Below is the complete table of all 116 entries currently listed by The Decision Lab. Their page describes these collectively as cognitive biases, although the collection also contains heuristics, psychological effects, fallacies, and related behavioral concepts. thedecisionlab.com

The definitions and examples below are concise explanations written in plain English, rather than copied from the site.

# Bias / Heuristic / Effect Definition Simple Example
1 AI Literacy Gap The gap between people’s confidence in using AI and their actual understanding of how it works and its limitations. Someone confidently trusts an AI-generated legal answer without realizing the AI can hallucinate facts.
2 Accountability Diffusion in AI Responsibility becomes unclear when decisions are shared between humans, organizations, and AI systems. A bad loan decision is blamed on “the algorithm,” while nobody takes responsibility.
3 Action Bias The tendency to prefer doing something over doing nothing, even when inaction may be better. An investor trades during every market dip instead of patiently holding.
4 Affect Heuristic Using current feelings as a shortcut for judging risks and benefits. You like a company’s charismatic CEO, so you assume its stock is a good investment.
5 Ambiguity Effect Preferring options with known probabilities over options where the probabilities are uncertain. You choose an investment with a known 6% expected return rather than an unfamiliar investment whose odds are unclear.
6 Anchoring Bias Relying too heavily on the first number or information encountered. A house listed at $1 million makes $900,000 seem cheap, even if comparable homes are worth $800,000.
7 Attentional Bias Paying disproportionate attention to certain information while ignoring other relevant information. After hearing about layoffs, you notice every layoff story and overlook companies hiring workers.
8 Authority Bias Giving excessive weight to the opinion of an authority figure. You accept an investment recommendation simply because a famous economist made it.
9 Automation Bias Over-relying on automated systems and accepting their output without adequate verification. GPS tells you to drive onto a closed road, and you follow it without questioning it.
10 Availability Heuristic Judging probability by how easily examples come to mind. After seeing several plane-crash stories, you think flying is more dangerous than driving.
11 Bandwagon Effect Adopting beliefs or behaviors because many other people are doing so. You buy a popular stock mainly because everyone online is buying it.
12 Barnum Effect Accepting vague personality descriptions as uniquely applicable to oneself. A horoscope says, “You sometimes doubt yourself but want others to respect you,” and it feels personally accurate.
13 Base Rate Fallacy Ignoring general statistical probabilities in favor of specific or vivid information. Someone seems quiet and analytical, so you assume they’re a librarian, ignoring that there are far more salespeople than librarians.
14 Belief Perseverance / Backfire Effect Holding onto a belief despite strong evidence that contradicts it. Evidence shows a health claim is false, but a believer becomes even more committed to it.
15 Benjamin Franklin Effect Becoming more favorable toward someone after doing that person a favor. A coworker lends you a book and subsequently feels warmer toward you.
16 Bikeshedding Spending excessive time discussing trivial issues while neglecting more important, complicated ones. A committee approves a $10 million project quickly but debates the office coffee machine for an hour.
17 Bottom-Dollar Effect Feeling less satisfied with purchases when spending the last of your available money. A $50 dinner feels enjoyable when you have $5,000 in the bank but painful when you only have $60.
18 Bounded Rationality Making satisfactory rather than perfectly optimal decisions because time, information, and mental capacity are limited. You choose a reasonably good insurance policy instead of comparing all 100 available plans.
19 Bundling Bias Treating individual items in a bundle as less valuable or less important than separately purchased items. You are more likely to skip a concert when the ticket was part of a season package than when you bought it individually.
20 Bye-Now Effect Certain sound associations, such as words resembling “buy,” can subtly influence purchasing behavior. Hearing “bye-bye” in an advertisement may unconsciously increase purchase-related associations.
21 Cashless Effect Spending tends to feel less painful when payment is made electronically rather than with physical cash. Spending $100 with a credit card feels easier than handing over five $20 bills.
