50 Types of Common Cognitive Biases

1. Fundamental Attribution Error: We judge others on their personality or fundamental character, but we judge ourselves on the situation.
2. Self-Serving Bias: Our failures are situational, but our successes are our responsibility.
3. In-Group Favoritism: We favor people who are in our in-group as opposed to an out-group.
4. Bandwagon Effect: Ideas, fads, and beliefs grow as more people adopt them.
5. Groupthink: Due to a desire for conformity and harmony in the group, we make irrational decisions, often to minimize conflict.
6. Halo Effect: If you see a person as having a positive trait, that positive impression will spill over into their other traits. (This also works for negative traits.)
7. Moral Luck: Better moral standing happens due to a positive outcome; worse moral standing happens due to a negative outcome.
8. False Consensus: We believe more people agree with us than is actually the case.
9. Curse of Knowledge: Once we know something, we assume everyone else knows it, too.
10. Spotlight Effect: We overestimate how much people are paying attention to our behavior and appearance.
11. Availability Heuristic: We rely on immediate examples that come to mind while making judgments.
12. Defensive Attribution: As a witness who secretly fears being vulnerable to a serious mishap, we will blame the victim less if we relate to the victim.
13. Just-World Hypothesis: We tend to believe the world is just; therefore, we assume acts of injustice are deserved.
14. Naïve Realism: We believe that we observe objective reality and that other people are irrational, uninformed, or biased.
15. Naïve Cynicism: We believe that we observe objective reality and that other people have a higher egocentric bias than they actually do in their intentions/actions.
16. Forer Effect (aka Barnum Effect): We easily attribute our personalities to vague statements, even if they can apply to a wide range of people.
17. Dunning-Kruger Effect: The less you know, the more confident you are. The more you know, the less confident you are.
18. Anchoring: We rely heavily on the first piece of information introduced when making decisions.
19. Automation Bias: We rely on automated systems, sometimes trusting too much in the automated correction of actually correct decisions.
20. Google Effect (aka Digital Amnesia): We tend to forget information that’s easily looked up in search engines.
21. Reactance: We do the opposite of what we’re told, especially when we perceive threats to personal freedoms.
22. Confirmation Bias: We tend to find and remember information that confirms our perceptions.
23. Backfire Effect: Disproving evidence sometimes has the unwarranted effect of confirming our beliefs.
24. Third-Person Effect: We believe that others are more affected by mass media consumption than we ourselves are.
25. Belief Bias: We judge an argument’s strength, not by how strongly it supports the conclusion but by how plausible the conclusion is in our own minds.
26. Availability Cascade: Tied to our need for social acceptance, collective beliefs gain more plausibility through public repetition.
27. Declinism: We tend to romanticize the past and view the future negatively, believing that societies/institutions are by and large in decline.
28. Status Quo Bias: We tend to prefer things to stay the same; changes from the baseline are considered to be a loss.
29. Sunk Cost Fallacy (aka Escalation of Commitment): We invest more in things that have cost us something rather than altering our investments, even if we face negative outcomes.
30. Gambler’s Fallacy: We think future possibilities are affected by past events.
31. Zero-Risk Bias: We prefer to reduce small risks to zero, even if we can reduce more risk overall with another option.
32. Framing Effect: We often draw different conclusions from the same information depending on how it’s presented.
33. Stereotyping: We adopt generalized beliefs that members of a group will have certain characteristics, despite not having information about the individual.
34. Outgroup Homogeneity Bias: We perceive out-group members as homogeneous and our own in-groups as more diverse.
35. Authority Bias: We trust and are more often influenced by the opinions of authority figures.
36. Placebo Effect: If we believe a treatment will work, it often will have a small physiological effect.
37. Survivorship Bias: We tend to focus on those things that survived a process and overlook ones that failed.
38. Tachypsychia: Our perceptions of time-shift depend on trauma, drug use, and physical exertion.
39. Law of Triviality (aka “Bike-Shedding”): We give disproportionate weight to trivial issues, often while avoiding more complex issues.
40. Zeigarnik Effect: We remember incomplete tasks more than completed ones.
41. IKEA Effect: We place a higher value on things we partially created ourselves.
42. Ben Franklin Effect: We like doing favors; we are more likely to do another favor for someone if we’ve already done a favor for them than if we had received a favor from that person.
43. Bystander Effect: The more other people are around, the less likely we are to help a victim.
44. Suggestibility: We, especially children, sometimes mistake ideas suggested by a questioner for memories.
45. False Memory: We mistake imagination for real memories.
46. Cryptomnesia: We mistake real memories for imagination.
47. Clustering Illusion: We find patterns and “clusters” in random data.
48. Pessimism Bias: We sometimes overestimate the likelihood of bad outcomes.
49. Optimism Bias: We sometimes are over-optimistic about good outcomes.
50. Blind Spot Bias: We don’t think we have bias, and we see it in others more than ourselves.

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