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Ambiguity bias, also known as the ambiguity effect, is a cognitive bias where individuals tend to favor options with known probabilities over those where the probabilities are unknown or ambiguous. This bias stems from a human inclination toward certainty and aversion to unknown risks. When faced with choices, people often prefer what they can understand and predict, even if the predictable choice offers a lesser benefit than an ambiguous one.
Anchoring is the pull of an initial number, price, or estimate on later judgment — even when the starting point is arbitrary. We adjust away from the anchor, but usually not far enough.
The anecdotal fallacy is a cognitive bias where a person relies on personal stories or isolated examples instead of sound arguments or statistical evidence. This fallacy occurs when anecdotal evidence is used in an attempt to prove a point, even when it's not representative of a typical experience. It often disregards broader statistical realities, leading to erroneous conclusions based on sparse data.
The Appeal to Probability fallacy occurs when it is assumed that because something could happen, it will happen. This logical fallacy simplifies complex probabilities into certainties, overlooking other possibilities and uncertainties. It often leads to misleading conclusions and decisions.
The Argument from Fallacy, also known as the fallacy fallacy, is a logical fallacy that assumes that just because an argument contains a fallacy, its conclusion must necessarily be false. This cognitive bias is a form of misinterpretation where individuals erroneously conclude that the presence of flawed reasoning invalidates a proposition's truth.
Attentional bias is a cognitive bias that describes the tendency for people's perception to be affected by their recurring thoughts at the time. It occurs when individuals give disproportionate attention to certain stimuli while ignoring others, often leading to distorted or incomplete perspectives.
Authority bias is giving a claim extra weight because it comes from a prestigious, powerful, or credentialed person, beyond what their relevant evidence and expertise justify. Authority becomes a substitute for checking the claim itself.
Automation bias is a specific cognitive bias where humans disproportionately favor information or suggestions output by automated systems, sometimes to the detriment of other important data or their own judgment. This bias can lead individuals to overlook errors or incorrect recommendations made by machines. It is particularly prevalent in situations where automated systems are designed to aid decision-making processes.
An availability cascade is a self-reinforcing cycle in which a claim or risk becomes more believed simply because it is more discussed: media coverage makes it mentally available, availability makes it feel true and important, which generates more coverage and social pressure to agree. Public perception can thereby detach almost completely from underlying facts.
The availability heuristic is judging frequency, danger, or importance by how easily examples come to mind. What is vivid, recent, emotional, or repeatedly covered by media feels common — even when the base rate says otherwise.
The backfire effect is the proposed possibility that a correction makes a false belief stronger rather than weaker. It became a popular explanation for polarized debate, but large studies suggest it is rare; resistance to correction is real, yet people usually become more accurate when given a clear correction.
The bandwagon effect is adopting a belief, product, or action because many other people appear to have adopted it. Popularity becomes a shortcut for truth, quality, or safety — and each new adopter makes the signal look stronger.
Belief bias is a type of cognitive bias that occurs when an individual's evaluation of the logical validity of an argument is influenced by the believability of the conclusion. People tend to accept conclusions that align with their existing beliefs and reject those that do not, regardless of the soundness of the supporting premises.
Belief perseverance is the tendency to maintain a belief even after the evidence that originally supported it has been completely discredited. Once a belief exists, it recruits its own supporting structure — explanations, connections, identity — and survives the removal of its foundations.
The bias blind spot is readily detecting bias in other people while treating our own judgment as unusually objective. Because our reasoning feels sincere from the inside, the absence of a felt motive is mistaken for the absence of bias.
The bystander effect is the tendency for individuals to be less likely to help — or act at all — when other people are present. Responsibility diffuses across the group, everyone assumes someone else will step in, and each person reads the others' inaction as evidence that action isn't needed.
Choice-supportive bias is revising memory so the option we chose looks better and the options we rejected look worse than they did at the time. The decision becomes evidence of its own quality.
The clustering illusion is seeing meaningful runs, clusters, or hot spots in data that random variation can produce on its own. Randomness is lumpy; we expect it to look more evenly mixed than it does.
