100 Cognitive Biases Every Educated Adult Should Know

No.	Item	Definition
1.	Action bias	Preferring action even when inaction would work better.
2.	Actor–observer bias	Explaining one’s behavior situationally but others’ behavior personally.
3.	Ambiguity aversion	Preferring known risks over unknown probabilities.
4.	Anchoring bias	Relying too heavily on the first information received.
5.	Attentional bias	Paying disproportionate attention to certain kinds of information.
6.	Authority bias	Giving undue weight to an authority’s views.
7.	Automation bias	Trusting automated recommendations despite contradictory evidence.
8.	Availability bias	Judging likelihood by how easily examples come to mind.
9.	Bandwagon effect	Adopting beliefs because many others hold them.
10.	Base-rate neglect	Ignoring general frequencies when judging specific cases.
11.	Belief bias	Judging arguments by conclusions rather than logical validity.
12.	Belief perseverance	Maintaining beliefs after their supporting evidence collapses.
13.	Bias blind spot	Recognizing others’ biases more readily than one’s own.
14.	Certainty effect	Giving disproportionate weight to guaranteed outcomes.
15.	Choice-supportive bias	Remembering chosen options more favorably than rejected alternatives.
16.	Clustering illusion	Seeing meaningful patterns in random clusters.
17.	Compromise effect	Favoring middle options over extremes.
18.	Confirmation bias	Favoring information that supports existing beliefs.
19.	Conjunction fallacy	Judging combined events likelier than one component event.
20.	Curse of knowledge	Struggling to imagine what less-informed people understand.
21.	Decoy effect	Changing preferences when an inferior alternative is introduced.
22.	Default effect	Disproportionately choosing the preselected option.
23.	Defensive attribution	Assigning blame partly to protect oneself from vulnerability.
24.	Denomination effect	Spending smaller denominations more readily than equivalent large ones.
25.	Disposition effect	Selling winning investments while holding losing investments.
26.	Distinction bias	Exaggerating differences when comparing options side by side.
27.	Dunning–Kruger effect	Poor performers overestimating their competence.
28.	Egocentric bias	Overestimating one’s contribution to shared activities.
29.	Einstellung effect	Familiar solutions block recognition of better alternatives.
30.	Empathy gap	Underestimating how different emotional states affect behavior.
31.	Endowment effect	Valuing something more because one owns it.
32.	Extrinsic incentive bias	Assuming others respond more to external rewards.
33.	False consensus effect	Overestimating how many others share one’s views.
34.	False polarization	Overestimating differences between opposing groups’ views.
35.	False uniqueness effect	Underestimating how many others share one’s desirable qualities.
36.	Focusing illusion	Overestimating the importance of whatever currently occupies attention.
37.	Framing effect	Deciding differently depending on how information is presented.
38.	Fundamental attribution error	Overemphasizing personality and underestimating circumstances when judging others.
39.	Gambler’s fallacy	Expecting random outcomes to compensate for previous results.
40.	Group attribution error	Assuming group decisions reflect every member’s preferences.
41.	Halo effect	Letting one positive trait influence unrelated judgments.
42.	Hard–easy effect	Overestimating success on hard tasks, underestimating easy ones.
43.	Hindsight bias	Seeing past events as more predictable than they were.
44.	Hostile attribution bias	Interpreting ambiguous behavior as intentionally hostile.
45.	Hostile media effect	Seeing balanced coverage as biased against one’s position.
46.	Hot-hand fallacy	Mistaking chance winning streaks for increased success probability.
47.	Identifiable victim effect	Caring more about named individuals than anonymous groups.
48.	IKEA effect	Overvaluing things one helped create.
49.	Illusion of control	Overestimating personal influence over uncontrollable events.
50.	Illusion of validity	Trusting coherent predictions despite weak supporting evidence.
51.	Illusory correlation	Perceiving a relationship that is absent or exaggerated.
52.	Illusory superiority	Overrating one’s qualities compared with other people’s.
53.	In-group bias	Favoring members of one’s own group.
54.	Intentionality bias	Assuming actions were deliberate rather than accidental.
55.	Just-world bias	Assuming people generally get what they deserve.
56.	Less-is-better effect	Preferring smaller offerings when options are evaluated separately.
57.	Loss aversion	Feeling losses more strongly than equivalent gains.
58.	Mere exposure effect	Liking things more after repeated exposure.
59.	Misinformation effect	Later misleading information alters memories of an event.
60.	Money illusion	Judging money by face value rather than purchasing power.
61.	Mood-congruent memory bias	Recalling information that matches one’s current mood.
62.	Moral credential effect	Using past goodness to excuse later questionable behavior.
63.	Naive realism	Assuming one’s perceptions reflect objective reality.
64.	Negativity bias	Giving negative information more weight than positive information.
65.	Normalcy bias	Underestimating disasters because normal conditions seem likely.
66.	Not-invented-here bias	Rejecting ideas because they originated elsewhere.
67.	Omission bias	Judging harmful inaction less harshly than harmful action.
68.	Optimism bias	Underestimating one’s likelihood of experiencing negative events.
69.	Ostrich effect	Avoiding threatening or unpleasant information.
70.	Out-group homogeneity bias	Seeing outsiders as more alike than group members.
71.	Outcome bias	Judging decisions by results rather than available information.
72.	Overconfidence bias	Overestimating the accuracy of one’s judgments.
73.	Pessimism bias	Overestimating the likelihood of negative outcomes.
74.	Planning fallacy	Underestimating the time and resources a task requires.
75.	Present bias	Giving immediate rewards disproportionate weight over future benefits.
76.	Probability neglect	Focusing on consequences while overlooking their likelihood.
77.	Projection bias	Expecting future preferences to match current preferences.
78.	Pseudocertainty effect	Treating a conditional outcome as guaranteed.
79.	Reactive devaluation	Discounting proposals because they come from an opponent.
80.	Recency effect	Giving recent information greater weight or better recall.
81.	Recency illusion	Assuming newly noticed phenomena only recently began.
82.	Restraint bias	Overestimating one’s ability to resist temptation.
83.	Rhyme-as-reason effect	Finding rhyming statements more credible than nonrhyming equivalents.
84.	Rosy retrospection	Remembering past experiences more positively than they felt.
85.	Salience bias	Overweighting prominent or emotionally striking information.
86.	Scope neglect	Responding insufficiently to changes in a problem’s scale.
87.	Self-serving bias	Claiming successes while blaming failures on external factors.
88.	Shared information bias	Prioritizing commonly known information over members’ unique knowledge.
89.	Status quo bias	Preferring existing arrangements over changes.
90.	Sunk cost fallacy	Continuing because of resources already spent.
91.	Survivorship bias	Drawing conclusions from successes while overlooking failures.
92.	Telescoping effect	Remembering events as closer or farther in time.
93.	Third-person effect	Assuming media messages influence others more than oneself.
94.	Time-saving bias	Misjudging how speed changes affect time saved.
95.	Ultimate attribution error	Explaining outsiders’ failures personally and successes situationally.
96.	Unit bias	Treating a supplied unit as the appropriate amount.
97.	Well-traveled road effect	Estimating familiar routes as shorter than unfamiliar ones.
98.	Worse-than-average effect	Underestimating one’s relative ability, especially on difficult tasks.
99.	Zero-risk bias	Preferring risk elimination over greater overall risk reduction.
100.	Zero-sum bias	Assuming one person’s gain requires another’s loss.