The Complete List of 58 Cognitive Biases (with real examples)

Your brain comes with 58 factory defects. Here's the complete inventory, with receipts.

Why You Need This List

Cognitive biases aren't glitches in rare minds. They're standard equipment. Every human arrives pre-loaded with dozens of systematic errors in judgment, evolutionary shortcuts that once kept us alive and now keep us stupid. You can't uninstall them. But you can read the manual.

This is that manual. Fifty-eight biases, organized by where they strike: your decisions, your beliefs, your social life, your memory. One line on what it does. One real example. One link to go deeper.

Start by finding out which ones own you: [take the Bias Blueprint test](/test).

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Decision Biases: When You Choose Poorly

These are the bugs in your choice architecture. They don't just make you wrong, they make you confidently, expensively wrong.

- [Anchoring Bias](/bias/anchoring-bias), First number heard hijacks all subsequent estimates. A $200 "reduced from $500" jacket feels cheap because the anchor stuck. - [Sunk Cost Fallacy](/bias/sunk-cost-fallacy), Throwing good resources after bad to justify past investment. Finishing a terrible movie because you paid for it. - [Framing Effect](/bias/framing-effect), Identical options, different packaging, different choices. "90% survival rate" surgery beats "10% mortality rate." - [Zero-Risk Bias](/bias/zero-risk-bias), Obsessive elimination of tiny risks while ignoring larger ones. Demanding BPA-free bottles while smoking. - [Decoy Effect](/bias/decoy-effect), A strategically bad third option makes the target look irresistible. The $6 medium soda exists to sell $7 larges. - [Endowment Effect](/bias/endowment-effect), Things become more valuable the moment you own them. Mug owners demanding 2-3x market price to sell. - [Hyperbolic Discounting](/bias/hyperbolic-discounting), Immediate rewards crush larger delayed ones. Taking $50 now over $100 in a month. - [IKEA Effect](/bias/ikea-effect), Disproportionate valuation of self-assembled things. Your wobbly bookshelf is "charming," not defective. - [Status Quo Bias](/bias/status-quo-bias), Preference for default options, even when change is clearly superior. Keeping terrible 401(k) allocations for years. - [Paradox of Choice](/bias/paradox-of-choice), More options produce paralysis and dissatisfaction. Walking out of the cereal aisle empty-handed. - [Planning Fallacy](/bias/planning-fallacy), Systematic underestimation of time, costs, and risks. Every software project deadline ever. - [Choice-Supportive Bias](/bias/choice-supportive-bias), Retroactive inflation of chosen options, deflation of rejected ones. "I loved that car" after selling it at a loss. - [Information Bias](/bias/information-bias), Seeking data that feels useful but doesn't change decisions. Reading 47 reviews for a $12 purchase. - [Ambiguity Effect](/bias/ambiguity-effect), Preference for known probabilities over unknown ones. Choosing the job with clear mediocrity over the startup with unclear upside. - [Bike-Shedding Effect](/bias/bike-shedding-effect), Disproportionate focus on trivial, comprehensible issues. Committees debating coffee colors while ignoring pension insolvency. - [Unit Bias](/bias/unit-bias), Consuming one "unit" regardless of appropriate size. Eating the entire bag because it's one bag. - [Loss Aversion](/bias/loss-aversion), Losses hurt roughly twice as much as equivalent gains feel good. Refusing to sell a declining stock to avoid realizing the loss.

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Belief Biases: When You Believe Wrong

These distort what you think is true, how you test truth, and how certain you feel about both.

- [Confirmation Bias](/bias/confirmation-bias), Hunting for confirming evidence, ignoring disconfirming. Only following people who agree on Twitter. - [Availability Heuristic](/bias/availability-heuristic), Judging frequency by ease of recall. Thinking plane crashes are common after one news cycle. - [Survivorship Bias](/bias/survivorship-bias), Studying successes while ignoring invisible failures. Reading billionaire drop-out stories; ignoring millions of broke ones. - [Gambler's Fallacy](/bias/gamblers-fallacy), Believing independent events "balance out." "Red is due" after seven blacks on roulette. - [Base Rate Fallacy](/bias/base-rate-fallacy), Ignoring prior probability in favor of specific information. Assuming a positive test means disease despite 1% base rate. - [Optimism Bias](/bias/optimism-bias), Believing you're less likely to experience negative events than peers. "Divorce happens to other people." - [Ostrich Effect](/bias/ostrich-effect), Avoiding information that might cause psychological discomfort. Not checking bank balances after a spending spree. - [Negativity Bias](/bias/negativity-bias), Negative events and information weigh more heavily. One criticism ruining your week after ten compliments. - [Clustering Illusion](/bias/clustering-illusion), Seeing patterns in random data. Finding "hot hands" in basketball shooting streaks. - [Conjunction Fallacy](/bias/conjunction-fusion), Judging a specific conjunction more probable than a general category. "Linda is a bank teller and feminist" seeming more likely than "Linda is a bank teller." - [Barnum Effect](/bias/barnum-effect), Accepting vague, universal personality descriptions as uniquely accurate. "That's so me" to every horoscope. - [Illusion of Control](/bias/illusion-of-control), Overestimating personal influence over uncontrollable outcomes. Blowing on dice. - [Placebo Effect](/bias/placebo-effect), Experiencing real physiological changes from inert treatments. Sugar pills reducing reported pain. - [Belief Bias](/bias/belief-bias), Judging arguments by conclusion plausibility, not logical validity. Accepting flawed syllogisms with agreeable conclusions. - [Frequency Illusion](/bias/frequency-illusion), Noticing recently learned information everywhere. Seeing your new car model at every intersection. - [Dunning-Kruger Effect](/bias/dunning-kruger-effect), Unskilled individuals overestimate ability; skilled ones underestimate. First-year economics students debating Nobel laureates.

