# Cognitive Biases: The Complete List With Examples

> Cognitive biases explained: every type of bias in one table, real examples of biases at work, how they relate to heuristics, and how to catch them in time.

Canonical: https://mentarium.io/biases.md

Cognitive Biases · 20 cognitive bias

> **Cognitive biases** are systematic errors in thinking that push judgments and decisions away from what the evidence supports. They are not random mistakes: they show up in predictable directions, in most people, because the mind relies on mental shortcuts (heuristics) that work well in general and fail in specific, recognizable situations.

## Every cognitive bias in the library

[25 Cognitive Biases Examples From Everyday LifeCognitive biases are systematic patterns of error in how people think, judge and decide. They come from mental shortcuts that usually save time but go wrong in predictable ways. Examples include confirmation bias, anchoring, loss aversion and the sunk cost fallacy, and they affect everyone, regardless of intelligence.](https://mentarium.io/biases/cognitive-biases-examples) [Anchoring BiasAnchoring bias is the tendency to rely too heavily on the first piece of information you encounter, usually a number, when making an estimate or decision. Later judgments are adjusted away from that anchor, but not far enough, even when the anchor is obviously irrelevant or random.](https://mentarium.io/biases/anchoring-bias) [Availability HeuristicThe availability heuristic is a mental shortcut in which you judge how common or likely something is by how easily examples come to mind. Recent, vivid, emotional or heavily covered events are easy to recall, so they feel more frequent than they really are, while quiet, common risks feel rarer.](https://mentarium.io/biases/availability-heuristic) [Bandwagon EffectThe bandwagon effect is the tendency to adopt beliefs, behaviors or products because many other people already have. Popularity becomes a stand-in for quality or truth, so ideas spread faster than the evidence behind them, and a choice can feel right simply because the crowd is making it.](https://mentarium.io/biases/bandwagon-effect) [Cognitive DissonanceCognitive dissonance is the mental discomfort you feel when two of your beliefs, or a belief and an action, contradict each other. Leon Festinger described it in 1957. The discomfort pushes you to restore consistency, and the easiest route is often to change the belief or explain the evidence away rather than change the behavior.](https://mentarium.io/biases/cognitive-dissonance) [Confirmation BiasConfirmation bias is the tendency to search for, interpret and remember information in a way that supports what you already believe, while overlooking or discounting evidence against it. It affects how you ask questions, which sources you trust and what you recall later, and it works mostly without you noticing.](https://mentarium.io/biases/confirmation-bias) [Dunning-Kruger EffectThe Dunning-Kruger effect is the finding that people with low skill in a specific area tend to overestimate their performance, partly because the knowledge needed to do a task well is the same knowledge needed to notice mistakes. It describes a pattern in self-assessment, not a measure of general intelligence.](https://mentarium.io/biases/dunning-kruger-effect) [Framing EffectThe framing effect is the tendency to make different choices from the same information depending on how it is presented. A gain frame ("90% survive") and a loss frame ("10% die") describe identical outcomes, yet people prefer safe options when thinking about gains and take risks when thinking about losses.](https://mentarium.io/biases/framing-effect) [Fundamental Attribution ErrorThe fundamental attribution error is the tendency to explain other people's behavior by their character while underestimating the situation they are in. When someone cuts you off in traffic, you think they are a jerk, not that they might be rushing to a hospital. When you do the same thing, you blame the