Compassion fade is the tendency for empathy and willingness to help to decrease as the number of people in need increases. Concern peaks for a single identified individual and begins declining as early as the second person — the emotional inverse of what the arithmetic of suffering demands.
Confirmation bias is the tendency to treat evidence as a lawyer for what we already believe rather than a test of whether we are right. It shapes what we search for, notice, remember, and count as convincing — often without feeling like bias at all.
Congruence bias is a type of cognitive bias which occurs when individuals test a hypothesis by focusing primarily on evidence that directly supports it, rather than seeking out information which might disprove or challenge it. This bias emerges notably in environments where information is plentiful, prompting a preference for data that aligns with current beliefs, rather than a holistic examination.
The conjunction fallacy is judging a detailed story as more likely than a broader category that includes it. A description can feel highly representative, but 'A and B' can never be more probable than 'A' alone.
Conservatism cognitive bias refers to the tendency of individuals to insufficiently revise their beliefs when presented with new evidence. This bias falls under the broader category of information overload, as people tend to give disproportionate weight to their prior knowledge or beliefs and do not adequately adjust them with fresh information. The phenomenon is closely associated with the psychological difficulty of abandoning previously held concepts and the innate preference for consistency.
The continued influence effect is a cognitive bias where people continue to maintain beliefs based on misinformation, even after it has been debunked. Despite corrections and factual information being presented, the initial misinformation persists in influencing beliefs and decisions.
Declinism is a cognitive bias characterized by a pessimistic belief that a society or an institution is inexorably declining or worsening. This perception often overlooks positive change and growth, focusing instead on nostalgia for a perceived better past. Declinism influences how individuals assess both current conditions and future prospects, often leading to an irrational emphasis on negative aspects over positive developments.
The default effect is the tendency to end up with whatever option requires no action. Pre-selected choices are adopted at far higher rates than identical options requiring an active step — one of the largest and most reliable effects in behavioral science, and the workhorse of choice architecture.
The Delmore effect is the tendency to set clear, detailed, and articulate goals for the lower-priority areas of our lives, while our most important ambitions remain vague and unarticulated. Named after the poet Delmore Schwartz, it describes why people often have precise plans for minor tasks but only hazy intentions for the goals that matter most to them.
The Dunning–Kruger effect is the debated finding that low performers can overestimate their ability, partly because the knowledge needed to perform a task also helps a person judge performance. The popular caricature — ignorant people are always supremely confident and experts always humble — goes far beyond the evidence.
Duration neglect is a cognitive bias where the duration of an emotional experience has little impact on the overall retrospective evaluation of the event. Instead, the evaluation is disproportionately influenced by the peak (most extreme moment) and the end (final moment) of the experience.
Egocentric bias is a cognitive bias that leads individuals to rely heavily on their own perspective and experience when interpreting events and interactions with others. This bias can result in an overestimation of one’s contributions, influence, or knowledge in various situations.
The empathy gap is failing to appreciate how strongly a different emotional or bodily state will shape our own or another person's choices. Calm selves underestimate hunger, pain, fear, craving, anger, and stress; hot selves underestimate what calm reflection will want.
Escalation of commitment refers to a cognitive bias where individuals or organizations continue to invest in a decision despite clear evidence that it may be failing or no longer viable. This phenomenon occurs when those involved irrationally persist in a course of action due to prior investments of time, money, or resources.
Essentialism is a cognitive bias where individuals believe that certain categories, such as people, animals, or objects, have an inherent essence that gives them their identity. This bias often leads to overgeneralization and stereotyping, as individuals attribute fixed traits to members of these categories.
Extrinsic incentive error is a cognitive bias where people tend to overestimate the influence of extrinsic incentives (such as money or rewards) on others' behaviors, while undervaluing intrinsic motivations (like personal satisfaction or enjoyment). It can lead to a misunderstanding of why people perform certain actions or participate in activities.
The false consensus effect is a cognitive bias where people overestimate the degree to which their beliefs, attitudes, and opinions are shared by others. This bias leads to an inflated sense of one's own norms and opinions, often overgeneralizing them as common or typical among a larger group or population.
The framing effect is changing a choice by changing its presentation while leaving the underlying facts the same. A 90% survival rate and a 10% mortality rate describe the same outcome, yet they invite different feelings, attention, and decisions.
