Norton, Mochon and Ariely had volunteers assemble flat-pack storage boxes. They were willing to pay noticeably more for their own box than for an identical pre-built one, and valued their clumsy origami almost as highly as experts' work. Dubbed the “IKEA effect,” it vanishes if the item is taken apart or left unfinished: it's the completed effort that breeds attachment.
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.