# 25 Cognitive Biases Examples From Everyday Life > 25 cognitive biases examples from everyday life: money, work, relationships and the news. A plain definition and a real-world example for each one. Canonical: https://mentarium.io/biases/cognitive-biases-examples.md Cognitive bias 10 min read By [Nemo](https://mentarium.io/about) Updated October 30, 2026 > **Cognitive 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. - **Category**: Cognitive biases (overview and examples) - **Origin**: Tversky & Kahneman's heuristics and biases research, 1970s onward - **Best used for**: Recognizing biases in ordinary decisions before they cost you - **Related**: Heuristics, confirmation bias, anchoring bias, sunk cost fallacy ## What are cognitive biases, in plain words? Cognitive biases are predictable mistakes your mind makes when it takes shortcuts. They are not random errors: they push your judgment in a consistent direction, which is why psychologists can study them and why you can learn to catch them. Most biases come from [heuristics](https://mentarium.io/biases/heuristics), the rules of thumb your brain uses to decide fast. A shortcut that works 90% of the time will fail the other 10% in the same way each time. That repeated failure is a bias. Below are 25 cognitive biases examples, grouped by where you’re most likely to meet them: money, work, relationships, and beliefs and memory. Each has a one-line definition and an everyday example. The examples are hypothetical but typical; the research mentioned is real. Where Mentarium has a full page on the bias, it’s linked. ## Money and shopping biases ### 1. Anchoring bias **Definition:** the first number you see pulls your estimate toward it, even when it’s irrelevant. **Example:** A jacket is marked “was $300, now $150.” The $300 makes $150 feel like a deal, though you’d never have paid $150 for it on a plain tag. Tversky and Kahneman showed in 1974 that even a number from a spun wheel shifts estimates. Full page: [anchoring bias](https://mentarium.io/biases/anchoring-bias). ### 2. Loss aversion **Definition:** losses feel stronger than gains of the same size, so you work harder to avoid losing than to win. **Example:** You won’t sell a stock at a loss, even though you’d never buy it today, because selling makes the loss “real.” Kahneman and Tversky built this into prospect theory (1979); common estimates put losses at roughly twice the psychological weight of equal gains. Full page: [loss aversion](https://mentarium.io/biases/loss-aversion). ### 3. Sunk cost fallacy **Definition:** continuing something because of what you’ve already put in, rather than what you’ll get out of it from here. **Example:** You sit through a bad movie because the ticket cost $18, or keep paying for a gym you never use because you bought the annual plan. The money is gone either way; only your next two hours are still up for grabs. Hal Arkes and Catherine Blumer documented the effect in 1985. Full page: [sunk cost fallacy](https://mentarium.io/biases/sunk-cost-fallacy). ### 4. Framing effect **Definition:** the same facts lead to different choices depending on how they’re worded. **Example:** Ground beef labeled “80% lean” sells better than the same beef labeled “20% fat.” In Tversky and Kahneman’s 1981 study, people picked differently between identical medical programs described in terms of lives saved versus lives lost. Full page: [framing effect](https://mentarium.io/biases/framing-effect). ### 5. Decoy effect **Definition:** adding a third, clearly worse option makes one of the original two look better. **Example:** A cinema sells small popcorn for $4, medium for $7.50 and large for $8. Nobody wants the medium; it exists to make the large look like a steal. Joel Huber, John Payne and Christopher Puto described this “asymmetric dominance” effect in 1982. ### 6. Endowment effect **Definition:** you value something more just because you own it. **Example:** You list your used bike for $400, but you’d never pay more than $250 for the same bike from a stranger. In experiments by Daniel Kahneman, Jack Knetsch and Richard Thaler (1990), people given a coffee mug asked for much more to sell it than others were willing to pay to buy one. ### 7. Gambler’s fallacy **Definition:** believing that a random event is “due” because it hasn’t happened in a while. **Example:** A roulette wheel lands on black six times in a row, so you bet big on red. The wheel has no memory; each spin has the same odds. The same thinking leads parents with three boys to feel a girl is “due.” ## Work and career biases ### 