Cognitive biases · 131

A cognitive bias is a systematic pattern in how we perceive, remember and judge: a mental shortcut that usually works and sometimes misleads.

By group All, most common first

Ordered from most to least common in everyday arguments, decisions and media (the dots show how common). This is an editorial judgment, not a measured statistic. Chips show where a bias appears in Munger's list, Dobelli's list and others.

What we notice 20What it means 20Deciding and acting 42People and groups 19Memory 6Numbers, probability and prediction 13The self 11

What we notice: filtering too much information

We cannot attend to everything, so we filter, and the filter is not neutral.

  1. 1Confirmation bias Dobelli #7Dobelli #8
    The tendency to look for, notice, favour and remember information that confirms what we already believe, and to discount what contradicts it.
  2. 2Availability heuristic Munger #18Dobelli #11Kahneman #2
    Judging how likely or frequent something is by how easily examples come to mind, so vivid, recent or emotional events get overweighted.
  3. 3Anchoring Dobelli #30Kahneman #3
    Relying too heavily on the first number or piece of information encountered (the anchor) and adjusting too little from it.
  4. 12Framing effect Dobelli #42Kahneman #4
    Reacting differently to the same facts depending on how they are presented, for instance as a gain or a loss, a percentage or a count.
  5. 13Negativity bias
    Giving more weight to bad news, criticism and negative events than to equally strong positive ones.
  6. 14Survivorship bias Dobelli #1
    Drawing conclusions from the winners who remain visible while overlooking the many that dropped out, so success looks easier or likelier than it is.
  7. 15Illusory truth effect
    Coming to believe statements that are repeated, because familiarity feels like truth, even when we once knew better.
  8. 38Salience bias Dobelli #83
    Overweighting what stands out (vivid, unusual, emotional) and underweighting what is dull but important.
  9. 39Primacy and recency effects Dobelli #73
    Remembering, and weighting, the first and last items in a sequence more than those in the middle.
  10. 40Contrast effect Munger #16Dobelli #10
    Judging something by comparison with what was just seen rather than on its own merits.
  11. 41Mere-exposure effect
    Preferring things merely because they are familiar.
  12. 42Belief bias
    Judging the strength of an argument by whether its conclusion seems believable rather than by whether the logic is valid.
  13. 43Bias blind spot
    Seeing bias in other people's thinking more readily than in one's own.
  14. 44Dunning-Kruger effect
    People with little knowledge of a skill tend to overestimate their competence, while experts may underestimate theirs.
  15. 45Self-selection bias Dobelli #47
    Samples that choose themselves (volunteers, respondents, subscribers) differ systematically from the population, skewing conclusions.
  16. 46Availability cascade
    A self-reinforcing loop in which a claim gains plausibility simply because it is repeated in public discussion, which makes it more available, which makes it repeated more.
  17. 47Curse of knowledge
    Finding it hard to imagine not knowing something you know, so explanations skip steps and the audience is overestimated.
  18. 88Information bias Dobelli #59
    Seeking more information even when it cannot change the decision, which delays action.
  19. 89Feature-positive effect Dobelli #95
    Noticing what is present far more than what is absent, so missing evidence and missing features go unnoticed.
  20. 90Inattentional blindness Dobelli #88
    Failing to notice clearly visible things when attention is elsewhere, while believing we see everything.

What it means: finding patterns and stories

When facts are thin or random we fill in meaning, and the stories we tell feel more solid than they are.

