Columbia researchers handed out coffee loyalty cards: one needed 10 stamps, the other 12 but came with 2 already stamped. Either way, 10 purchases remained. Yet customers completed the “head start” card faster. And the closer they got to the reward, the faster they bought: it's called the goal-gradient effect.
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.