The frequency illusion, often called the Baader–Meinhof phenomenon, is the sense that something suddenly appears everywhere after we first notice it. Attention changes what enters awareness, and the new sightings are mistaken for evidence that the world changed.
The fundamental attribution error is the tendency to explain other people's behavior by character while underweighting the situation they were in. We see the person clearly and the pressures, incentives, and missing information around them only dimly.
Group attribution error is a cognitive bias in which individuals erroneously attribute the behaviors or characteristics of a group to all of its members, or vice versa. This bias stems from a tendency to generalize based on limited information, leading to misconceptions and stereotypes.
Groupthink is a mode of thinking in cohesive groups where the desire for harmony and consensus overrides realistic appraisal of alternatives. Members self-censor doubts, dissenters are pressured, and the group converges on a decision that many individuals privately question — while feeling more confident than any of them would alone.
The halo effect is letting one positive trait — attractiveness, prestige, polish, friendliness, a famous brand — spill into judgments about unrelated traits. A good first impression quietly becomes evidence of competence, honesty, or quality.
Hindsight bias is seeing an outcome as obvious after it happens and remembering our earlier uncertainty as smaller than it was. Once we know the answer, it becomes hard to reconstruct a world in which the answer was still unknown.
Hyperbolic discounting is a cognitive bias where individuals tend to prefer smaller, immediate rewards over larger, delayed rewards. This bias reflects the human tendency to reduce the perceived value of delayed outcomes, often leading to choices that contradict long-term interests.
The Identifiable Victim Effect is a cognitive bias that refers to the tendency of individuals to offer greater aid when a specific, identifiable individual is observed under hardship, as opposed to a large, vaguely explained group with the same need. This bias demonstrates how humans are more emotionally moved and compelled to act when faced with a particular person's plight rather than statistical information or a broader context.
The illusion of control is a cognitive bias wherein individuals overestimate their influence over external events. This bias leads them to believe that they have the power to control outcomes that are largely determined by external factors or chance.
The illusion of validity is a cognitive bias that occurs when people overestimate their ability to interpret and predict outcomes in situations based on limited information. It is part of the broader category of cognitive biases related to our need for meaning, specifically within storytelling scenarios wherein sparse data is available. This bias leads individuals to have unwarranted confidence in their predictions or judgments, often overlooking the foundational issues of insufficient data or the complexity of the situations.
Illusory correlation is a cognitive bias that describes the tendency to perceive a relationship between two variables even when no such relationship exists. This bias is particularly likely to occur with low-frequency variables or when the data is sparse. It often leads individuals to form and maintain specific beliefs or stereotypes based on misleading or insufficient information.
Illusory superiority, often referred to as the above-average effect, is a cognitive bias whereby individuals overestimate their own qualities and abilities relative to others. This phenomena leads people to believe they are better than average in various domains, including intelligence, performance, and other competencies.
The illusory truth effect is a cognitive bias that describes how repeated exposure to information can lead to its perception as more truthful or accurate, regardless of its veracity. This phenomenon occurs because repetition makes statements easier to process, and this ease is often misattributed to truthfulness.
The implicit associations cognitive bias refers to the automatic associations some individuals hold about groups of people, ingrained at an unconscious level. These associations can influence attitudes, judgments, and behaviors, often without the individual being aware of them. This bias falls under the broader category of implicit stereotypes, which are the unconscious beliefs and attitudes toward particular groups based on race, gender, age, or other factors.
In-group bias is favoring people we see as 'us' over people we see as 'them,' even when group membership is arbitrary and the evidence about individuals is equivalent. Belonging can quietly become a proxy for trust, competence, and deservingness.
Information bias is a cognitive bias that compels individuals to seek more information in situations where it may be irrelevant or redundant. This bias stems from the need for speed in decision-making, preferring simple and complete narratives over complex and ambiguous ones. Despite the illusion of informed action it provides, it often leads to inefficiencies and poor decision-making.
Insensitivity to sample size is a cognitive bias where individuals, when evaluating statistical evidence, tend to disregard the size of the sample from which the evidence originates. This bias leads to overgeneralization from small samples and underestimation of variability based on sample size.