  1. 4Fundamental attribution error Dobelli #36
    Explaining other people's behaviour by their character while explaining our own by circumstances.
  2. 16Halo effect Dobelli #38
    Letting one good impression (looks, charm, one success) colour judgment of unrelated traits; the reverse, from one bad trait, is the horn effect.
  3. 17Narrative fallacy Dobelli #13
    Weaving scattered facts into a tidy cause-and-effect story, and trusting the story because it is coherent rather than because it is true.
  4. 18Stereotyping
    Assuming that a person has characteristics because of the group they belong to, ignoring individual differences.
  5. 19Representativeness heuristic Kahneman #1
    Judging probability by how closely something resembles a typical example, while ignoring base rates and sample size.
  6. 48Clustering illusion Dobelli #3
    Seeing meaningful streaks, clusters or patterns in random data.
  7. 49Apophenia
    Perceiving connections or meaning in unrelated things, such as faces in clouds or omens in coincidences.
  8. 50Forer effect Dobelli #64
    Accepting vague, general descriptions as personal and accurate, which is why horoscopes and some personality tests feel uncannily right.
  9. 51Just-world hypothesis
    Believing that people generally get what they deserve and deserve what they get, which leads to blaming victims.
  10. 52Expectation effect Dobelli #62
    What we expect to happen changes what we perceive and sometimes what happens, through attention, behaviour and belief.
  11. 53Attribute substitution Kahneman #5
    Answering a hard question by unconsciously answering an easier one that feels related.
  12. 54What you see is all there is Kahneman #6
    Kahneman's phrase for building the most coherent story from whatever information is at hand, without asking what is missing.
  13. 91Introspection illusion Dobelli #67
    Believing we know why we think, feel or choose as we do by looking inward, when the real causes are often hidden from us.
  14. 92Swimmer's body illusion Dobelli #2
    Mistaking a trait that selected people into a group for an effect of the group's activity.
  15. 93Personification Dobelli #87
    Attributing human intentions, emotions or character to things, organizations and abstractions.
  16. 94Twaddle tendency Munger #23Dobelli #57
    Filling one's mind and conversation with trivia, noise and empty talk that crowds out what matters.
  17. 95Chauffeur knowledge Dobelli #16
    Mistaking the ability to talk fluently about a subject for real understanding.
  18. 96"Because" justification Dobelli #52
    People are more willing to comply when a request comes with a reason, even a meaningless one ("because I need to").
  19. 97Reason-respecting tendency Munger #24
    Munger's name for our habit of complying with, and giving, reasons, even poor ones: people want to know why, and any reason feels like enough.
  20. 98Wason selection task Dobelli #63
    Even simple "if P then Q" rules are often tested the wrong way: people look for confirming cases rather than the cases that could falsify the rule.

Deciding and acting: incentives, loss and commitment

We have to decide with limited time and information, and a handful of mental shortcuts decide for us.