22 Category Size Bias Misjudging probabilities because we focus on the apparent size of categories rather than the number of opportunities within them. Someone thinks a large casino gives them a better chance of winning simply because it has more winners, overlooking that it also has more gamblers.
23 Choice Overload Having too many options can make choosing harder and reduce satisfaction. You leave a store without buying jam because there are 40 varieties to choose from.
24 Cognitive Dissonance Psychological discomfort caused by holding conflicting beliefs or behaving inconsistently with one’s beliefs. A smoker who knows smoking is dangerous tells himself, “My grandfather smoked and lived to 90.”
25 Commitment Bias Continuing to support a previous decision because you have already committed to it. A manager keeps defending a failing project because it was originally their idea.
26 Confirmation Bias Seeking, interpreting, and remembering information that supports existing beliefs. A bullish Tesla investor reads positive Tesla news while dismissing negative reports.
27 Decision Fatigue Decision quality deteriorates after making many decisions. After a long day of work, you impulsively order junk food rather than preparing dinner.
28 Declinism Believing society or the world is getting worse while idealizing the past. Someone says, “People had better morals 40 years ago,” while forgetting the problems of that era.
29 Decoy Effect Adding an inferior third option changes preferences between two existing options. Small coffee: $4, medium: $6.50, large: $7. The expensive medium makes the large look like a bargain.
30 Delegation Creep Gradually handing more decisions over to AI or automated systems than originally intended. You initially use AI to summarize emails, then gradually allow it to decide which messages deserve responses.
31 Disposition Effect Investors tend to sell winning investments too early and hold losing investments too long. You sell a stock up 10% to lock in profit but keep a stock down 40% hoping it will recover.
32 Distinction Bias Differences between options seem larger when compared side-by-side than when experienced separately. Two TVs look dramatically different in the store, but either would look excellent at home.
33 Dunning–Kruger Effect People with limited skill in an area may overestimate their competence because they lack the knowledge needed to recognize their mistakes. A beginner investor believes investing is easy after making money on two trades.
34 Einstellung Effect Familiar solutions prevent us from seeing better solutions. You keep solving a database problem using the method you’ve always used even though a simpler method exists.
35 Empathy Gap Underestimating how strongly emotional or physical states influence ourselves or others. When full, you underestimate how tempting junk food will be when you’re hungry.
36 Endowment Effect Valuing something more simply because you own it. You wouldn’t pay more than $50 for a watch, but after owning it you refuse to sell it for less than $100.
37 Extrinsic Incentive Bias Assuming other people are motivated more by money and external rewards than we ourselves are. You say you work because the job is meaningful but assume your coworkers mainly care about salary.
38 False Consensus Effect Overestimating how many other people share our opinions or behaviors. Because everyone in your social circle supports an idea, you assume most Americans do too.
39 Framing Effect Decisions change depending on how equivalent information is presented. “90% survival rate” sounds more attractive than “10% mortality rate.”
40 Functional Fixedness Seeing objects or ideas only in their conventional roles. You need a paperweight but don’t think to use the heavy coffee mug on your desk.
41 Fundamental Attribution Error Overemphasizing personality and underestimating situational factors when explaining other people’s behavior. A driver cuts you off and you conclude they’re a jerk rather than considering they may be rushing to a hospital.
42 Gambler’s Fallacy Believing past independent random events affect the probability of future ones. A coin lands heads five times, so you think tails is now “due.”
43 Google Effect Remembering information less well when we know it can easily be looked up later. You don’t remember a phone number because you know it is stored on your phone.
44 Halo Effect A positive impression in one area influences judgments in unrelated areas. Because someone is attractive and articulate, you assume they’re also intelligent and trustworthy.
45 Hard-Easy Effect People tend to be overconfident on difficult tasks and underconfident on easy ones. You estimate an 80% chance of answering a very difficult trivia question correctly when your true odds are much lower.