circumstances.](https://mentarium.io/biases/fundamental-attribution-error) [HeuristicsHeuristics are mental shortcuts: simple rules of thumb that let you make judgments and decisions quickly with limited information, time and attention. They usually work well enough, which is why the brain relies on them, but in some situations they produce predictable errors known as cognitive biases.](https://mentarium.io/biases/heuristics) [Hindsight BiasHindsight bias is the tendency, once you know how something turned out, to believe the outcome was more predictable than it really was. It quietly rewrites memory of your earlier uncertainty, producing the 'I knew it all along' feeling and making past decisions look either obviously smart or obviously foolish.](https://mentarium.io/biases/hindsight-bias) [Loss AversionLoss aversion is the tendency to feel a loss more strongly than a gain of the same size, so that losing $100 hurts more than winning $100 pleases. Described in Kahneman and Tversky's prospect theory, it leads people to reject favorable bets, hold on to losing positions and overvalue what they already own.](https://mentarium.io/biases/loss-aversion) [Negativity BiasNegativity bias is the tendency for negative events, information and feelings to have a stronger effect on attention, memory and judgment than positive ones of equal size. One harsh comment outweighs several compliments, one bad experience colors a whole relationship, and threats get noticed faster than opportunities.](https://mentarium.io/biases/negativity-bias) [Overconfidence BiasOverconfidence bias is the tendency to be more sure of your judgments, abilities or predictions than the evidence justifies. Researchers split it into three forms: overestimating your own performance, overplacing yourself relative to others, and overprecision, being too certain your beliefs are accurate. It is one of the most studied and most costly biases.](https://mentarium.io/biases/overconfidence-bias) [Planning FallacyThe planning fallacy is the tendency to underestimate how long a task will take and how much it will cost, even when you know similar tasks have run over before. People plan from the best-case story of their own project and ignore the track record of projects like it.](https://mentarium.io/biases/planning-fallacy) [Self-Serving BiasSelf-serving bias is the tendency to credit your successes to your own skill and effort while blaming your failures on bad luck, other people or circumstances. It protects self-esteem, but it also distorts what you learn from outcomes, because wins teach overconfidence and losses teach nothing.](https://mentarium.io/biases/self-serving-bias) [Status Quo BiasStatus quo bias is the tendency to prefer the current state of affairs simply because it is current. People stick with defaults, existing plans and old habits more often than the merits justify, because change feels like a risk and staying put feels like no decision at all, even when it is one.](https://mentarium.io/biases/status-quo-bias) [Sunk Cost FallacyThe sunk cost fallacy is the tendency to keep investing in a project, plan or relationship because of the time, money or effort already spent, even when the future costs outweigh the future benefits. Past costs cannot be recovered, so a rational choice ignores them and compares only what lies ahead.](https://mentarium.io/biases/sunk-cost-fallacy) [Survivorship BiasSurvivorship bias is the error of drawing conclusions from the people, companies or things that made it through some selection process while ignoring the ones that did not. Because the failures are invisible, the survivors look like the whole story, and their traits get mistaken for the causes of success.](https://mentarium.io/biases/survivorship-bias) [The Halo EffectThe halo effect is the tendency for one positive impression of a person, product or company to spill over into unrelated judgments about it. Someone attractive, confident or successful in one area gets rated as smarter, kinder or more competent in others, without separate evidence for those traits.](https://mentarium.io/biases/halo-effect)