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Social Biases: When Other People Break Your Brain

Humans evolved for tribes, not truth. These biases emerge when other humans enter the equation.

- [Halo Effect](/bias/halo-effect), One positive trait contaminates overall evaluation. Assuming attractive people are also smart and kind. - [Bandwagon Effect](/bias/bandwagon-effect), Adopting beliefs or behaviors because others do. Suddenly caring about Wordle because everyone tweets scores. - [Fundamental Attribution Error](/bias/fundamental-attribution-error), Overemphasizing personality, underemphasizing situation for others' behavior. "He's late because he's lazy" (you're late because of traffic). - [Authority Bias](/bias/authority-bias), Excessive weight to authority figure opinions. Buying supplements because a celebrity doctor endorsed them. - [Groupthink](/bias/groupthink), Conformity pressure overriding critical evaluation in cohesive groups. The Bay of Pigs invasion planning. - [False Consensus Effect](/bias/false-consensus-effect), Overestimating how much others share your views. "Everyone thinks that movie was overrated." - [In-Group Bias](/bias/in-group-bias), Favoring members of your own group. Hiring the alum from your mediocre college over the qualified outsider. - [Spotlight Effect](/bias/spotlight-effect), Overestimating how much others notice your appearance/behavior. Changing shirts three times; no one remembers what you wore. - [Ben Franklin Effect](/bias/ben-franklin-effect), Doing favors for someone increases your liking of them. Helping a colleague you disliked, then deciding they're "not so bad." - [Bystander Effect](/bias/bystander-effect), Reduced helping likelihood with more witnesses. Kitty Genovese; 38 bystanders, delayed emergency call. - [Curse of Knowledge](/bias/curse-of-knowledge), Once you know something, you can't imagine not knowing it. Tech support explaining obvious steps with increasing frustration. - [Self-Serving Bias](/bias/self-serving-bias), Attributing success to yourself, failure to circumstances. "I earned that promotion; I was unlucky on that project." - [Just-World Hypothesis](/bias/just-world-hypothesis), Believing the world is fair, so victims must have done something wrong. "She was probably asking for it." - [Identifiable Victim Effect](/bias/identifiable-victim-effect), Greater emotional response to single, specific victims than statistical masses. $700,000 raised for one child; indifference to thousands starving.

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Memory Biases: When Your Past Is Fiction

Memory isn't playback. It's reconstruction, and your brain takes creative liberties.

- [Hindsight Bias](/bias/hindsight-bias), "I knew it all along" after outcomes are known. Claiming you predicted the 2008 crash. - [Peak-End Rule](/bias/peak-end-rule), Memories dominated by peak intensity and final moments, not duration. A vacation ruined by a terrible final day. - [Google Effect (Digital Amnesia)](/bias/google-effect-digital-amnesia), Reduced memory for information easily found online. Forgetting your sister's birthday because Facebook reminds you. - [Misinformation Effect](/bias/misinformation-effect), Post-event information contaminates original memory. Witnesses incorporating leading questions into testimony. - [Zeigarnik Effect](/bias/zeigarnik-effect), Better memory for interrupted or incomplete tasks. The song lyric you can't finish playing on loop in your head. - [Recency Bias](/bias/recency-bias), Overweighting recent events in judgment. Firing the coach after three losses, forgetting the championship. - [Primacy Effect](/bias/primacy-effect), Better recall of first items in a sequence. Remembering the first candidate in interviews most vividly. - [Rosy Retrospection](/bias/rosy-retrospection), Past events recalled more positively than experienced. "The 90s were so much better" (they weren't). - [Cryptomnesia](/bias/cryptomnesia), Forgetting the source of an idea, believing you originated it. George Harrison's "My Sweet Lord" / "He's So Fine." - [Context-Dependent Memory](/bias/context-dependent-memory), Recall improved when in original learning context. Remembering everything when back in the exam room. - [Spacing Effect](/bias/spacing-effect), Better retention with distributed versus massed practice. Cramming fails; same hours spread across weeks works.

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What Now?

You've just scanned 58 ways your brain systematically deceives you. Reading them once won't fix anything. Recognition is slow; habituation is slower. The biases that cost you most are the ones you still think you don't have.

The fastest path to seeing your own machinery: [take the Bias Blueprint test](/test). It surfaces your personal vulnerability profile, which biases dominate your specific patterns of error. Then come back to the ones that matter. The list will wait. Your unchecked biases won't.