Adaptation
The tendency to get used to a change in your life, also called the hedonic treadmill: over time a good change stops lifting you and a bad one stops hurting as much.
Hedonic adaptation is the tendency to get used to changes, good and bad, so their effect on how you feel shrinks over time. A raise, a car, a new place: the lift fades as it becomes normal. Evidence: decent In a three-month study of 481 students, a good change wore off two ways: the good feelings it brought faded, and people started wanting more. It wore off more slowly when they kept appreciating the change and it kept bringing variety. Evidence: decent A survey over time, not an experiment. Evidence: decent
The classic study, from 1978, compared 22 big lottery winners with 22 people who hadn't won. The winners weren't happier, and they got less pleasure from everyday things. Evidence: decent Small numbers, and one moment in time. Evidence: decent
Where it gets oversold: "you bounce back from anything". Large surveys that followed people for years found that divorce, a partner's death, losing a job and disability can leave lasting drops, and people differ a lot in how far they adapt. Evidence: decent Everyone has a usual level of happiness, but it isn't fixed, and it can move. Evidence: decent
Why it matters
People adapted more slowly to experiences than to things they bought, which fits booking the experience, and also means a bad trip can keep stinging. Evidence: decent Variety went with slower adaptation, which is the point of rotating your lift. Evidence: decent Keeping on appreciating a change, close kin of savouring, was the other brake in that study. Evidence: decent