* 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. The
frequency with which this bias occurs may be related to the social
dominance orientation personality factor.
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), and for explanations of one's own
behaviors to do the opposite (that is, to overemphasize the influence
of our situation and underemphasize the influence of our own
* Defensive attribution hypothesis - defensive attributions are made
when individuals witness or learn of a mishap happening to another
person. In these situations, attributions of responsibility to the
victim or harm-doer for the mishap will depend upon the severity of
the outcomes of the mishap and the level of personal and situational
similarity between the individual and victim. More responsibility will
be attributed to the harm-doer as the outcome becomes more severe, and
as personal or situational similarity decreases.
* Dunning-Kruger effect an effect in which incompetent people fail to
realise they are incompetent because they lack the skill to
distinguish between competence and incompetence
* Egocentric bias - occurs when people claim more responsibility for
themselves for the results of a joint action than an outside observer
would credit them.
* Extrinsic incentives bias - an exception to the 'fundamental
attribution error', when people view others as having (situational)
extrinsic motivations and (dispositional) intrinsic motivations for
* False consensus effect - the tendency for people to overestimate the
degree to which others agree with them.
* 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.
* 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).
* Group attribution error - the tendency to assume that group decision
outcomes reflect the preferences of group members, even when
information is available that clearly suggests otherwise.
* Halo effect - the tendency for a person's positive or negative
traits to "spill over" from one personality area to another in others'
perceptions of them (see also physical attractiveness stereotype).
* Illusion of asymmetric insight - people perceive their knowledge of
their peers to surpass their peers' knowledge of them.
* Illusion of external agency - when people view self-generated
preferences as instead being caused by insightful, effective and
* Illusion of transparency - people overestimate others' ability to
know them, and they also overestimate their ability to know others.
* Illusory superiority - overestimating one's desirable qualities, and
underestimating undesirable qualities, relative to other people. (Also
known as "Lake Wobegon effect," "better-than-average effect," or
* 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."
* Moral luck - the tendency for people to ascribe greater or lesser
moral standing based on the outcome of an event rather than the
* Naive cynicism - expecting more 'egocentric bias' in others than in
* 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
(or one's future selves) share one's current emotional states,
thoughts and values.
* 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).
* Spiral of silence - the process by which one opinion becomes
dominant as those who perceive their opinion to be in the minority do
not speak up because society threatens individuals with fear of
isolation. The assessment of one's social environment may not always
be correct with reality.
* 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
* 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
* Worse-than-average effect - a tendency to believe ourselves to be
worse than others at tasks which are difficult
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 (either
the chances that the memory will be recalled at all, or the amount of
time it takes for it to be recalled, or both), or that alters the
content of a reported memory. There are many types of memory bias,
* - bizarre, or uncommon material, is better remembered than common
* Choice-supportive bias - remembering chosen options as having been
better than rejected options
* - after an investment of effort in producing change, remembering
one's past performance as more difficult than it actually was
* Childhood amnesia - the retention of few memories from before the
age of four
* or Regressive Bias - tendency to remember high values and high
likelihoods/probabilities/frequencies lower than they actually were
and low ones 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 (e.g., recall time and accuracy for a work-related
memory will be lower at home, and vice versa)
* 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
* 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 (Self-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
easily found online.
* Hindsight bias - the inclination to see past events as being
predictable; also called the "I-knew-it-all-along" effect.
* - 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.
* - that people are more likely to identify as true statements those
they have previously heard (even if they cannot consciously remember
having heard them), regardless of the actual validity of the
statement. In other words, a person is more likely to believe a
familiar statement than an unfamiliar one.
* Illusory correlation - inaccurately remembering a relationship
between two events.
* Lag effect - see 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.
* Misinformation effect - that misinformation affects people's reports
of their own memory.
* - when information is retained in memory but the source of the
memory is forgotten. One of Schacter's (1999) Seven Sins of Memory,
Misattribution was divided into Source Confusion, Cryptomnesia and
False Recall/False Recognition.
* 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 via writing.
* - the improved recall of information congruent with one's current
* - that a person in a group has diminished recall for the words of
others who spoke immediately before or after this person.
* - that being intoxicated with a mind-altering substance makes it
harder to retrieve motor patterns from the Basal Ganglion.
* Part-list cueing effect - that being shown some items from a list
makes it 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 (e.g. pleasant or
unpleasant) and how it ended.
* - the unwanted recurrence of memories of a traumatic event.
* Picture superiority effect - that concepts are much more likely to
be remembered experientially if they are presented in picture form
than if they are presented in word form.
* - tendency of people to remember themselves as better than others
at tasks at which they rate themselves above average (also Illusory
superiority or Better-than-average effect) and tendency to remember
themselves as worse than others at tasks at which they rate themselves
below average (also Worse-than-average effect)
* Positivity effect - that older adults favor positive over negative
information in their memories.
* Primacy effect, Recency effect & Serial position effect - that
items near the end of a list are the easiest to recall, followed by
the items at the beginning of a list; items in the middle are the
least likely to be remembered.
* Reminiscence bump - the recalling of more personal events from
adolescence and early adulthood than personal events from other
* Rosy retrospection - the remembering of the past as having been
better than it really was.
* - that memories relating to the self are better recalled than
similar information relating to others.
* Self-serving bias - perceiving oneself responsible for desirable
outcomes but not responsible for undesirable ones.
* - misattributing the source of a memory, e.g. misremembering that
one saw an event personally when actually it was seen on television.
* Spacing effect - that information is better recalled if exposure to
it is repeated over a longer span of time.
* - memory distorted towards stereotypes (e.g. racial or gender),
e.g. "black-sounding" names being misremembered as names of criminals.
* - the weakening of the recency effect in the case that an 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.
* Subadditivity effect - the tendency to estimate that the likelihood
of a remembered event is less than the sum of its (more than two)
mutually exclusive components.
* 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 - that frequent testing of material that has been
committed to memory improves memory recall.
* 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 an instance of "blocking"
where multiple similar memories are being recalled and interfere with
* - that the "gist" of what someone has said is better remembered
than the verbatim wording
* 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.
Common theoretical causes of some cognitive biases
* Bounded rationality - limits on optimization and rationality
** Prospect theory
** Mental accounting
** Adaptive bias - basing decisions on limited information and biasing
them based on the costs of being wrong.
* Attribute substitution - making a complex, difficult judgment by
unconsciously substituting it by an easier judgment
* Attribution theory
** Naïve realism
* Cognitive dissonance, and related:
** Impression management
** Self-perception theory
* Heuristics in judgment and decision making, including:
** Availability heuristic - estimating what is more likely by what is
more available in memory, which is biased toward vivid, unusual, or
emotionally charged examples
** Representativeness heuristic - judging probabilities on the basis
** Affect heuristic - basing a decision on an emotional reaction
rather than a calculation of risks and benefits
* Some theories of emotion such as:
** Two-factor theory of emotion
** Somatic markers hypothesis
* Introspection illusion
* Misinterpretations or misuse of statistics; innumeracy.
A 2012 'Psychological Bulletin' article suggested that at least eight
seemingly unrelated biases can be produced by the same
information-theoretic generative mechanism that assumes noisy
information processing during storage and retrieval of information in
* Affective forecasting
* Black swan theory
* Cognitive bias mitigation
* Cognitive distortion
* Cross-race effect
* List of common misconceptions
* List of fallacies
* List of memory biases
* Lists of thinking-related topics
* List of topics related to public relations and propaganda
* Logical fallacy
* Media bias
* Publication bias
* Recall bias
* Systematic bias