## What are cognitive biases?

Cognitive biases are predictable errors in how people judge and decide. They are not about intelligence or education: smart, well-trained people show them too, often with more confidence. What makes them biases rather than mistakes is that they lean in a consistent direction, so you can name them, anticipate them and build defenses.

A quick test. Suppose you hear that a new product costs $500, then someone asks if $350 sounds fair. Most people will judge $350 more favorably than if they had first heard $200, even though the first number told them nothing about the product’s value. That is [anchoring bias](https://mentarium.io/biases/anchoring-bias), and it works on professionals negotiating real money, not just students in a lab.

Three features show up across nearly all biases:

- **They are automatic.** You don’t decide to be biased. The judgment arrives already tilted.
- **They feel like reasoning.** A biased conclusion comes with reasons attached, which is why it is hard to spot from the inside.
- **They are situational.** The same shortcut that serves you well in one setting misleads you in another.

## Where cognitive biases come from: heuristics

Most biases are the side effect of [heuristics](https://mentarium.io/biases/heuristics): quick rules of thumb the mind uses to make judgments without full calculation. The modern study of this started with Amos Tversky and Daniel Kahneman. Their 1974 paper in _Science_, “Judgment under Uncertainty: Heuristics and Biases,” described three heuristics (representativeness, availability, and anchoring and adjustment) and showed the systematic errors each one produces.

The key insight is that heuristics are usually good. Judging how common something is by how easily you recall examples (the [availability heuristic](https://mentarium.io/biases/availability-heuristic)) works most of the time, because common things tend to be easier to recall. It fails when something is memorable for another reason: a vivid news story, a recent event, a personal scare. Then your sense of “how often” tracks “how memorable” instead.

Kahneman later popularized a two-system description in _Thinking, Fast and Slow_ (2011). System 1 is fast, automatic and intuitive; System 2 is slow, effortful and deliberate. Many biases come from System 1 answering a question, and System 2 accepting the answer without checking. That framing is a simplification (Kahneman described the systems as useful characters, not brain regions), but it explains why slowing down at the right moment helps.

Other researchers, such as Gerd Gigerenzer, have argued that heuristics are often smarter than the bias literature suggests, especially in uncertain, real-world settings. Both views are useful: shortcuts are often right, and you still need to know where they break.

## Types of bias: the six categories

There are many ways to sort biases. Mentarium uses six categories, based on what part of your thinking the bias distorts. The groups overlap a little (confirmation bias touches memory too), but they make the list usable.

| Type of bias | What it distorts | Examples |
|---|---|---|
| Belief and confirmation | What you accept as true | [Confirmation bias](https://mentarium.io/biases/confirmation-bias), [cognitive dissonance](https://mentarium.io/biases/cognitive-dissonance), [halo effect](https://mentarium.io/biases/halo-effect) |
| Memory | How you remember the past | [Hindsight bias](https://mentarium.io/biases/hindsight-bias), [availability heuristic](https://mentarium.io/biases/availability-heuristic) |
| Social | How you judge others and follow the group | [Bandwagon effect](https://mentarium.io/biases/bandwagon-effect), [fundamental attribution error](https://mentarium.io/biases/fundamental-attribution-error) |
| Probability and estimation | How you guess numbers, odds and time | [Anchoring bias](https://mentarium.io/biases/anchoring-bias), [planning fallacy](https://mentarium.io/biases/planning-fallacy), [survivorship bias](https://mentarium.io/biases/survivorship-bias) |
| Self-perception | How you see your own skill and role | [Overconfidence bias](https://mentarium.io/biases/overconfidence-bias), [Dunning-Kruger effect](https://mentarium.io/biases/dunning-kruger-effect), [self-serving bias](https://mentarium.io/biases/self-serving-bias) |
| Decision and choice | How you weigh options, losses and change | [Loss aversion](https://mentarium.io/biases/loss-aversion), [sunk cost fallacy](https://mentarium.io/biases/sunk-cost-fallacy), [status quo bias](https://mentarium.io/biases/status-quo-bias), [framing effect](https://mentarium.io/biases/framing-effect), [negativity bias](https://mentarium.io/biases/negativity-bias) |

### Belief and confirmation biases

These biases protect what you already believe. Confirmation bias makes you seek, notice and remember evidence that supports your view while discounting evidence against it. Cognitive dissonance is the discomfort of holding two conflicting beliefs, and the mind often resolves it by changing the evidence rather than the belief. The halo effect lets one good trait (attractiveness, a famous employer) color your judgment of everything else about a person or product.

### Memory biases

Memory is a reconstruction, not a recording. Hindsight bias makes past events seem more predictable than they were (“I knew it all along”), which quietly teaches you the wrong lessons. The availability heuristic lets recent or vivid memories stand in for how often something really happens.

### Social biases

Humans are social, and our judgments follow the group more than we admit. The bandwagon effect makes an idea more attractive simply because others hold it. The fundamental attribution error makes you explain other people’s behavior by their character (“he’s careless”) while you explain your own by circumstances (“I was rushed”).