46 Heuristics Mental shortcuts that allow quick judgments without analyzing every detail. You choose a crowded restaurant because you assume crowds indicate good food.
47 Hindsight Bias After an event occurs, believing it was more predictable than it really was. After a stock crashes, people say, “It was obvious that company was going to fail.”
48 Hot Hand Fallacy Believing a recent streak of success necessarily makes continued success more likely. A basketball player makes four shots, so you assume the fifth shot is unusually likely to go in.
49 Hyperbolic Discounting Disproportionately preferring immediate rewards over larger delayed rewards, especially when the immediate reward is available now. You choose $50 today over $100 next year, but prefer $100 in six years over $50 in five years.
50 IKEA Effect Valuing something more because you helped create it. You think the desk you assembled yourself is worth more than an identical preassembled desk.
51 Identifiable Victim Effect Feeling stronger compassion for a specific identifiable person than for a large anonymous group. People donate more to help one named sick child than to statistics describing thousands of sick children.
52 Illusion of Control Overestimating our ability to influence outcomes governed partly or entirely by chance. A gambler throws dice gently when wanting a low number.
53 Illusion of Transparency Overestimating how clearly our internal thoughts and emotions are visible to others. During a presentation you think everyone can see how nervous you are, even though they cannot.
54 Illusion of Validity Remaining overly confident in a judgment even when the evidence supporting it is weak. An interviewer believes they can accurately predict job performance from a 20-minute interview.
55 Illusory Correlation Perceiving a relationship between variables that is weak or nonexistent. You notice two full moons coinciding with strange behavior and conclude full moons cause it.
56 Illusory Truth Effect Repeated statements become more believable merely because they are familiar. After seeing the same false claim online twenty times, it begins to feel true.
57 Impact Bias Overestimating the intensity or duration of our emotional reaction to future events. You imagine losing a promotion would make you miserable for years, but you recover within weeks.
58 In-group Bias Favoring people who belong to our own group. A manager unconsciously gives employees from their alma mater preferential treatment.
59 Incentivization Behavior changes when rewards or penalties are attached to it. Employees make more sales after receiving a bonus for exceeding a target.
60 Just-world Hypothesis Believing people generally get what they deserve and deserve what they get. Someone assumes a poor person must have made bad choices because “hard work always pays off.”
61 Lag Effect Learning improves when repetitions are separated by intervals rather than occurring too close together. Reviewing vocabulary today, three days later, and next week produces better retention than repeating it ten times today.
62 Law of the Instrument Overusing a familiar tool or method regardless of whether it fits the problem. “When all you have is a hammer, everything looks like a nail.”
63 Less-is-Better Effect A smaller objectively inferior option can sometimes seem better when evaluated independently. A nearly full 24-piece dinnerware set may seem more valuable than an incomplete 31-piece set when viewed separately.
64 Leveling and Sharpening Memory simplifies some details while exaggerating or emphasizing others. When retelling an argument, you forget mundane details but emphasize the insulting remark.
65 Levels of Processing Information processed meaningfully or deeply is remembered better than information processed superficially. Thinking about what a new word means helps you remember it better than simply repeating its spelling.
66 Look-Elsewhere Effect Searching many possibilities increases the chance of finding an apparently significant result purely by chance. Researchers test 100 variables and highlight the one that happens to produce p < 0.05.
67 Loss Aversion Losses generally feel more painful than equivalent gains feel pleasurable. Losing $100 hurts more than gaining $100 feels good.
68 Mental Accounting Treating money differently depending on its source or intended purpose even though money is fungible. You spend a $1,000 tax refund freely while refusing to touch $1,000 in savings.
69 Mere Exposure Effect Repeated exposure tends to increase liking or familiarity. A song you initially dislike becomes enjoyable after hearing it repeatedly.
70 Messenger Effect How we respond to information depends partly on who delivers it. You believe identical financial advice more readily when it comes from Warren Buffett than from a stranger.
