The Cognitive Bias Codex T H E C O G N I T I V E B I A S C O D E X Too Much Information Not Enough Meaning Need To Act Fast What Should We Remember? Availability heuristic Attentional bias Illusory truth effect Mere–exposure effect Context effect Cue–dependent forgetting Mood–congruent memory bias Frequency illusion Baader–Meinhof Phenomenon Empathy gap Omission bias Base rate fallacy We notice things already primed in memory or repeated often Bizarreness effect Humor effect Von Restorff effect Picture superiority effect Self–relevance effect Negativity bias Bizarre, funny, visually striking, or anthropomorphic things stick out more than non-bizarre/unfunny things Anchoring Conservatism Contrast effect Distinction bias Focusing effect Framing effect Money illusion Weber–Fechner law We notice when something has changed Confirmation bias Congruence bias Post–purchase rationalization Choice–supportive bias Selective perception Observer–expectancy effect Experimenter’s bias Observer effect Expectation bias Ostrich effect Subjective validation Continued influence effect Semmelweis reflex We are drawn to details that confirm our own existing beliefs Bias blind spot Naïve cynicism Naïve realism We notice flaws in others more easily than we notice flaws in ourselves Confabulation Clustering illusion Insensitivity to sample size Neglect of probability Anecdotal fallacy Illusion of validity Masked–man fallacy Recency illusion Gambler’s fallacy Hot–hand fallacy Illusory correlation Pareidolia Anthropomorphism We tend to find stories and patterns even when looking at sparse data Group attribution error Ultimate attribution error Stereotyping Essentialism Functional fixedness Moral credential effect Just–world hypothesis Argument from fallacy Authority bias Automation bias Bandwagon effect Placebo effect We fill in characteristics from stereotypes, generalities, and prior histories Out–group homogeneity bias Cross–race effect In–group favoritism Halo effect Cheerleader effect Positivity effect Not invented here Reactive devaluation Well–traveled road effect We imagine things and people we’re familiar with or fond of as better Mental accounting Appeal to probability fallacy Normalcy bias Murphy’s Law Zero sum bias Survivorship bias Subadditivity effect Denomination effect The magical number 7 ± 2 We simplify probabilities and numbers to make them easier to think about Illusion of transparency Curse of knowledge Spotlight effect Extrinsic incentive error Illusion of external agency Illusion of asymmetric insight We think we know what other people are thinking Telescoping effect Rosy retrospection Hindsight bias Outcome bias Moral luck Declinism Impact bias Pessimism bias Planning fallacy Time–saving bias Pro–innovation bias Projection bias Restraint bias Self–consistency bias We project our current mindset and assumptions onto the past and future Overconfidence effect Social desirability bias Third–person effect False consensus effect Hard–easy effect Lake Wobegone effect Dunning–Kruger effect Egocentric bias Optimism bias Forer effect Barnum effect Self–serving bias Actor–observer bias Illusion of control Illusory superiority Fundamental attribution error Defensive attribution hypothesis Trait ascription bias Effort justification Risk compensation Peltzman effect To act, we must be confident we can make an impact and feel what we do is important Hyperbolic discounting Appeal to novelty Identifiable victim effect To stay focused, we favor the immediate, relatable thing in front of us Sunk cost fallacy Irrational escalation Escalation of commitment Generation effect Loss aversion IKEA effect Unit bias Zero–risk bias Disposition effect Pseudocertainty effect Processing difficulty effect Endowment effect Backfire effect To get things done, we tend to complete things we’ve invested time and energy in System justification Reverse psychology Reactance Decoy effect Social comparison effect Status quo bias To avoid mistakes, we aim to preserve autonomy and group status, and avoid irreversible decisions Ambiguity bias Information bias Belief bias Rhyme–as–reason effect Bike–shedding effect Law of Triviality Conjunction fallacy Occam’s razor Less–is–better effect We favor simple–looking options and complete information over complex, ambiguous options Misattribution of memory Source confusion Cryptomnesia False memory Suggestibility Spacing effect We edit and reinforce some memories after the fact Implicit association Implicit stereotypes Stereotypical bias Prejudice Negativity bias Fading affect bias We discard specifics to form generalities Peak–end rule Leveling and sharpening Misinformation effect Serial recall effect List–length effect Duration neglect Modality effect Memory inhibition Primacy effect Recency effect Part–set cueing effect Serial–position effect Suffix effect We reduce events and lists to their key elements Levels–of–processing effect Absent–mindedness Testing effect Next–in–line effect Google effect Tip of the tongue phenomenon We store memories differently based on how they were experienced