Which bias is this?
Which bias is this? A daily quiz on the cognitive biases that quietly shape your decisions: read a real-world scenario, name the bias behind it, and learn why your mind does it. A new scenario waits every day.
“Choosing news sources that echo your existing politics and dismissing the rest as biased.”
Pick the bias behind the scenario. A new one waits each day — come back to keep your streak.
Spot the bias — every scenario
60 everyday scenarios and the cognitive bias behind each — read the full explanation on any bias page.
“Choosing news sources that echo your existing politics and dismissing the rest as biased.”
→ Confirmation bias“Sitting through a bad film to the end because you paid for the ticket.”
→ Sunk-cost fallacy“Feeling “basically an expert” after a single tutorial or one popular-science book.”
→ Dunning–Kruger effect“A high “original price” making a sale price feel like a bargain.”
→ Anchoring bias“Studying only successful founders for “the habits of success,” ignoring identical habits in those who failed.”
→ Survivorship bias“Fearing plane crashes more than car crashes, though driving is far deadlier per mile.”
→ Availability heuristic““The market crash was obviously coming” — said only after it happened.”
→ Hindsight bias“Assuming attractive people are also kinder, smarter, or more competent.”
→ Halo effect“Holding a losing investment to avoid “realizing” the loss.”
→ Loss aversion““90% fat-free” outselling the identical “10% fat”.”
→ Framing effect“One harsh comment outweighing ten compliments.”
→ Negativity bias“Expecting a rising market to keep rising because it rose lately.”
→ Recency bias“Assuming a driver who cut you off is rude, not rushing to an emergency.”
→ Fundamental attribution error““I aced it” after a pass, but “the test was unfair” after a fail.”
→ Self-serving bias“A stock or trend surging simply because more people are piling in.”
→ Bandwagon effect“Assuming your project will finish on time though most similar ones overran — the planning fallacy.”
→ Optimism bias“Home renovations and software projects routinely running double their estimate.”
→ The planning fallacy“Betting on black after five reds on roulette — the odds are still about 50/50.”
→ The gambler’s fallacy“Staying on a worse phone, insurance, or energy plan because switching is effort.”
→ Status-quo bias“Patients following an obviously wrong instruction because "the doctor said so."”
→ Authority bias“Fearing a rare-disease diagnosis from a positive test, ignoring that the disease’s rarity makes most positives false.”
→ Base-rate neglect“The jam study: a 24-flavour display drew more browsers but about ten times fewer buyers than a 6-flavour one.”
→ Choice overload“A painful medical procedure remembered as less bad when its final moments were milder — even if it lasted longer overall.”
→ The peak-end rule“The "tappers and listeners" study: tappers of a tune were sure listeners would recognise it about half the time; the real rate was ~2.5%.”
→ The curse of knowledge“Being sure everyone noticed the stain on your shirt or your one clumsy comment in a meeting.”
→ The spotlight effect“The Economist’s pricing: a print-only option priced the same as print+web made print+web the "obvious" deal.”
→ The decoy effect“A song you disliked growing on you after repeated play.”
→ The mere-exposure effect“Valuing self-built furniture, gardens, or code above objectively better alternatives.”
→ The IKEA effect“Judging the same action as fine from your side and outrageous from the other.”
→ In-group bias“Most drivers rating themselves safer than average.”
→ Illusory superiority“Not checking your investment account when markets fall.”
→ The ostrich effect“A cliffhanger keeping a show on your mind until the next episode.”
→ The Zeigarnik effect“In the classic mug experiment, people given a mug demanded roughly twice the price to sell it that others would pay to buy the same mug.”
→ Endowment effect“A smoker who knows smoking is harmful decides "the research is overblown" rather than quit.”
→ Cognitive dissonance“Throwing dice harder for high numbers and softer for low ones, as if force affects the roll.”
→ Illusion of control“Choosing $50 now over $100 in a year, but $100 in six years over $50 in five — the same gap, opposite choice.”
→ Hyperbolic discounting“Showing someone facts that debunk a political myth they believe, after which they cling to it harder.”
→ Backfire effect“Assuming a robbery or assault victim "should have known better" or was somehow asking for it.”
→ Just-world hypothesis“Confidently identifying confirmation bias in someone you disagree with, certain you have none yourself.”
→ Bias blind spot“Learning a new word, then "suddenly" seeing it in three articles that week.”
→ Frequency illusion“Told someone is quiet and loves books, guessing "librarian" over "salesperson" — though salespeople vastly outnumber librarians.”
→ Representativeness heuristic“Studies where people’s "90% confidence intervals" contain the true answer only about half the time.”
→ Overconfidence effect“Assuming "most people" vote the way you do because everyone in your circle does.”
→ False-consensus effect“Betting more on a gambler or basketball player who is "hot" after several wins or makes.”
→ Hot-hand fallacy“A horoscope saying "you have a great need for others to like you, yet tend to be self-critical" feeling spot-on.”
→ Barnum effect“You were late because of traffic; your colleague was late because they’re disorganised.”
→ Actor–observer bias“Judging a technology you like (or a brand you love) as both more beneficial and less risky than the evidence shows.”
→ Affect heuristic“Believing it always rains right after you wash the car, recalling the hits and forgetting the dry days.”
→ Illusory correlation“Remembering the first few items on a long grocery list and forgetting the middle.”
→ Primacy effect“Seeing "hot spots" on a map of random events and inferring a cause.”
→ Clustering illusion“Assuming a presentation will go badly despite a strong track record.”
→ Pessimism bias“Wanting a banned book or film far more precisely because it was banned.”
→ Reactance“Refusing a vaccine with a tiny risk while accepting a larger risk from the disease, because action feels riskier.”
→ Omission bias“A goalkeeper diving left or right on a penalty, though staying centred saves more — because diving "looks" like trying.”
→ Action bias“A $1,000 watch seeming cheap after you were shown a $10,000 one first.”
→ Contrast effect“Feeling sure everyone can tell you’re anxious during a speech, when the audience notices little.”
→ Illusion of transparency“A minor risk becoming a public panic as media coverage feeds on itself.”
→ Availability cascade“Students whose teachers were told (at random) they were "high potential" improving more over the year.”
→ Pygmalion effect“Grocery shopping hungry and buying far more than you’ll want to eat.”
→ Projection bias“Confidently planning to resist temptation when full, then caving when hungry or tired.”
→ Empathy gap