Wendy Wood followed students as they transferred to a new university. Their habits, like exercising or watching TV, only survived if the new setting resembled the old one. Habits are glued to the places and cues that trigger them. Other studies find people who've just moved respond more strongly to nudges to change their behavior.
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.