Cognitive Biases and Fallacies

These are the biases and fallacies that define and distort how we understand the world around us.

While cognitive bias and fallacy crafts a false image relative to reality, most educated people don’t often realize that they’re very useful at making life more meaningful or easier:

  • There’s much less mental work from filtering out information or converting it into a story.
  • Quick-and-easy solutions lets us sift through much more information, even if it’s not that thorough.
  • By trusting things beyond ourselves, we get along in society more easily.
  • By honoring our fear impulses, we can successfully avoid most bad things that may happen, even if modern society often requires the opposite approach.
  • We can discover meaning and purpose from observations to give us something to live for, even when there’s nothing there.
  • Irrational behavior is often the most compassionate and loving, which is where the ultimate meaning of life resides.

While avoiding all these aren’t necessarily important to live a good and meaningful life, we must be aware of them to keep our imaginations and predictions tethered closely with reality.

It’s worth noting that awareness of these biases don’t necessarily change anything. We tend to veer into an opposite bias while trying to be accurate, and influencing others with incentives to be unbiased doesn’t help at all.

This is not a complete list, and probably can never be. It’s all based on a “rational actor model”, which implies that everyone is reasonable until distorted by a bias. The rational actor model is likely wrong.

Detecting Information

Availability heuristic/availability bias – we believe something is likely if we find 1 instance of it

Expectations bias – expectations we’ve predetermined define what we perceive

List-length effect – as lists grow, we remember more items in that list, but a smaller percentage of it

Priming – we’re constantly influenced by subconscious triggers

Tachypsychia – our perception of time lengthens and slows down

Weber-Fechner law – we detect increases in things proportionally to how many things there were at the beginning

Ignoring Information

Banner blindness/edge blindness – we learn to ignore what we repeatedly see

Cross-race effect/cross-race bias/other-race bias/own-race bias/other-race effect – we more easily recognize faces that match our racial group

Google effect/digital amnesia – we remember where something is, but not what it is

Memory inhibition/part-list cueing effect/repetition blindness – we don’t remember some items in a list or sequence because of other items

Next-in-line effect – we ignore information that came right after what we just said

No true Scotsman/purity appeal/perfect solution fallacy – we reject an idea because it doesn’t fit every criteria we feel about something

Normalcy bias/normality bias – we tend to ignore threat warnings

Plant bias – we ignore plants, including when valuing their importance and use

Selective perception/Ostrich effect/Semmelweis reflex – we ignore details we don’t like

Survivorship bias/survival bias/immortal time bias/swimmer’s body illusion – we neglect to notice things that don’t make it past a selection process

Mixing/Merging Information

Ad hominem – we mix up what we hear and why it was said

Anthropomorphism/anthropocentrism – we assume human-like traits and experiences for non-human things

Appeal to probability/appeal to possibility – we assume a likely thing is a guaranteed thing

Argument from ignorance – we accept strange explanations when we’re uncertain

Bulverism – we will claim A, and because of B want A to be true, so A is false

Circular reasoning/begging the question/petitio principii – our “why” questions can be answered sequentially in a loop

Cognitive dissonance – we can believe opposite things at the same time

Common source bias – we mix up information when it’s from the same source

Composition fallacy/frozen abstraction – we assume the qualities of a part are the qualities of the whole

Confabulation – we mix up information

Division fallacy – we assume the qualities of the whole are the qualities of the part

Illicit transference – we mix up things that are general principles for categories and specific things that don’t apply to everything in a category

Interoceptive bias/hungry judge effect – we are heavily influenced by external, unrelated circumstances

Masked-man fallacy – we believe that because A has Quality 1 and B doesn’t, because A has Quality 2 B can’t

Misinformation effect – we remember the wrong information because future information mixed with it

Memory misattribution/source misattribution – we forget where things went and fail in 3 ways:

  • Cryptomnesia – we think something we heard was our original thought
  • False memory – we believe something that didn’t happen actually happened
  • Source confusion – we misplace where we perceived something

Mental accounting – we group money and expected likelihoods into exclusive, unrelated categories

Nietzsche-Sapir-Whorf-Korzybski hypothesis/linguistic relativity hypothesis – we form language to organize and understand reality, not to simply clarify or communicate it

Placebo effect – we positively change our physiology and attitude because of things that didn’t do anything

Stolen concept fallacy – we use A to disprove B, but A logically depends on B to exist

Surrogation – we mix up the thing and the measurement of that thing

Telescoping effect – we misplace the chronology of past and future events

Tip of the tongue phenomenon – we can remember a feeling tied to a word, but not the word itself

