In the 1880s, Hermann Ebbinghaus memorized thousands of nonsense syllables and tracked how many stuck. Forgetting was steep at first: roughly half gone within an hour, two-thirds within a day, then the curve flattened out. A modern replication in 2015 found almost exactly the same curve. The good news: every review slows it down.
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.