  1. 5Overconfidence effect Dobelli #15Kahneman #8
    Being more certain of our judgments, knowledge and forecasts than their accuracy justifies.
  2. 6Loss aversion Munger #14Dobelli #32Kahneman #9
    Feeling a loss roughly twice as strongly as an equal gain, which makes us cling to what we have and avoid risk when ahead.
  3. 7Sunk-cost fallacy Dobelli #5
    Continuing an endeavour because of what has already been invested (time, money, effort) rather than by weighing future costs and benefits.
  4. 8Cognitive dissonance Dobelli #50
    The discomfort of holding conflicting beliefs or acting against our beliefs, which we reduce by changing the belief, the behaviour or the interpretation, usually the easiest of the three.
  5. 9Motivated reasoning
    Reasoning toward the conclusion we want, by scrutinising unwelcome evidence harshly and welcome evidence gently.
  6. 21Incentive super-response tendency Munger #1Dobelli #18
    People respond to rewards and punishments far more strongly and creatively than expected, often by gaming the metric rather than serving its purpose.
  7. 22Status quo bias
    A preference for things to stay as they are, so any change is judged against the current state as a loss.
  8. 23Endowment effect Dobelli #23
    Valuing something more simply because we own it.
  9. 24Optimism bias Munger #13
    Expecting good outcomes to be more likely, and bad ones less likely, for ourselves than for others.
  10. 25Planning fallacy Dobelli #91Kahneman #10
    Underestimating the time, cost and risk of our own plans while knowing similar plans overran, because we picture the best case.
  11. 26Outcome bias Dobelli #20
    Judging a decision by how it turned out rather than by the quality of the reasoning at the time it was made.
  12. 27Hyperbolic discounting Dobelli #51
    Preferring a smaller reward now to a larger one later, with the preference flipping as the "now" gets closer.
  13. 28Scarcity error Dobelli #27Cialdini #6
    Valuing something more when it appears limited in supply or time.
  14. 29Affect heuristic Dobelli #66Kahneman #11
    Letting how we feel about something ("good" or "bad") stand in for a judgment of its risks and benefits.
  15. 60Action bias Dobelli #43
    Preferring to do something, even something useless or harmful, over doing nothing in uncertain situations.
  16. 61Omission bias Dobelli #44
    Judging harm caused by action as worse than equal harm caused by inaction.
  17. 62Default effect Dobelli #81
    Sticking with the pre-selected option, which is why defaults strongly shape behaviour.
  18. 63Fear of regret Dobelli #82
    Avoiding choices we might later regret, which can push us toward the safe or conventional option.
  19. 64Ambiguity aversion Dobelli #80
    Preferring a known risk over an unknown one, even when the unknown one might be better.
  20. 65Paradox of choice Dobelli #21
    More options can make decisions harder, less satisfying and more regretful.
  21. 66Decision fatigue Dobelli #53
    The quality of decisions can deteriorate after a long run of choices, pushing people toward defaults or shortcuts.
  22. 67Procrastination Dobelli #85
    Delaying tasks despite expecting to be worse off for the delay, often because present comfort outweighs future benefit.
  23. 68Hedonic treadmill Dobelli #46
    We return to a baseline level of happiness after good or bad changes, so we underestimate adaptation and overestimate how much a purchase or promotion will help.
  24. 69Mental accounting
    Treating money differently depending on where it came from or what it is for, although money is fungible.
  25. 70Effort justification Dobelli #60
    Valuing an outcome more because we worked hard for it.
  26. 71Illusion of control Dobelli #17
    Overestimating how much influence we have over outcomes that are largely chance.
  27. 104House-money effect Dobelli #84
    Taking bigger risks with money that was won or windfall, as though it were not "really" yours.
  28. 105Winner's curse Dobelli #35
    In an auction with uncertain value, the winner tends to be the one who overestimated most, and so overpays.
  29. 106Motivation crowding Dobelli #56
    Paying for something people did out of intrinsic motivation can reduce their willingness to do it unpaid.
  30. 107Neomania Dobelli #69
    An excessive attraction to what is new, and an assumption that newer means better.
  31. 108Not-invented-here syndrome Dobelli #74
    Rejecting ideas, products or research because they came from outside one's own group.
  32. 109Inability to close doors Dobelli #68
    Keeping options open at a high cost in time, attention and money, even when they are nearly worthless.
  33. 110Overthinking Dobelli #90
    Analysing a decision at length to the point where it hurts the result, especially for intuitive or skilled tasks.
  34. 111Strategic misrepresentation Dobelli #89
    Deliberately understating costs and overstating benefits to win approval for a project.
  35. 112Déformation professionnelle Dobelli #92
    Seeing every problem through the lens of one's own profession or favourite tool.
  36. 113Zeigarnik effect Dobelli #93
    Unfinished tasks stay in mind more than finished ones, which can nag us or be exploited by cliffhangers.
  37. 114Illusion of skill Dobelli #94
    Mistaking luck for skill, especially where outcomes are largely random, such as stock picking.
  38. 115Domain dependence Dobelli #76
    Knowledge and skill that work in one context often fail to transfer to another, although we assume they will.
  39. 116Beginner's luck Dobelli #49
    Early success in a risky field is mostly chance, yet it can encourage overconfidence and more risk.
  40. 117Sleeper effect Dobelli #70
    A message from a low-credibility source gradually becomes more persuasive as people forget where it came from while remembering the message.
  41. 127"Get worse before it gets better" fallacy Dobelli #12
    A claim that gets worse before it improves is unfalsifiable: if things worsen it is "part of the process", and if they improve the claim is confirmed.
  42. 128Volunteer's folly Dobelli #65
    Dobelli's argument that donating money earned doing what you do best often helps a cause more than volunteering time on tasks others could do more cheaply.