8. Planning fallacy **Definition:** underestimating how long a task will take, even when you know similar tasks ran late before. **Example:** You promise the report by Friday, as you did last month, when it arrived the following Wednesday. Kahneman and Tversky named the planning fallacy in 1979, and Roger Buehler, Dale Griffin and Michael Ross (1994) found students routinely finished their theses later than even their “worst case” predictions. Full page: [planning fallacy](https://mentarium.io/biases/planning-fallacy). ### 9. Overconfidence bias **Definition:** being more sure of your judgments, skills or forecasts than your track record supports. **Example:** You give a project estimate as “six weeks,” with no range, and you’d bet on it. When people are asked for ranges they’re 90% sure of, the truth falls outside far more than 10% of the time. Full page: [overconfidence bias](https://mentarium.io/biases/overconfidence-bias). ### 10. Dunning-Kruger effect **Definition:** people with low skill in an area tend to overestimate their performance the most. **Example:** After two weeks of tutorials, a new coder feels ready to rewrite the company’s backend; the senior engineer, who knows what can go wrong, is far more cautious. Justin Kruger and David Dunning published the original study in 1999. Full page: [Dunning-Kruger effect](https://mentarium.io/biases/dunning-kruger-effect). ### 11. Status quo bias **Definition:** preferring things to stay as they are, even when a change would be better. **Example:** You stay on the default retirement plan and the same bank for a decade, never comparing fees, because switching feels like effort and risk. William Samuelson and Richard Zeckhauser named the bias in 1988. Full page: [status quo bias](https://mentarium.io/biases/status-quo-bias). ### 12. Self-serving bias **Definition:** crediting your successes to yourself and blaming your failures on outside factors. **Example:** When your pitch lands, it’s because you prepared well. When it flops, the client “wasn’t ready” or the timing was bad. Same person, two very different explanations. Full page: [self-serving bias](https://mentarium.io/biases/self-serving-bias). ### 13. Curse of knowledge **Definition:** once you know something, it’s hard to imagine not knowing it, so you explain it badly. **Example:** An expert writes onboarding docs full of jargon and skipped steps that feel obvious to them. In a 1990 study by Elizabeth Newton, people tapped out well-known songs and predicted listeners would name about half; listeners named about 3 out of 120. ### 14. IKEA effect **Definition:** valuing things more because you built them yourself. **Example:** A team defends an internal tool they built over a better, cheaper product on the market, partly because they made it. Michael Norton, Daniel Mochon and Dan Ariely (2012) found people valued furniture and origami they had assembled more than identical items made by others. The Mentarium Field Guide 60 mental models, organized by the decision in front of you Each model on one or two pages: when to use it, the questions to ask, an example and the trap. Plus the 25 biases that break decisions and 12 ready Model Stacks. [See Field Guide · $14](https://mentarium.io/shop/field-guide) ## Relationship and social biases ### 15. Halo effect **Definition:** one positive trait colors your judgment of everything else about a person. **Example:** You assume a confident, good-looking candidate is also competent and honest, and you ask fewer hard questions. Edward Thorndike described the effect in 1920 in ratings of soldiers by their officers. Full page: [halo effect](https://mentarium.io/biases/halo-effect). ### 16. Fundamental attribution error **Definition:** explaining other people’s behavior by their character while explaining your own by circumstances. **Example:** The driver who cut you off is a jerk. When you cut someone off, it’s because you were late for a school pickup. Lee Ross named the error in 1977. Full page: [fundamental attribution error](https://mentarium.io/biases/fundamental-attribution-error). ### 17. Spotlight effect **Definition:** overestimating how much other people notice you, your mistakes and your appearance. **Example:** You spend a whole party worried about the stain on your shirt; almost nobody saw it. Thomas Gilovich, Victoria Medvec and Kenneth Savitsky (2000) had students wear an embarrassing T-shirt into a room, and far fewer people noticed it than the wearers predicted. ### 18. Bandwagon effect **Definition:** adopting a belief or behavior because many other people