The Just-world hypothesis is a cognitive bias that leads individuals to believe that the world is inherently fair and that people ultimately get what they deserve. This belief can shape the way individuals perceive events and the behavior of others, often leading to a skewed interpretation of reality.
The Law of Triviality, also known as Parkinson's Law of Triviality, describes a phenomenon where people give disproportionate weight and time to trivial issues while neglecting more complex and critical matters. This cognitive bias leads to decision-makers focusing on simple tasks that are easy to understand and discuss, rather than tackling the more significant issues that require deeper analysis.
Leveling and sharpening cognitive biases refer to the processes by which individuals simplify complex information and emphasize certain elements over others. These biases illustrate how people tend to minimize or exaggerate details when recalling events or experiences, often leading to misrepresentation or distortion of the original information.
Loss aversion is the tendency for a loss to hurt more than an equivalent gain feels good. It makes keeping what we have psychologically compelling, even when a neutral comparison of future outcomes would favor a change.
The mere exposure effect is a psychological phenomenon where people tend to develop a preference for things they are repeatedly exposed to. This cognitive bias suggests that familiarity with something can lead to affection, even if it was initially neutral or disinterested.
The misinformation effect is a cognitive bias that occurs when a person's memory of an event becomes less accurate due to the influence of post-event information. This phenomenon often leads to the creation of false memories and impacts an individual's ability to recall events as they actually occurred.
The Moral Credential Effect is a cognitive bias where an individual's prior ethical behavior gives them a license to engage in potentially unethical actions without feeling guilty or damaging their self-image. It occurs when having previously made a moral choice allows someone to feel less compelled to act morally in subsequent situations.
Motivated reasoning is the tendency to process information in ways that arrive at the conclusions we want to reach, while experiencing the process as objective. Desired conclusions get asked 'Can I believe this?'; undesired ones get asked 'Must I believe this?' — two very different evidentiary bars.
Murphy's Law is a popular adage that states, 'Anything that can go wrong, will go wrong.' Although initially considered just a humorous observation about life, it reveals cognitive biases in how humans perceive and interpret unlikely and unfavorable events.
Naïve cynicism is a cognitive bias where individuals tend to assume that others are more egocentric, biased, or motivated by self-interest than themselves. This bias reflects a skepticism towards others' intentions and a belief that their actions are driven by self-serving motives.
Naïve realism is experiencing our own view as a direct reading of reality and explaining disagreement as ignorance, irrationality, or bias in the other person. We forget that our own attention, values, incentives, and prior beliefs also shape what looks obvious.
Negativity bias is giving bad news, criticism, threats, and losses more attention and weight than equally strong good news. One sharp negative signal can dominate a much larger body of positive or neutral evidence.
Neglect of probability is a cognitive bias where individuals disregard the probability of an event occurring and focus instead on the potential outcomes. This bias often leads to irrational decision-making because it prioritizes the emotional impact of potential outcomes over rational analysis of their likelihood. It is categorized under 'Lack of meaning' and is a subcategory of 'Stories in sparse data.'
Normalcy bias is a cognitive bias characterized by the refusal to plan for or react to a disaster which has never happened before. This bias leads individuals to underestimate both the likelihood of a disaster occurring and its potential impact, reinforcing a false sense of security.
The 'Not Invented Here' (NIH) bias refers to a cultural or psychological stance where individuals or organizations resist using, acquiring, or even acknowledging external knowledge, ideas, or solutions, simply because these innovations originate outside their own environment. This bias is characterized by the preference for internally developed products or ideas, often leading to skepticism and dismissal of externally sourced solutions.
Occam's Razor is a cognitive bias and philosophical principle that suggests that, among competing hypotheses that predict equally well, the one with the fewest assumptions should be selected. It promotes simplicity in decision-making and problem-solving, suggesting that simpler ideas with less complexity are often more likely to be correct.
Omission bias is judging harm caused by action as worse than equal harm caused by inaction. Doing nothing feels morally cleaner because the causal role is less visible, even when the decision to refrain was itself a choice.
