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
Kind
Effect
Documented causal patterns where something in the world behaves differently from how most people expect.
15 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
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
The Butterfly Effect
Can a butterfly in Brazil cause a tornado in Texas? Not by force — but by changing everything that follows.
1963 (discovery), 1972 (butterfly metaphor coined)7 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
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
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
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
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
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