Two negative premises – we believe that because A isn’t B, and B isn’t C, that A is C

Undistributed middle – we believe that because Object A and Object B have Quality A, that Object A is Object B

Prioritizing Memory

Attentional bias – we remember things better if we think about them more frequently

Attribute substitution – we use simple details when things get too complicated

Belief bias – we agree with conclusions based on our beliefs, not on logic

Bizarreness effect/humor effect – we remember odd or funny things more than mundane things

Boundary extension – we imagine the background of an image as larger than the foreground

Childhood amnesia – we forget most things before age 4

Continued influence effect/misinformation effect – we still remember wrong information even after we were corrected

Cue-dependent forgetting/context effect/mood-congruent memory bias – we recall memories based on how we’re thinking at the moment

Fading affect bias – we forget negative memories faster than positive ones

Generation effect – we remember things we thought more than things we observed

Implicit association – we remember words based on how closely connected we’ve made them

Isolation effect/Von Restorff effect – when we perceive multiple things, we remember the most different thing of all of them

Lag effect/spacing effect – we learn more easily when the information is spaced out over time

Mandela effect – we remember things that never happened

Memory inhibition effect – we partially don’t remember things

Perky effect – we mix up imagined and real images

Persistence – we re-experience painful past memories

Picture superiority effect – we remember pictures more than words

Reminiscence bump – we remember our adolescence and early adulthood more than most other periods of our lives

Serial position effect/list length effect – we remember the first and last things in a series the easiest

  • Anchoring bias/contrast effect/focusing effect/primacy effect/arbitrary coherence – we rely heavily on the first observed piece of information
  • Availability heuristic/recency bias/suffix effect/Travis syndrome – we prioritize recent and available information over older information

Suggestibility – we mistake someone’s question as our own thought

Unit bias – we feel one unit of something is the ideal amount

Crafting Stories

Anecdotal fallacy/spotlight fallacy/Volvo effect/hasty generalization/proof by example/no limits fallacy – we use personal experiences or isolated examples instead of sound arguments or compelling evidence

Apophenia/bucket errors/clustering illusion/illusory correlation – we connect unrelated information and believe they’re connected

Association fallacy – we conclude that if A is B and A is C, that B is also C

Converse error/affirming the consequent – we assume only A can cause B, and B, so therefore A

Denying the antecedent – we assume only A can cause B, and not A, so not B

False cause – we assume A coming before B means A caused B

Framing effect – we change our decisions based on whether the options were positively or negatively expressed

Frequency illusion/Baader-Meinhof effect – we start seeing something everywhere once we’ve noticed it

Pareidolia/Texas sharpshooter fallacy – we create meaning out of things that have no meaning

Peak-end rule/duration neglect – we measure an experience by its most intense point and how it ends, not by all its parts

Eaton-Rosen phenomenon/rhyme as reason effect – we consider things are more true when they rhyme

Levels-of-processing effect/testing effect/processing difficulty effect – we understand things better when we mentally process them more

Leveling and sharpening – we omit information from stories (leveling) and add specific details to our stories (sharpening)

Magical thinking/Tinker Bell effect – we make and believe stories that explain coincidences

Modality effect – we remember things based on how they’re presented

Red herring – we connect concepts that are only barely related

Salience bias – we focus on things that emotionally affect us more than things that don’t

Sample size insensitivity – we judge likelihoods while ignoring the number of events that had that likelihood

Storytelling effect – we remember stories more than facts

Verbatim effect – we remember the “gist” of something more than exact wording

Faster Selecting

Additive bias – we tend to solve problems by adding when we should be subtracting

Ambiguity effect – we prioritize decisions where things are more certain

Attentional bias – we filter thoughts based on what we’re paying attention to

Base rate fallacy – we prioritize individual information over general information

Cashless effect – we spend more when we don’t actually see our money

Centre-stage effect – we choose the middle option in a set of items

Decoy effect/attraction effect/assymetric dominance effect – we change our opinion of 2 options when a 3rd option is inherently worse than one of them and has pros and cons with the other

Default effect – we tend to choose the most standard option

Denomination effect – we tend to spend smaller amounts of money (e.g., coins) more quickly than larger amounts (e.g., banknotes)

Distinction bias – we find more differences between two things when we examine them together versus separately

Fallacy argument/fallacy appeal/Mister Spock fallacy – we assume a faulty premise automatically means a faulty conclusion

