Anchoring Effect
A random wheel-of-fortune spin changes your estimate of how many African nations are in the UN. The spin was meaningless. The effect was real. Why?
19746 min read
Domain
Psychology
Choice, preference, memory, and confidence turning on themselves.
34 entriesFilter these further →
Beginner
Ages 8+, no background needed.
Bystander Effect
If you collapse on a busy street, your chances of getting help may be worse than on a quiet one. Why does a crowd of witnesses make you less safe?
19688 min read
Dunning-Kruger Effect
The less you know, the more confident you feel. The more you know, the more you see how much you don't. Why?
19996 min read
Halo Effect
Why does being attractive make you seem smarter, or sounding confident make you seem right — even when neither is true?
19208 min read
Murphy's Law
If anything can go wrong, will it? The saying is a joke — but the engineering principle behind it is dead serious.
19497 min read
Parkinson's Law
Give yourself a week for a task that takes an hour, and it will take a week. Why does work expand to fill available time?
19556 min read
Placebo Effect
A sugar pill reliably reduces pain in clinical trials — measurably, not just subjectively. How does a fake treatment produce real healing?
19556 min read
Sunk Cost Fallacy
You paid for a concert ticket and now feel terrible. If you hadn't paid, you'd stay home. You paid, so you go. Why does a sunk cost change anything?
19857 min read
The Monty Hall Problem
Three doors, one car. The host opens a losing door and offers you the swap. Does it make any difference whether you take it?
1975 (posed), 1990 (made famous)9 min read
The Peter Principle
Why does every organisation seem to be run by people who are bad at their jobs? Because the good ones got promoted until they weren't.
19696 min read
The Prisoner's Dilemma
Two people can each do better by betraying the other — and end up worse off than if neither of them had.
195018 min read
Baader-Meinhof Phenomenon
You learn a new word. Within a week, you hear it three times. Did the world start using it when you did — or did you just stop filtering it out?
20066 min read
Buridan's Ass
A donkey stands exactly halfway between two identical bales of hay. With no reason on earth to prefer either, does it starve?
c. 1340 (the attribution; the example is far older)14 min read
Cobra Effect
The British paid a bounty for dead cobras to reduce the snake population. When it ended, the population was higher than before. What went wrong?
19008 min read
Cunningham's Law
Ask a question online and wait hours. Post the wrong answer and be corrected in minutes. Why is the urge to correct stronger than the urge to help?
20106 min read
Hanlon's Razor
They didn't do it to hurt you. Probably they just didn't think. How much does it matter?
19806 min read
Hawthorne Effect
Workers became more productive every time the researchers changed conditions — even when they changed them back. What was the actual cause?
1924–1932 (studies), 1958 (effect named)6 min read
Hofstadter's Law
It always takes longer than you think — and that's still true even after you account for the fact that it always takes longer than you think.
19796 min read
Ringelmann Effect
Add more people to a task and each person works harder, right? Experiments show the opposite. Why does individual effort fall as the team grows?
19136 min read
Semmelweis Reflex
A doctor proved handwashing saved lives. He had the data. The medical profession ignored him for twenty years. Why does evidence trigger resistance?
18476 min read
Streisand Effect
The most reliable way to ensure millions of people see something is to try to prevent anyone from seeing it.
2003 (incident), 2005 (term coined)6 min read
The Abilene Paradox
Everyone at the table agreed to a trip that not one of them wanted to take. How does a group choose what every member is against?
197417 min read
Intermediate
Curious teenagers and general adult readers.
Pygmalion Effect
Can a teacher's expectation — with no basis in fact — make a student smarter? The data say yes. The mechanism is more unsettling than the result.
19687 min read
The Paradox of Choice
Put out twenty-four kinds of jam instead of six and fewer people buy any jam at all. More options, fewer decisions.
2004 (the book); 2000 (the jam study)19 min read
Brooks's Law
A software project is six months late. You add more developers. Now it's eight months late. Why?
19756 min read
Conway's Law
Your software will look like your org chart. Not because you planned it, but because you couldn't plan it otherwise.
19685 min read
Dunbar's Number
You can maintain real relationships with about 150 people. Beyond that, a group becomes something different. Is this a law of human nature?
19927 min read
Flynn Effect
IQ scores rise 3 points per decade worldwide. If the tests measure intelligence, are we smarter? Or is something wrong with the tests?
19847 min read
Matthew Effect
Two equally talented people start. One gets a small early advantage. Decades later, the gap is enormous. Where did the extra distance come from?
19688 min read
The Boy or Girl Paradox
A family has two children and one of them is a boy. What are the odds the other is a girl? It depends on how you found out.
1959 (posed), 1961 (retracted in part)13 min read
The Ellsberg Paradox
You know exactly how many red balls there are, and nothing about how many are black. Does knowing more make a bet more attractive?
19617 min read
Berkson's Paradox
Two things with nothing whatever to do with each other can look strongly related — purely because of who ended up in the study.
194615 min read
The Easterlin Paradox
Richer people are happier than poorer people. Yet a whole country getting richer does not seem to get happier.
197423 min read
Advanced
Undergraduate level in the relevant field.
The Allais Paradox
Offered the same improvement in odds twice, most people take it once and refuse it the second time. Both choices feel obviously right.
1952 (posed at the Paris colloquium), 1953 (published)22 min read