Suppose 1% of women screened have breast cancer, the mammogram catches 9 in 10 cases, and it wrongly flags 9% of healthy women. If a test comes back positive, what's the actual chance of cancer? About 1 in 10. Yet among 160 gynecologists questioned by Gerd Gigerenzer, the most common answer was 90%. Out of 1,000 women, that's 9 true alarms versus 89 false ones: put that way, the math becomes obvious.
Remembering is not replaying a recording — it is rebuilding. Each time you recall a memory, it becomes temporarily malleable and can be altered before being stored again. That is why two people can sincerely remember the same event… differently.
In 2003, Johnson and Goldstein compared European countries. Where you must tick a box to become a donor, consent rates ranged from 4% to 28%. Where you're a donor by default unless you opt out, they topped 85%. People aren't more generous on one side; most simply stick with whatever option was chosen for them.