People and groups: social influence

Much of what we believe and do is shaped by who is watching, who is speaking and who else is doing it.

  1. 10Social proof Munger #15Dobelli #4Cialdini #3
    Deciding what is correct or appropriate by looking at what others do, especially similar others, when we are uncertain.
  2. 30Authority bias Munger #22Dobelli #9Cialdini #4
    Giving undue weight to the opinion or commands of an authority figure, in matters even outside their expertise.
  3. 31Liking bias Munger #2Dobelli #22Cialdini #5
    Being more easily persuaded by, and more generous to, people we like, who are attractive, similar to us or flatter us.
  4. 32Reciprocity Munger #9Dobelli #6Cialdini #1
    Feeling obliged to return favours, gifts and concessions, even small or unrequested ones.
  5. 33Commitment and consistency Cialdini #2
    Once we commit to a position, even a small one, we feel pressure to act consistently with it.
  6. 34In-group bias Dobelli #79
    Favouring members of our own group and viewing outsiders less generously.
  7. 35Groupthink Dobelli #25
    A group's desire for harmony and consensus suppresses dissent and realistic appraisal of alternatives.
  8. 36Conformity
    Changing our judgment or behaviour to match the group, even when the group is clearly wrong.
  9. 72Unity Cialdini #7
    We are more easily influenced by people we see as "one of us", sharing group identity, origin or values.
  10. 73Disliking/hating tendency Munger #3
    Munger's counterpart to liking: a tendency to dislike people, groups or ideas that threaten our own, distorting facts in the process.
  11. 74Envy Munger #8Dobelli #86
    Resentment at others' advantages, which makes us judge by comparison and sometimes harm our own interests to reduce theirs.
  12. 75Social comparison bias Dobelli #72
    Judging our worth by comparison with others, and tending to dislike or undermine people who are better than us at something.
  13. 76Social loafing Dobelli #33
    People exert less effort in a group than alone when their contribution is not individually visible.
  14. 77False-consensus effect Dobelli #77
    Overestimating how widely our own opinions and behaviours are shared.
  15. 78Association bias Munger #10Dobelli #48
    Linking things that merely occur together or resemble each other, so we like or dislike something because of what it is associated with.
  16. 79News illusion Dobelli #99
    Consuming the news as if it made us better informed, when most of it is irrelevant, sensational, fleeting and crowds out deeper understanding.
  17. 118Contagion bias Dobelli #54
    Believing that a thing keeps the "essence" of what it touched, so objects associated with disliked people feel contaminated and those associated with admired ones feel special.
  18. 119Kantian fairness tendency Munger #7
    Munger's term for the expectation that everyone follows the same rules of fair play, shown by people who share a limited resource equally and by outrage when someone cuts in.
  19. 120Falsification of history Dobelli #78
    Rewriting our own or collective past, consciously or not, to fit our present beliefs and self-image.

Memory: what we keep and how we rewrite it

We reconstruct the past each time we recall it, and the reconstruction is shaped by the present.

  1. 11Hindsight bias Dobelli #14
    After learning the outcome, believing we knew it all along and that it was predictable.
  2. 85Rosy retrospection
    Remembering past events as more positive than they felt at the time.
  3. 86Peak-end rule
    Judging an experience mostly by its most intense moment and how it ended, not by its total or average.
  4. 87Misinformation effect
    Memories get altered by information received after the event, and we can recall events that never happened.
  5. 123Choice-supportive bias
    Remembering our past choices as better than they were, and the rejected options as worse.
  6. 124Alternative blindness Dobelli #71
    Judging an option on its own merits without asking "compared to what?", so a mediocre choice looks fine because the better alternatives never come into view.

