In 1973, researchers picked out preschoolers who loved drawing. Some were promised a certificate for drawing. Days later, left free to play, those children drew about half as much as the others. Kids who got the same reward as a surprise kept their enthusiasm. An expected reward turns play into work, as a review of 128 experiments confirmed.
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.