have. **Example:** You buy a coin, a sneaker or a diet because everyone on your feed seems to be doing it, not because you checked whether it fits you. Solomon Asch’s conformity experiments in the 1950s showed how strongly a group can pull an individual’s judgment. Full page: [bandwagon effect](https://mentarium.io/biases/bandwagon-effect). ### 19. Negativity bias **Definition:** bad things weigh more on your mind than good things of the same size. **Example:** Your partner says ten kind things this week and one sharp thing, and the sharp thing is what you replay at night. Roy Baumeister and colleagues reviewed the evidence in a 2001 paper titled “Bad Is Stronger Than Good.” Full page: [negativity bias](https://mentarium.io/biases/negativity-bias). ## Belief, news and memory biases ### 20. Confirmation bias **Definition:** looking for, favoring and remembering information that supports what you already believe. **Example:** You think a coworker is lazy, so you notice every early exit and none of the late nights. Peter Wason’s 2-4-6 task (1960) showed people testing only the cases that could confirm their guess. Full page: [confirmation bias](https://mentarium.io/biases/confirmation-bias). ### 21. Availability heuristic **Definition:** judging how likely something is by how easily examples come to mind. **Example:** After a week of plane crash coverage, flying feels more dangerous than the drive to the airport, though by most measures the drive carries more risk per trip. Tversky and Kahneman described the heuristic in 1973. Full page: [availability heuristic](https://mentarium.io/biases/availability-heuristic). ### 22. Hindsight bias **Definition:** after something happens, believing you knew it would happen all along. **Example:** After a startup fails, everyone “saw it coming,” though nobody said so beforehand. Baruch Fischhoff showed in 1975 that knowing an outcome changes how predictable people think it was. Full page: [hindsight bias](https://mentarium.io/biases/hindsight-bias). ### 23. Survivorship bias **Definition:** drawing conclusions only from the winners that remain visible and ignoring the failures that disappeared. **Example:** “Bill Gates and Mark Zuckerberg dropped out, so college is overrated” ignores the far larger number of dropouts who didn’t build giant companies. The classic story is Abraham Wald’s World War II analysis of where to armor returning bombers. Full page: [survivorship bias](https://mentarium.io/biases/survivorship-bias). ### 24. Cognitive dissonance **Definition:** the discomfort of holding two clashing beliefs, or acting against a belief, which pushes you to justify yourself. **Example:** You spent $2,000 on a watch while saving for a house, and suddenly you’re very sure watches are a smart investment. Strictly it’s a feeling rather than a bias, but the way people resolve it produces biased judgment. Leon Festinger introduced the theory in 1957. Full page: [cognitive dissonance](https://mentarium.io/biases/cognitive-dissonance). ### 25. Optimism bias **Definition:** believing you’re less likely than other people to suffer bad events and more likely to enjoy good ones. **Example:** You know most new restaurants struggle, but you’re sure yours will be the exception, so you skip the savings buffer. Neil Weinstein documented “unrealistic optimism” about future life events in 1980. ## Which biases hit which decisions? The same bias doesn’t matter equally everywhere. Our Bias Radar lists the seven biases that most often distort each kind of decision: | Decision type | 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 | Before a big decision, pick the row that fits and ask, for each bias: “Is this one active here?” Seven questions take five minutes. ## How to catch biases in your own decisions You catch biases mostly through process, not willpower, because biases feel like clear thinking from the inside. Four habits do most of the work: 1. **Invert the question.** Ask what would have to be true for you to be wrong, and look for that first. [Inversion](https://mentarium.io/mental-models/inversion) defuses confirmation bias, overconfidence and optimism bias in one move. 2. **Start from the base rate.** How often does this kind of thing usually work out? [Base rates](https://mentarium.io/mental-models/base-rates) counter anchoring, the availability heuristic and the planning fallacy. 3. **Write predictions down.** A dated prediction with a confidence % is the only reliable defense against hindsight bias and self-serving stories. A [decision journal](https://mentarium.io/decision-making/decision-journal) makes this a habit. 