Optimism bias is expecting better outcomes for ourselves than for similar other people. We accept the general risk — layoffs, illness, delays, losses — while quietly treating our own case as the exception.
The Ostrich Effect is a cognitive bias that describes the tendency of individuals to avoid negative or threatening information by metaphorically burying their heads in the sand, akin to the behavior of an ostrich. The bias is named after the common (though incorrect) belief that ostriches hide from danger by burying their heads in the sand.
Out-group homogeneity bias is seeing members of another group as more alike than members of our own group: 'they are all the same; we are a collection of individuals.' Distance hides variation while familiarity makes it visible.
Outcome bias is a cognitive bias that occurs when people judge the quality of a decision based on its outcome rather than the quality of the decision at the time it was made. This bias can lead to an inaccurate assessment of the decision-making process as it disregards the information available when the decision was made, focusing instead on the result.
Overconfidence is believing a judgment is more accurate, a skill stronger, or an outcome more controllable than the evidence warrants. Its most useful form is overprecision: confidence intervals that are far too narrow for how uncertain the world really is.
The peak-end rule is a cognitive bias that impacts how people retrospectively evaluate experiences. According to this rule, individuals tend to judge experiences based largely on how they felt at the most intense point (the peak) and at the end, rather than on the total sum or average of every moment of the experience.
The picture superiority effect is a cognitive bias that suggests images and pictures are more likely to be remembered than words. This phenomenon indicates that when information is presented as both pictures and text, the visual representation tends to be retained more effectively in our memory.
Prejudice is a negative or hostile evaluation of people because of their group membership. Unlike a stereotype, which is a generalized belief, prejudice includes an evaluative attitude that can shape attention, trust, and treatment before individual evidence is considered.
The primacy effect is remembering or overweighting what came first in a sequence. Early items receive more attention and rehearsal, and early impressions can become the frame through which later information is interpreted.
Pro-innovation bias is a cognitive bias that occurs when an individual or group overvalues the benefits of a new product or innovation while underestimating its limitations and challenges. It leads people to favor new ideas and technologies, often without thoroughly examining their impact or potential drawbacks.
Projection bias is assuming that future preferences will resemble the preferences we feel right now. Hunger, excitement, loneliness, motivation, and fear masquerade as stable information about what our future selves will want.
Proportionality bias is the intuition that big events must have big causes — that a world-changing outcome cannot plausibly stem from a trivial, random, or lone-actor cause. It is a core engine of conspiracy thinking and of over-engineered corporate postmortems alike.
The pseudocertainty effect is a cognitive bias that refers to individuals' tendency to make risk-averse choices when outcomes are framed as gains, and risk-seeking choices when they are framed as losses. This occurs despite the objective probabilities and outcomes remaining the same. The bias highlights how problem framing can significantly influence decision-making, particularly under conditions of uncertainty.
Reactance is the urge to reassert freedom when a message, rule, or person feels controlling. A threatened option can become more attractive precisely because someone appears to be taking it away.
Reactive devaluation is a cognitive bias where an individual devalues or dismisses proposals or ideas if they originate from an adversary or an opposing party, even if these ideas could be beneficial. This bias often stems from an emotional response, leading people to focus more on the source than the content, thereby affecting negotiations, decision-making, and conflict resolution.
The recency effect is remembering or overweighting what came last because it is still active in short-term memory. The newest information can feel most representative even when it is only the latest item in a longer record.
The Rhyme as reason effect, also known as the 'Eaton-Rosen phenomenon,' is a cognitive bias where people perceive rhyming statements as more truthful or accurate compared to non-rhyming equivalents. This effect capitalizes on the human inclination towards simple, complete phrases over complex or ambiguous ones, suggesting that a statement's form can significantly influence its perceived truthfulness.
Rosy retrospection is a cognitive bias that leads people to perceive past events as more favorable than they actually were. Individuals often remember the past with idealized positivity, overlooking negative aspects and enhancing positive ones. This bias influences how memories are recalled and interpreted, often painting a 'rosier' picture of the past than what the reality might have been.
Salience bias is the tendency to focus on information that is vivid, emotionally striking, or perceptually prominent while neglecting information that is duller but often more important. What grabs attention gets weighted; what doesn't, effectively doesn't exist for the decision.