False dichotomy/false dilemma fallacy – we assume an either/or extreme and ignore other possibilities

Genetic fallacy – we assume something’s origin defines whether it’s true

Golden Mean fallacy – we assume the “middle ground” between two points is the best option

Group attractiveness effect – we find individual items more attractive when presented in a group

Ignorance appeal/ignorance argument/lack of imagination argument/personal incredulity argument – we assume something is true or false only because it hasn’t been proven otherwise

Law of the instrument/law of the hammer/Maslow’s gavel/golden hammer – the thing we use dictates how we perceive everything else

Less-is-better effect – we prefer smaller amounts of uneven comparisons when observing them separately, then reverse our preference when they’re observed together

Money illusion/price illusion – we measure money based on its relative number instead of what it can do for us

Prosecutor’s fallacy – we reject an event’s explanation even though our preferred expectation is even more unlikely

Reactive devaluation – we assume information from an enemy has less value

Fear of Missing Out

Action bias – we tend to act even when we shouldn’t

Fresh start effect – we take action if we feel there’s something new to it

Novelty appeal – we prefer things we think are new

Proudly found elsewhere (PFE) syndrome – we prefer using things from outside groups

Recency illusion – we believe a word is newer because we notice it, even when it’s been around for a long time

Zeigarnik effect/unit bias – we remember uncompleted or interrupted tasks more than completed ones

Fear of Novelty

Conservatism/regression bias – we tend to overvalue prior experience and undervalue new information

Default bias – we don’t change established behaviors

Extinction burst – we push against changing our habits even when we know better

Familiarity bias/mere-exposure effect/status quo bias – we prefer familiar experiences

Functional fixedness – we limit an object’s use to how it’s been traditionally used

Mere exposure effect/familiarity principle – we don’t like things when we’re familiar with them

Negativity bias/negativity effect – we remember negative things more than neutral or positive things

Omission bias – we believe doing nothing is better than doing the wrong thing

Semmelweis reflex/Semmelweis effect – we reject new things because they contradict something already established

Status quo bias/tradition appeal – we prefer things the way they have been

Bad Predictions

Anticipatory rationalization – we treat our feelings about the future as if they were reality

Conjunction fallacy – we expect multiple likelihoods are more likely than one likelihood

Disposition effect – we tend to hold onto bad investments and sell good investments

Dunning-Kruger effect – we overestimate our skills when we don’t know much and underestimate skills when we’re highly qualified

End-of-history illusion – we expect we’ll change less in the future than we did up through now

Form function attribution bias – we assume the way something looks is how it’s used

Gambler’s fallacy/Monte Carlo fallacy/fallacy of the maturity of chances – we believe if something is happening more or less frequently than normal, it’ll pivot to the opposite in the future

Hard-easy effect – we think we can do harder things, but not easier things

Impact bias/durability bias/projection bias/self-consistency bias/hedonic adaptation – we overestimate the intensity of future emotional states and underestimate the intensity of past emotional states

Information bias – we keep seeking information even when it doesn’t affect our decisions at all

Nature appeal – we believe natural things are good and unnatural things are bad

Oven logic – we assume adjusting one condition can compensate for changes in another

Prevention bias – we prefer to spend more resources on prevention than detection/response even when they’re the same effectiveness

Process of elimination fallacy/Sherlock Holmes fallacy/arcane explanation – we consider an explanation correct when we rule out other explanations

Pseudocertainty effect – we assume uncertain things are certain

Selection bias – we make statistics with non-random sampling

Self-serving bias – we take credit for positive events and blame others for negative ones

Slippery slope fallacy – we believe that A always leads to B, so seeing A means B will always happen

Subadditivity effect – we tend to make the probability of multiple things together smaller than each of those things individually

Time-saving bias – we underestimate time we can save by going faster from a slow speed, and overestimate time we can save by going faster from a higher speed

Well traveled road effect – we estimate longer times to travel unfamiliar routes than familiar ones

Bad Optimism

Control illusion – we assume we can control events more than we can

Escalation of commitment/irrational escalation – we keep doing things that cause no perceptible positive results

Hot hand fallacy/hot hand phenomenon – we believe a successful result improves the chances of a future successful result

Just-world hypothesis/just-world fallacy – we believe people will get what they morally deserve

Optimism bias/unrealistic optimism/comparative optimism/wishful thinking/valence effect/positive outcome bias – we believe we’re more likely to experience positive results than others

Peltzman effect/risk compensation – we increase risky behavior when we see safety measures