4. **Match effort to stakes.** You don’t need a bias check for lunch. Use the [Decision Weight Score](https://mentarium.io/tools/decision-weight-score) to decide which choices deserve the full treatment. For a closer look at the shortcuts behind these errors, read [heuristics](https://mentarium.io/biases/heuristics). For the tools that correct them, browse the [mental models library](https://mentarium.io/mental-models) or the full [biases hub](https://mentarium.io/biases). ## The Mentarium take Lists of cognitive biases are fun to read and almost useless on their own. Knowing that anchoring exists will not stop the next “was $300” tag from working on you. Studies on bias awareness suggest that simply knowing a bias’s name helps only a little. What helps is attaching a habit to the moments that matter. That is why we group biases by decision type rather than alphabetically: you don’t need to remember 25 biases, you need to remember the seven on the Bias Radar row for the decision in front of you. And you need a process that checks for them at the right time. In the Mentarium Decision Loop (Frame → Map → Stress-test → Decide → Review), that time is the Stress-test step, when you run the Bias Radar against your favorite option, not the ones you already dislike. One more honest point: many popular bias lists include effects with weak or disputed evidence, and some “biases” are reasonable strategies in the right setting. We’ve kept this list to well-studied effects, and we’d rather you know 10 of them well enough to catch them in your own head than recognize 100 of them in other people’s. **Fixed by** [Inversion](https://mentarium.io/mental-models/inversion) ## FAQ ### What are the most common cognitive biases? Some of the most widely studied are confirmation bias, anchoring bias, the availability heuristic, loss aversion, overconfidence bias, the sunk cost fallacy, hindsight bias and the halo effect. They show up across money, work and relationship decisions. ### What is an example of a cognitive bias in everyday life? Keeping a gym membership you never use because you already paid the annual fee is the sunk cost fallacy. Thinking a $150 jacket is a bargain because the tag says it was $300 is anchoring. Both happen without you noticing. ### How many cognitive biases are there? There is no fixed number. Popular lists name well over a hundred, but many overlap or describe the same underlying effect in different settings, and some have weaker evidence than others. A few dozen core biases explain most everyday errors. ### Are cognitive biases the same as logical fallacies? No. A cognitive bias is a pattern in how your mind processes information, usually automatic. A logical fallacy is an error in the structure of an argument. Biases can lead you to accept fallacies, but they are studied separately. ### Can you avoid cognitive biases completely? No. They are built into how human judgment works, and knowing about them only helps a little. What does help is process: writing predictions down, considering the opposite, using base rates and asking someone else to check high-stakes decisions. ### Do smart people have fewer cognitive biases? Not reliably. Intelligence helps on some reasoning tasks, but smart people are also better at building arguments for what they already believe. Expertise reduces some biases inside a person's field and leaves others untouched. ## Related models & biases [Cognitive bias Heuristics Heuristics 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) [Cognitive bias Confirmation Bias Confirmation 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) [Cognitive bias Anchoring Bias Anchoring 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) [Cognitive bias Sunk Cost Fallacy The 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) [Mental model Inversion Inversion is a mental model that approaches a problem from the opposite end: instead of asking how to succeed, you ask what would guarantee failure, then avoid those things. It also means testing a belief by asking what would have to be true for the opposite to be right. Charlie Munger made it famous in business.](https://mentarium.io/mental-models/inversion) Mentarium Decision Coach · free Use this with your AI Connect the free Decision Coach to Claude or ChatGPT and it walks you through the Decision Loop, picks the right Model Stack and runs the Bias Radar on your reasoning. [Connect it free](https://mentarium.io/coach) Mentarium Decision Coach · free Use this with your AI [Connect it free](https://mentarium.io/coach)