Category
Cognitive biases
A cognitive bias is a systematic pattern in how people judge, decide or remember, a tendency to depart from what logic, probability or the available evidence would support, in a predictable direction. Random mistakes aren’t biases. A bias is the mistake that keeps pointing the same way.
Fallacies are properties of arguments. Biases are properties of people. You can find a fallacy in a written argument without knowing anything about its author; a bias is a claim about how human minds tend to work.
Entries (11)
- Anchoring effectReplicates robustlyLetting a number you’ve just considered pull your estimate toward it, even when that number tells you little.
- Backfire effectLargely failed to replicateThe claim that correcting a false belief makes people believe it more strongly, which large replications have rarely found.
- Base rate neglectContestedJudging how likely something is from the details of one case while giving too little weight to how common it is in the first place.
- Conjunction fallacyReplicates robustlyJudging that two things happening together is more likely than one of them happening on its own.
- Dunning–Kruger effectContestedThe claim that people who are bad at something overestimate how good they are, because judging the skill takes the skill.
- Framing effectReplicates robustlyMaking a different choice when the same facts are described differently, such as “90% succeed” versus “10% fail”.
- Fundamental attribution errorReplicates robustlyExplaining what someone did by the kind of person they are, while underweighting the situation that produced it.
- Halo effectReplicates robustlyLetting one overall impression of someone color your judgment of their unrelated traits.
- Hindsight biasReplicates robustlyBelieving, once you know how something turned out, that the outcome was more predictable than it really was.
- Planning fallacyContestedForecasting how long a task will take, or what it will cost, from the plan for it rather than from how similar tasks actually went.
- Sunk cost fallacyContestedSticking with something because of what you’ve already spent on it, when only what happens next can make it worth continuing.
Biases are empirical claims
Because a bias is a claim about human psychology, it is established by experiments, and experiments can be wrong. Several famous biases have not held up when other researchers tried to repeat the studies. Every bias on this site carries a replication status:
- Replicates robustly: found repeatedly, by independent researchers, with different methods.
- Contested: real disagreement about whether the effect exists, how big it is, or what causes it.
- Largely failed to replicate: careful attempts to repeat the key findings mostly haven’t found it.
Biases are often shortcuts
Many biases are side effects of mental shortcuts (heuristics) that work well most of the time. Judging quickly from limited information is usually useful, and the bias shows up where the shortcut breaks. Some researchers explain several biases through a single underlying habit, such as “what you see is all there is”.
Knowing about a bias doesn’t switch it off
Most biases operate without awareness, and learning the name of one does little to stop it. What helps more is changing the situation: collecting independent evidence, judging one thing at a time, or deciding what would count as evidence before looking.
Other categories: Formal fallacies · Informal fallacies