Plan continuation bias – we don’t adapt our plans to changes in realitys

Planning fallacy – we underestimate how much time a task will take

Positivity effect/socioemotional selectivity theory – we prefer to hear positive information

Probability neglect – we ignore likely consequences when we’re uncertain

Pro-innovation bias – we believe a new thing should be adopted universally by society without any adaptations

Restraint bias – we overestimate our ability to control our impulses

Scope neglect – we ignore the size of a problem when considering it

Self-licensing/moral self-licensing/moral licensing/licensing effect – we make immoral choices when we feel confident in ourselves

Validity illusion – we overestimate our ability to accurately analyze data to interpret and predict results

Bad Cynicism

AI effect – we discredit the behavior of an artificial intelligence computer program because we claim it’s not real intelligence

External agency illusion – we assume our satisfaction comes from external factors and not our decisions

Hyperbolic discounting/current moment bias/present bias/dynamic inconsistency – we prioritize immediate benefits over larger long-term benefits

Loss aversion/dread aversion – we spend more effort avoiding painful things than earning the same amount of beneficial things

Not invented here (NIH) syndrome/toothbrush theory – we avoid using things from outside groups

Pessimism bias – we assume negative things are more likely than they really are

Reactance – we feel threatened when certain behaviors might be restricted

Risk compensation – we change our behavior to avoid perceived risks

Zero-risk bias – we try to get rid of all risks on a smaller thing instead of cutting down on overall risk

Zero-sum bias – we assume there’s a winner and a loser even when everyone can win

Bad Hindsight

Choice-supportive bias/post-purchase rationalization – we justify decisions we’ve agreed to and discredit decisions we didn’t take

Confirmation bias/congruence bias/cherry-picking – we look for evidence that confirms what we already think

Endowment effect/divestiture aversion/mere ownership effect – we value something more if we feel it’s ours

Euphoric recall – we remember past experiences more positively than they were

Hindsight bias/knew-it-all-along phenomenon/creeping determinism – we assume we predicted past events more than we really did

Investment loops – we’re more likely to use something later when we invest into something

Effort justification/IKEA effect/labor illusion/processing difficulty effect – we value things much more when we partially create or work with the things that make our consequences

Moral luck – we give moral blame or praise to people not responsible for it

Non-adaptive choice switching/once bitten, twice shy effect/hot stove effect – we avoid previous choices that were ideal because they caused us pain

Outcome bias/defensive attribution hypthesis/consequences appeal/force appeal/fear appeal – we judge decisions by their outcome instead of the quality of the decision itself

Proportionality bias – we assume big events are caused by big things

Retrospective determinism – we assume things will happen again

Rosy retrospection/declinism – we judge the past more positively than the present

Subjective validation/personal validation effect/self-relevance effect – we consider something to be correct if it has personal meaning to us

Sunk cost effect/sunk cost fallacy/commitment escalation/cab driver’s fallacy – we’re slow to pull out of something we’ve already invested in

Socially Under-thinking

Curse of knowledge/curse of expertise – we’re unaware other people don’t have the same knowledge as us

Enemy mine – we assume 2 beliefs that share their dislike for a 3rd one must be compatible

Gender bias – we assume genders automatically can or can’t do certain things

Group attribution error – we assume either one group member represents the entire group, or the group’s decision reflects each individual’s beliefs

Identifiable victim effect/compassion fade – we only help people when we see 1 person’s suffering, but not when it’s many people

Obscurity appeal/Chewbacca defense – we justify things from potentially irrelevant (non-sequitur) or incorrect information, then believe it’s valid because others don’t know that information

Out-group homogeneity effect/out-group homogeneity biasnot – we assume outsiders of our group are more similar to each other than people inside our group

Reverse psychology – people who oppose us can influence us to do what they want by asking the opposite of their desires

Social cryptomnesia – we forget who did things

Stereotype/essentialism/implicit bias – we assume specific things about others define the entirety of who they are

Strawman fallacy/ridicule appeal – we use silly over-simplified versions of others’ beliefs when we disagree with them

Women are wonderful effect – we give more positive attributes to women than men

Bad Social Predictions

Ad hoc – we use speculation as a basis for potential facts

Agent detection/hard work fallacy – we presume someone is always responsible, even for random events

Armchair fallacy – we assume we understand the effort required for others’ creations when we don’t know

Fundamental attribution error/actor-observer bias – we assume people choose and control their situations more than circumstances affecting it