71 Motivating Uncertainty Effect In some situations, uncertain rewards can motivate more effort than fixed rewards. People work harder for a chance to win either $50 or $100 than for a guaranteed $50 reward.
72 Naive Allocation Dividing resources evenly among available choices without fully considering their merits. Given four investment funds, you automatically put 25% into each.
73 Naive Realism Believing we see reality objectively while people who disagree are biased or uninformed. “Anyone who looks at the facts objectively would agree with me.”
74 Negativity Bias Negative information has a stronger psychological impact than equivalent positive information. One critical comment bothers you more than ten compliments please you.
75 Noble Edge Effect Viewing a company more positively because it appears socially responsible or ethical. You assume a brand’s products are better because the company supports environmental causes.
76 Normalcy Bias Underestimating threats because we assume things will continue functioning normally. Residents ignore evacuation warnings because previous storms caused little damage.
77 Nostalgia Effect Sentimental feelings about the past influence current judgments and behavior. Seeing a childhood candy brand makes you willing to pay more for it.
78 Observer Expectancy Effect Expectations held by researchers or observers can unintentionally influence subjects or interpretation of results. A teacher expecting certain students to succeed subtly gives them more encouragement.
79 Omission Bias Judging harmful actions as worse than equally harmful failures to act. Someone refuses a vaccine because they fear causing a side effect, while discounting the risk of becoming sick by doing nothing.
80 Optimism Bias Believing positive outcomes are more likely for us and negative outcomes less likely. You believe you’re less likely than the average driver to have an accident.
81 Ostrich Effect Avoiding unpleasant or threatening information. An investor stops checking their portfolio during a market crash.
82 Outcome Bias Judging the quality of a decision primarily by its result rather than the reasoning available at the time. A reckless investment makes money, so people conclude it was a good decision.
83 Overjustification Effect External rewards can reduce intrinsic motivation for an activity previously enjoyed for its own sake. A child who loves drawing begins receiving money for drawings and later loses interest when payments stop.
84 Parasocial Trust in AI Human-like interaction with AI can create excessive feelings of trust, intimacy, or authority. Someone tells an AI highly private information because its conversational style feels like talking to a trusted friend.
85 Peak-End Rule We remember experiences largely by their most intense moment and how they ended rather than by the average experience. A vacation with one amazing day and a wonderful final evening is remembered as excellent despite several mediocre days.
86 Pessimism Bias Overestimating the likelihood or severity of negative outcomes. You assume an upcoming interview will go badly despite being well prepared.
87 Planning Fallacy Underestimating how much time, money, or effort future tasks will require. You think a home renovation will take two months even though similar projects usually take six.
88 Pluralistic Ignorance Privately rejecting a norm while incorrectly believing most other people accept it. Everyone in a meeting thinks a proposal is bad, but nobody objects because each person assumes everyone else supports it.
89 Present Bias Giving disproportionate importance to rewards and costs occurring now. You spend money today rather than save for retirement decades away.
90 Primacy Effect Items encountered first are remembered or weighted more strongly. You remember the first few names introduced at a party better than the middle ones.
91 Priming Exposure to one stimulus influences later thoughts or behavior, often without conscious awareness. Reading words related to old age may make concepts associated with aging more mentally accessible afterward.
92 Projection Bias Assuming our current preferences and emotional state will persist into the future. Shopping while hungry, you buy far more food than you’ll actually want later.
93 Reactive Devaluation Discounting an idea because it comes from an opponent or disliked source. Two political parties propose nearly identical policies, but supporters reject the policy when told the opposing party proposed it.
94 Recency Effect Items encountered most recently are remembered better than those in the middle. You remember the final few items on a long grocery list particularly well.
95 Regret Aversion Avoiding decisions because we fear feeling regret if the outcome is bad. You avoid investing altogether because you fear regretting a market decline.
