Cognitive Biases List with Examples
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A bias, in this library, is not a fallacy with a Latin name. It is a tug on judgement: what you already believe, what you can remember, the first number you heard, the way a fact is worded. The list below is every card filed as a cognitive bias. Fallacies live on the other list. Kahneman’s own sentences, the ones this library can cite, are on his topic hub, not repeated here as if the bias cards were quotations.
Each entry shows the definition and the everyday example already on the card. Open the card for the reply, the two practice questions, and the comparison it is often mixed up with. Nothing on this page is a rate, a percentage, or a claim about how common the bias is. The cards do not contain those figures, so this list does not invent them.
Confirmation bias
Confirmation bias is the tendency to search for, remember, and accept what supports a view you already like, and to skim past what would hurt it. It is not a claim that every belief is stubborn. It is a pattern in how attention is spent.
You favour a view about study habits. You bookmark articles that agree and close the ones that do not, then feel well informed.
Availability bias
Availability bias judges how common something is by how easily examples come to mind. Vivid, recent, or personal cases feel frequent. A dull record of ordinary cases is harder to recall and gets underweighted.
You remember dramatic train delays and start to believe delays are very common, though the published record shows they are rare.
Anchoring
Anchoring is the pull of the first number or fact you meet. Later figures are judged against it, even when the first figure was arbitrary or a deliberate high price. A relevant comparison breaks the pull.
A shop shows a kettle at £80, then a “reduced” one at £45. The £45 feels like a bargain even though similar kettles sell for £30.
Sunk cost
Sunk-cost thinking lets a past loss decide a future choice. Money or time already spent is gone whether you continue or stop. The live question is which option is better from now on.
You keep attending a class you dislike because you have paid the fee, even though a different class would serve you better and the fee will not be refunded either way.
Survivorship bias
Survivorship bias looks at the cases you can still see and forgets the ones that disappeared. The successes are interviewed. The attempts that failed are quiet. A rate needs both.
A company celebrates founders who dropped out of college and became famous, and concludes that dropping out helps. It does not look at dropouts who did not become famous.
Framing
Framing changes a decision by changing the wording of the same facts. “90% survival” and “10% mortality” describe one risk. People often treat them as different risks because one wording highlights the gain and the other the loss.
The same operation is described to one group as “90% survival” and to another as “10% mortality.” The first group is more willing to choose it.
Halo effect
The halo effect lets one striking trait colour judgements that the trait does not speak to. Warmth, beauty, confidence, or a famous employer spills onto unrelated questions such as accuracy or honesty.
A tutor who is warm and funny is assumed, without further evidence, to be accurate about a technical subject outside their field.
Gambler’s fallacy
The gambler’s fallacy treats independent events as if they owed you a correction. After a run of one result, the other result feels “due.” If the events are independent, the run does not change the next chance.
After three rainy match days, a fan says the next match “is due” to be dry, as if the weather kept a balance sheet.
Overconfidence
Overconfidence is certainty that outruns the evidence, common when someone has just met a subject and cannot yet see its difficulties. Specialists often hedge because they can see the ways a claim fails. High confidence is not high competence.
You feel sure about a topic you have only just met, while a specialist hedges. A later test shows you knew little. Confidence rose faster than skill.
Selection bias
Selection bias distorts a result because the people or cases you reached are not a fair stand-in for the group you want to talk about. The flaw is in who got into the sample, not only in how you do the arithmetic afterwards.
A survey about reading habits is posted only in a book-club forum, then used as a picture of “people in general.” Book-club members are already heavy readers.
Hindsight bias
Hindsight bias makes a past event feel as if it was obviously going to happen, once you know that it did. The feeling of “I knew it” arrives after the result and rewrites how uncertain the situation was.
After a match, a supporter says the defeat was obvious from the team sheet. Before kickoff the same supporter expected a win.
Fundamental attribution error
The fundamental attribution error explains other people’s behaviour by their character, and underweights the situation. Your own similar behaviour is easier to explain by the circumstances. The bias is the uneven use of those two explanations.
A colleague misses a deadline and is called careless. When you miss one, the explanation is the outage, the illness, or the unclear brief.
Planning fallacy
The planning fallacy is underestimating the time, cost, or difficulty of a task, especially one you are inside. You picture the smooth path and leave out delays that, on similar tasks, usually appear. Hope is not a base rate.
You plan to finish the essay in an evening because that is how the writing feels at the desk. Your last four essays each took three evenings.
Base-rate neglect
Base-rate neglect grabs a vivid likelihood and ignores how common the thing was to begin with. A test can be quite accurate and still be wrong most of the time it raises an alarm, if the condition is rare.
A test is 95% accurate and flags a rare condition that affects 1 in 1,000. Most of the alarms will still be false, because the 5% error falls on a much larger healthy group.
Status-quo bias
Status-quo bias prefers the current arrangement because it is current, and treats a change as a loss even when the change is the better expected option. There can be real costs to changing. The bias is counting “it is already so” as a reason beyond those costs.
A timetable wastes an hour a week. A better one is costed, including the nuisance of switching, and still wins. The reply is, “But this is the timetable we have.”