Hawthorne effect/evaluation apprehension – we change our behavior when we know we’re being observed

Intentionality bias – we assume people do things intentionally

Placement bias – we misjudge ourselves compared to others

  • Overconfidence effect/illusory superiority/Lake Wobegon effect/better-than-average effect – we think we’re better at things than others
  • Worse-than-average effect – we assume we’re worse than others at doing things

Pluralistic ignorance – we assume we’re the only person thinking something, even when everyone else is

Transparency illusion – we believe other people know what we’re thinking when they don’t

Bad Social Optimism

Assumed similarity bias – we assume others have more in common than us than they do

Bystander effect – we expect other people around us to act when something must be done

False consensus effect – we overestimate how much other people agree with us

Halo effect/noble edge effect – we assume our positive impression of someone or a group means they’re also good deep-down

In-group favoritism/in-group-out-group bias/in-group bias/intergroup bias/in-group preference – we favor members of our group more than outsiders

Original position fallacy – we prefer a change because we assume we’ll be on the good side of that change

Public goods game – we assume an economic system could exist where we didn’t have to regulate lazy people, cheaters, liars, and thieves

Sexual overperception bias – we assume others are sexually attracted to us when they aren’t

Truth bias – we assume others are speaking the truth

Bad Social Cynicism

Extrinsic incentives bias – we assume others care more about outer incentives than inner incentives (e.g., money over learning skills) than we do

Hostile attribution bias – we assume others have hostile intent even when we don’t know

Human nature fallacy – we assume human nature is inherently bad

Puritanical bias – we assume people do bad things from moral failure without any context

Sexual underperception bias – we assume others aren’t sexually attracted to us when they are

Shared information bias – we spend lots of time retelling people things they already know

Third-person effect – we believe other people are more influenced by mass media than we are

Trait ascription bias – we assume our personalities are flexible and others’ aren’t

Ultimate attribution error – we assume motivations for our groups are good and motivations for groups we’re not in are bad

Bad Social Submission

Abilene effect – we collectively decide for something that’s bad for most or all of us

Authority bias/authority argument/authority appeal – we give weight to an authority figure’s opinion

Availability cascade – we follow what others believe and do, who follow what others believe and do

Bandwagon effect/groupthink – we do and believe things because others are doing it

Ben Franklin effect – we’re more likely to do favors for people we’ve already done favors for

Cheerleader effect/group attractiveness effect – we think individuals are more attractive when they’re in a group

Groupshift – we adapt to more or less risk than the rest of our group

HIPPO problem – we trust the Highest Individually Paid Person’s Opinion

Illusory truth effect/validity effect/reiteration effect – we’ll think a lie is true if we’re repeatedly exposed to it

Nausea argument (ad nauseum) – we believe we’ve dispelled an argument beforehand, so it’s not worth discussing anymore

Observer-expectancy effect/experimenter-expectancy effect/expectancy bias/observer effect/experimenter effect/subject-expectancy effect – the participants of experiments are affected toward researchers’ biases

Pity appeal – we give more grace than we should because we feel sorry for people

Publication bias – we publish scientific papers that validate existing scientific bias

Pygmalion effect – we do what others expect of us

Saying is believing effect – we listen more closely to when messages are adapted to the audience

Survey bias/social desirability bias/courtesy bias/flattery appeal/popularity appeal – we tend to tweak our answers toward whatever is socially acceptable

System justification – we believe any existing system is good to maintain

Wealth appeal/Colbert bump – we give weight to a wealthy or famous person’s opinion

Social Conceit

Assymetric insight illusion – we believe we know others more than they know us

Barnum-Forer effect – we believe generic descriptions of a person apply to us

Bias blind spot/naïve cynicism/naïve realism/objectivity illusion – we see others’ bias, but think we see things objectively

Egocentric bias – we remember things as better than they were

Explanatory depth illusion – we think we can do difficult things more than we can

False uniqueness bias – we believe we and our creations are more unique than they really are

Moral credential effect – we feel we can do immoral things if we’ve done moral things before it

Social comparison bias – we dislike and compete with others we imagine are better than us

Special pleading – we believe general rules for human behavior don’t apply to us

Spotlight effect – we believe others notice us more than they really do

Skewing Antisocially

Automation bias – we assume automated decision-making systems are more unbiased than people

Backfire effect – we intensify our convictions when they’re challenged

Empathy gap/empathy bias – we tend to not feel empathy for others even when we ought to

Inherent nature appeal – we assume something unacceptable is acceptable because the person’s nature is to do it