96 Representativeness Heuristic Judging probability based on similarity to a stereotype rather than statistical likelihood. A quiet, bookish person “looks like a librarian,” so you assume they are one despite librarians being relatively rare.
97 Response Bias Systematic tendencies to give inaccurate or distorted answers to surveys or questions. Someone reports exercising five days a week because that sounds socially desirable, even though they exercise twice.
98 Restraint Bias Overestimating our ability to resist temptation. You keep junk food at home because you’re sure you have enough willpower not to eat it.
99 Rosy Retrospection Remembering past experiences more positively than they actually were. You remember college as wonderful while forgetting exams, stress, and financial problems.
100 Salience Bias Giving disproportionate weight to information that stands out. One dramatic Tesla fire affects your perception of EV safety more than millions of uneventful trips.
101 Self-serving Bias Taking personal credit for successes while blaming failures on external circumstances. You credit skill when your stock rises but blame manipulation when it falls.
102 Serial Position Effect Remembering the beginning and end of a sequence better than the middle. From a 20-item list, you remember items 1–3 and 18–20 best.
103 Sexual Overperception Bias The tendency, especially documented among men in some contexts, to overestimate another person’s sexual interest. Friendly conversation is interpreted as flirting when no romantic interest was intended.
104 Social Norms Behavior is strongly influenced by what we believe other people normally do or approve of. Hotel guests reuse towels more often after being told that most other guests reuse theirs.
105 Source Confusion Remembering information while forgetting or misremembering where it came from. You remember a claim but cannot recall whether you read it in a scientific paper or a Facebook post.
106 Spacing Effect Learning spread across multiple sessions produces better long-term retention than massed practice. Studying 30 minutes a day for a week works better than studying 3½ hours the night before an exam.
107 Spotlight Effect Overestimating how much other people notice our appearance and mistakes. You think everyone noticed the small stain on your shirt, but almost nobody did.
108 Status Quo Bias Preferring existing arrangements simply because they are familiar or already in place. You remain with an expensive insurance provider because switching requires effort.
109 Suggestibility Memories and judgments can be altered by suggestions from other people. After someone asks whether the getaway car was red, you later remember it as red even though it was gray.
110 Survivorship Bias Drawing conclusions from successful cases while overlooking failures that disappeared from observation. Studying only successful entrepreneurs makes dropping out of college appear more beneficial than it really is.
111 Take-the-Best Heuristic Choosing between options based on the first highly informative feature that distinguishes them while ignoring other factors. You choose one laptop because its battery life is much better without comparing every other specification.
112 Telescoping Effect Remembering distant events as more recent or recent events as more distant than they actually were. Something that happened five years ago feels like it happened only two years ago.
113 Illusion of Explanatory Depth Believing we understand something in much greater detail than we actually do. You think you understand how a toilet works until someone asks you to explain its mechanism step-by-step.
114 Pygmalion Effect Higher expectations from others can contribute to improved performance. A teacher expects a student to excel, provides more encouragement, and the student’s performance improves.
115 Sunk Cost Fallacy Continuing an activity because of resources already spent, even when stopping would now be better. You keep watching a terrible three-hour movie because you’ve already watched two hours.
116 Zero Risk Bias Preferring to eliminate one small risk completely rather than achieve a larger reduction in overall risk. You prefer eliminating a 2% minor risk entirely rather than reducing a serious 20% risk to 10%.

The count matches the site’s current “116 biases found” listing, from AI Literacy Gap through Zero Risk Bias. thedecisionlab.com

A useful way to study these is not alphabetically, but by families—for example Decision-Making, Memory, Probability & Statistics, Social Psychology, Investing/Economics, Self-Perception, and AI-related biases. That grouping makes the differences between closely related concepts such as Present Bias vs. Hyperbolic Discounting, Primacy vs. Recency vs. Serial Position, and Confirmation Bias vs. Belief Perseverance much easier to understand.

Heuristics