Cognitive Biases
Short, linkable explanations of the mind's systematic errors — what they look like, why they happen, and how to counter them. Every entry is backed by replicated evidence.
Most common
Anchoring
The first number you encounter pulls your estimate toward it — even when that number is arbitrary, irrelevant, or obviously too high or too low.
JudgmentConfirmation Bias
The tendency to seek out, favor, and remember information that supports what you already believe — and to overlook or discount whatever cuts against it.
EvidenceFraming Effect
Deciding differently depending on whether the same option is described as a gain or a loss. The facts don't change — the wording does, and the choice follows the wording.
JudgmentFundamental Attribution Error
Explaining other people's behavior by their character while underrating the power of their situation: the driver who cut you off is a jerk, never someone rushing to a hospital.
SocialHalo Effect
Letting one appealing trait — looks, confidence, warmth, success — color everything else you believe about a person, brand, or idea. One bad trait does the same in reverse.
SocialHindsight Bias
Once you know how something turned out, it feels like you saw it coming all along — the outcome quietly rewrites how predictable the past seems.
JudgmentIllusory Truth Effect
The tendency to judge a claim as more likely true simply because you've heard it before — repetition, not evidence, does the persuading.
EvidenceSunk Cost Fallacy
Sticking with a failing course of action because of what you've already put into it — money, years, effort — even though nothing you do next can recover what's spent.
DecisionSurvivorship Bias
Judging a group by its visible successes because the failures never made it into view — when the missing cases carry the real lesson.
EvidenceAll biases by category
Evidence
Belief Bias
Judging an argument by whether you agree with its conclusion instead of whether the logic holds: agreeable conclusions make bad arguments look sound, and vice versa.
EvidenceConfirmation Bias
The tendency to seek out, favor, and remember information that supports what you already believe — and to overlook or discount whatever cuts against it.
EvidenceIllusory Correlation
Seeing a relationship between two things — a group and a behavior, a remedy and a recovery — that the actual numbers don't support.
EvidenceIllusory Truth Effect
The tendency to judge a claim as more likely true simply because you've heard it before — repetition, not evidence, does the persuading.
EvidenceSurvivorship Bias
Judging a group by its visible successes because the failures never made it into view — when the missing cases carry the real lesson.
EvidenceJudgment
Anchoring
The first number you encounter pulls your estimate toward it — even when that number is arbitrary, irrelevant, or obviously too high or too low.
JudgmentBetter-Than-Average Effect
Most people rate themselves above average on everyday abilities — driving, honesty, judging arguments — which is statistically impossible for everyone at once.
JudgmentFraming Effect
Deciding differently depending on whether the same option is described as a gain or a loss. The facts don't change — the wording does, and the choice follows the wording.
JudgmentHindsight Bias
Once you know how something turned out, it feels like you saw it coming all along — the outcome quietly rewrites how predictable the past seems.
JudgmentPlanning Fallacy
Underestimating how long your own substantial projects will take — even when you know that similar projects, including your own past ones, ran late.
JudgmentDecision
Mere Exposure Effect
Liking things more simply because you've encountered them before — familiarity alone, without any new information, breeds preference.
DecisionStatus Quo Bias
Preferring things as they are — sticking with the current plan, provider, or default option even when switching would clearly serve you better.
DecisionSunk Cost Fallacy
Sticking with a failing course of action because of what you've already put into it — money, years, effort — even though nothing you do next can recover what's spent.
DecisionNo biases match your filter.
Social
Bias Blind Spot
Seeing biases clearly in other people while believing your own judgment is the exception — a bias about biases.
SocialCurse of Knowledge
Once you know something, you can't easily imagine not knowing it — so you overestimate how obvious your explanations, hints, and expectations are to everyone else.
SocialFalse Consensus Effect
Overestimating how many people share your opinions, habits, and values — treating your own view as the obvious mainstream one.
SocialFundamental Attribution Error
Explaining other people's behavior by their character while underrating the power of their situation: the driver who cut you off is a jerk, never someone rushing to a hospital.
SocialHalo Effect
Letting one appealing trait — looks, confidence, warmth, success — color everything else you believe about a person, brand, or idea. One bad trait does the same in reverse.
SocialIn-Group Bias
Favoring people who share a group label with you — trusting them more, judging them more kindly, and weighing their arguments more generously than outsiders'.
SocialSelf-Serving Bias
Crediting your successes to skill and your failures to circumstance: the exam you aced proves you're smart, the one you failed was unfair.
Social