Scope neglect is the tendency for our valuation of a problem to be nearly insensitive to its size. People will pay about the same to save 2,000, 20,000, or 200,000 birds; the emotional image driving the judgment — one oil-soaked bird — doesn't scale, so the numbers barely register.
Selective perception is a cognitive bias that involves focusing on information that confirms existing beliefs while ignoring information that contradicts them. This phenomenon falls under the category of Information overload, where individuals are faced with vast amounts of data and selectively filter it, often unconsciously, leading to reinforcement of pre-existing notions.
The self-relevance effect, a cognitive bias, is the tendency for individuals to better remember information that relates to themselves than information that has less personal relevance. This bias fundamentally affects how we process and prioritize the vast amount of information we encounter daily, making personally relevant information particularly salient.
Self-serving bias is claiming personal credit for success while assigning failure to circumstances, luck, or other people. The same evidence gets two attribution rules, both of which protect a flattering view of the self.
The Semmelweis reflex is a cognitive bias wherein people tend to reject new evidence or knowledge if it contradicts established norms or beliefs. Named after Ignaz Semmelweis, a 19th-century Hungarian physician who discovered that hand-washing could drastically reduce childbed fever incidence, the term describes the tendency to dismiss or undervalue findings that conflict with accepted paradigms.
Shared information bias is the tendency of groups to spend their discussion time on information all members already know, while the unique knowledge held by individual members — often the information that would change the decision — never surfaces. Groups exist to pool knowledge, and this bias is precisely the failure to pool.
Social desirability bias is a cognitive bias where individuals tend to answer questions or behave in ways they perceive as being more socially acceptable, rather than being truthful or authentic. This often results in skewed data in surveys, interviews, and research, as people provide responses they believe will make them look favorable in the eyes of others.
Status quo bias is preferring the current arrangement because it is current, even when a fresh comparison would favor change. The costs of changing are vivid and immediate; the costs of staying put are familiar, dispersed, and easy to leave uncounted.
Stereotyping is using a broad belief about a group to infer traits, ability, motives, or behavior in a particular person. A category replaces individual evidence, often with more confidence than the evidence can support.
The subadditivity effect is a cognitive bias where individuals tend to judge the probability of a whole as less than the sum of its parts. In essence, people often underestimate the total probability of an event when it is broken down into component parts. This effect is prominent within the realm of probabilistic reasoning, where human intuition struggles to accurately assess combined probabilities.
Subjective validation, also known as the Forer effect, is a cognitive bias whereby people tend to perceive vague or general statements as highly accurate and applicable to themselves personally. This phenomenon explains why individuals often find personal meaning in ambiguous information, such as horoscopes or personality tests, which seem tailor-made for them but are, in reality, generalized.
The sunk-cost fallacy is continuing a course of action because of time, money, or effort already spent, even though that investment cannot be recovered. The past feels like a reason to continue; economically, only the value and cost from this moment forward should decide.
Survivorship bias is drawing conclusions from the winners we can see while missing the failures that vanished from view. The visible sample feels like the whole population, so success looks more common — and more easily copied — than it really is.
System justification is the tendency to defend, rationalize, and see as legitimate the existing social, economic, and organizational arrangements one lives under — even when those arrangements work against one's own interests. The status quo isn't just preferred; it gets moralized.
The third-person effect is a cognitive bias where individuals believe that other people are more affected by media messages than they are themselves. This perception can lead people to overestimate the influence of media on others while underestimating its effect on themselves.
Ultimate attribution error is a cognitive bias that leads to the systematic attribution of behaviors of individuals or groups based on perceived inherent characteristics, especially in cases involving in-group versus out-group dynamics. This often results in attributing positive actions of in-group members to inherent traits and negative actions to situational factors, while interpreting out-group members' positive behaviors as situational and negative behaviors as inherent.
Zero sum bias is a cognitive bias where individuals perceive a situation as having a fixed amount of resources or benefits, leading them to think that one person's gain is inherently another's loss. This misperception often overlooks the possibility of non-zero-sum scenarios where all parties can benefit.