### Probability and estimation biases

People are poor intuitive statisticians. Anchoring drags estimates toward whatever number came first. The planning fallacy, described by Kahneman and Tversky in 1979, makes people underestimate how long their own projects will take, even when they know similar projects ran late. Survivorship bias makes you study only the winners and miss the much larger group that tried the same thing and failed.

### Self-perception biases

Most people rate themselves above average on many skills, which can’t be true for everyone. Overconfidence bias shows up as estimates that are too precise and predictions that are too sure. The Dunning-Kruger effect, from a 1999 paper by David Dunning and Justin Kruger, describes how people with low skill in an area tend to overestimate their performance. Self-serving bias credits your successes to skill and your failures to bad luck.

### Decision and choice biases

These are the biases that do the most direct damage to choices. Loss aversion, a central idea in Kahneman and Tversky’s prospect theory (1979), describes how losses tend to feel larger than equal gains. The sunk cost fallacy keeps you investing in something because of what you already spent. Status quo bias makes the current option look better simply because it is current. The framing effect makes the same choice look different depending on whether it is described as a gain or a loss. Negativity bias makes bad news weigh more than equally sized good news.

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## Examples of biases in everyday life

Abstract definitions are easy to agree with and hard to apply. Here are a few hypothetical examples of biases showing up in ordinary decisions. For a longer set, see [cognitive biases examples](https://mentarium.io/biases/cognitive-biases-examples).

- **At work.** Say a manager has decided a new hire is “a star” after a strong first presentation. Months later, the same manager reads mistakes as one-offs and successes as proof. That is the halo effect feeding confirmation bias.
- **With money.** Say an investor bought a stock at $80 and it now trades at $50. They refuse to sell “until it gets back to $80,” although $80 has no bearing on what the stock is worth. Anchoring and loss aversion together.
- **In a relationship.** Say a partner forgets a dinner plan. You decide they are thoughtless (fundamental attribution error) and start recalling every other time they forgot something (availability and confirmation bias), while their good days fade from view (negativity bias).
- **On a project.** Say a team estimates a launch in six weeks because “this one is simpler,” even though their last four launches took three months. The planning fallacy, with overconfidence as a passenger.

Notice that biases rarely come alone. They stack, and each one makes the others feel more reasonable.

## How to beat cognitive biases

Knowing the names of biases helps a little. It helps much more when the knowledge is attached to a process you run at the moment of decision. Research on “debiasing” generally finds that simple awareness is weak, and structured habits are stronger. Here is what tends to work:

1. **Slow down only where it matters.** You can’t audit every judgment. Save the effort for decisions that are costly to undo, high in impact or full of unknowns.
2. **Write your prediction down before the outcome.** This is the most reliable defense against hindsight bias, and it builds a record of how calibrated you are. A [decision journal](https://mentarium.io/decision-making/decision-journal) makes it a habit.
3. **Argue the other side on purpose.** [Steelmanning](https://mentarium.io/mental-models/steelmanning) (stating the strongest version of the opposing view) and [inversion](https://mentarium.io/mental-models/inversion) both force you to look where confirmation bias keeps you from looking.
4. **Use outside numbers.** [Base rates](https://mentarium.io/mental-models/base-rates) are the antidote to anchoring and the planning fallacy: before estimating your case, ask how long or how often for cases like it.
5. **Separate the decision from the people.** Get independent opinions before group discussion, so the first speaker doesn’t anchor the room.
6. **Ask for the graveyard.** For any success story, ask who tried the same thing and failed. That is the [survivorship](https://mentarium.io/mental-models/survivorship) model.

Every bias page in this library ends with the mental model that corrects it, so you can go straight from “I think this is happening” to “here is what to do.”