Numbers, probability and prediction

We are poor intuitive statisticians, and the future is less predictable than it feels.

  1. 20Base-rate neglect Dobelli #28
    Ignoring how common something is in general when judging a specific case, and focusing on the vivid details instead.
  2. 55Law of small numbers Dobelli #61
    Expecting small samples to look like the whole population and drawing strong conclusions from a handful of cases.
  3. 56Regression to the mean Dobelli #19
    Extreme results tend to be followed by more ordinary ones, and we invent causes for this natural drift.
  4. 57Coincidences and unlikely events Dobelli #24
    Improbable things are bound to happen somewhere given enough chances, yet we read each one as meaningful.
  5. 58Exponential growth bias Dobelli #34
    Underestimating how quickly quantities grow when they compound.
  6. 59Neglect of probability Dobelli #26
    Focusing on how big or how dreadful an outcome would be and ignoring how likely it is, which is why tiny chances of huge prizes or disasters dominate decisions.
  7. 99Problem of induction Dobelli #31
    Past regularities do not guarantee future ones.
  8. 100Black swan events Dobelli #75
    Rare, high-impact events that nobody expected are explained away afterwards as if they had been predictable.
  9. 101Forecast illusion Dobelli #40
    Trusting precise predictions about complex systems (economies, markets, elections) far more than their track record deserves.
  10. 102Alternative paths Dobelli #39
    Judging a risky choice only by what happened, not by the other outcomes that could have happened.
  11. 103The problem with averages Dobelli #55
    An average can hide wide spread, skew and outliers, so it may describe nobody in the group.
  12. 125Will Rogers phenomenon Dobelli #58
    Moving an item from one group to another can raise the average of both groups, making things look better though nothing changed.
  13. 126Intention-to-treat error Dobelli #98
    Judging a treatment or programme only by the people who completed it, ignoring those who dropped out, who may have left because it was not working.

The self: ego, emotion and motivated belief

Psychological pressures from inside: how we protect our self-image and how our state of mind bends judgment.

  1. 37Self-serving bias Dobelli #45
    Crediting our successes to our own ability and our failures to circumstances or other people.
  2. 80Excessive self-regard tendency Munger #12
    Munger's name for over-rating ourselves, our possessions, our children and our decisions, and so being too slow to see our own faults.
  3. 81Simple, pain-avoiding psychological denial Munger #11
    Munger's term for distorting reality when facing it would be too painful.
  4. 82Doubt-avoidance tendency Munger #4
    The mind's urge to remove doubt by reaching a quick decision, especially under stress, which makes us jump to an answer rather than wait for evidence.
  5. 83Inconsistency-avoidance tendency Munger #5
    Munger's term for the mind's reluctance to change, which keeps old conclusions, habits and identities in place even when they should change.
  6. 84Lollapalooza effect Munger #25
    Munger's term for the extreme outcomes that arise when several psychological tendencies push in the same direction at once.
  7. 121Stress-influence tendency Munger #17
    Mild stress can sharpen performance, but extreme stress degrades judgment and can produce rigid or extreme reactions.
  8. 122Use-it-or-lose-it tendency Munger #19
    Skills and knowledge fade unless practised, and fluency needs constant use.
  9. 129Curiosity tendency Munger #6
    Munger counts curiosity among the helpful tendencies: when cultivated, it counters other biases by driving us to learn what is true.
  10. 130Drug-misinfluence tendency Munger #20
    Alcohol and other drugs, including addiction, distort judgment and behaviour, often while we feel fine.
  11. 131Senescence-misinfluence tendency Munger #21
    Ageing can reduce cognitive speed and flexibility, though the decline varies and can be slowed by keeping the mind active.