## The Bias Radar: which biases to watch for which decision

There are too many biases to check every time. The **Bias Radar** narrows the list to the 7 biases that most often distort each kind of decision. Pick the area your decision falls in and run down the list.

| Decision area | The 7 biases on the Bias Radar |
|---|---|
| Career | Status quo bias, loss aversion, sunk cost fallacy, anchoring bias, bandwagon effect, overconfidence bias, availability heuristic |
| Money | Loss aversion, anchoring bias, overconfidence bias, confirmation bias, bandwagon effect, hindsight bias, framing effect |
| Relationships | Halo effect, fundamental attribution error, confirmation bias, negativity bias, sunk cost fallacy, status quo bias, self-serving bias |
| Business | Confirmation bias, planning fallacy, overconfidence bias, survivorship bias, sunk cost fallacy, anchoring bias, bandwagon effect |

How to use it:

1. Name the area (career, money, relationships or business).
2. For each of the seven, ask one question: “Is this one pushing me toward my current favorite?”
3. Mark any that get a yes or a maybe.
4. For each marked bias, apply the correcting model from its page before you decide.

The Bias Radar is the “Stress-test” step of the Mentarium Decision Loop. You can read how it fits the full process in the [decision-making guide](https://mentarium.io/decision-making).

## Cognitive biases vs logical fallacies

People often mix these up. A bias is an error in the process of judgment; a [logical fallacy](https://mentarium.io/critical-thinking/logical-fallacies) is an error in the structure of an argument.

|  | Cognitive bias | Logical fallacy |
|---|---|---|
| Where it lives | In how you form a judgment | In how an argument is built |
| Visible on paper? | Usually not | Usually yes |
| Example | Confirmation bias | Straw man |
| Best defense | Process: write predictions, seek disconfirming evidence | Analysis: check whether the premises support the conclusion |

They interact. Biases make you more likely to accept a fallacious argument when its conclusion is one you like. Both are covered in the [critical thinking](https://mentarium.io/critical-thinking) section.

## The Mentarium take

The most common mistake with cognitive biases is treating them as a list of other people’s flaws. Reading about confirmation bias makes it easy to spot in your coworker and almost impossible to spot in yourself. The research is fairly consistent on this point: people readily see bias in others and underestimate it in themselves.

So we don’t think the goal is to memorize every bias. The goal is to know the seven that matter for the decision in front of you, and to have a habit that catches them. That is why the Bias Radar exists, and why every bias page in this library points to one concrete model that corrects it. A bias you can name but can’t counter is just a word.

Start with the six categories in the table above, pick your decision area on the Bias Radar, and run it once on something real this week. You won’t become unbiased. You will catch more of the errors that cost the most.

## FAQ

### How many cognitive biases are there?

There is no fixed number. Popular lists name anywhere from a few dozen to nearly 200, but many entries overlap or describe the same error in different settings. A working set of about 20 well-studied biases covers most of what distorts everyday decisions.

### What are the main types of bias?

A useful grouping is six types: belief biases (like confirmation bias), memory biases (like hindsight bias), social biases (like the bandwagon effect), probability and estimation biases (like anchoring), self-perception biases (like overconfidence) and decision or choice biases (like loss aversion and the sunk cost fallacy).

### What is the difference between a cognitive bias and a heuristic?

A heuristic is a mental shortcut, such as judging how common something is by how easily examples come to mind. A cognitive bias is the predictable error that shortcut produces when it doesn't fit the situation. The heuristic is the tool; the bias is how it misfires.

### Can you get rid of cognitive biases?

Not entirely. Knowing about a bias helps less than people expect, because biases operate before you notice them. What works better is process: checklists, writing predictions down, asking someone to argue the other side, and using specific mental models that force you to look where the bias keeps you from looking.

### Is cognitive bias the same as a logical fallacy?

No. A logical fallacy is a flaw in the structure of an argument, the kind you can point to on paper. A cognitive bias is a flaw in the process of judgment, often invisible in the final argument. Biases often lead people to accept fallacies that agree with them.

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