40 Psychological Effects:

1. Bepp's Law: After a strong initial stimulus, the emotional response to a similar stimulus the second time is much smaller. Free delivery for a 20-dollar takeout becomes unacceptable at 5 dollars, and reactions to 6 dollars are much less.
2. Barnum Effect: People tend to believe vague personality predictions tailored to themselves. You appear calm on the surface but wild inside; with strangers, you have no topics, but with close friends, you chat freely.
3. Sandwich Effect: Criticism is more easily accepted when sandwiched between praise. "The soup is really good" (praise) but "it's a bit salty" (criticism); next time, I can drink three bowls if it's lighter (praise).
4. Birdcage Effect: Accidentally receiving unnecessary items leads to unconsciously adding more unnecessary things. Giving a leader a name-brand tie, he might wear a matching shirt and suit to work a few days later.
5. Broken Window Effect: If a window is broken and left unrepaired, other windows may mysteriously get broken too. The environment sends strong implicit and suggestive signals.
6. IKEA Effect: Customers who put effort into assembling furniture tend to irrationally love it, overestimating its value and not wanting others to own what they worked on.
7. Completeness Effect: An unfinished circle will be mentally remembered as needing to be completed. Apple fans buy all three pieces of the Apple set for perfection; collecting all five blessings on Alipay feels complete.
8. Puppy Effect / Trial Effect: When children bring a puppy home and bond with it over a few days, they are very likely to buy it.
9. Validity Effect: After betting on a horse, bettors become more confident in their choice; after stock trading, they become stock market experts.
10. Dunning-Kruger Effect: Less capable people overestimate themselves; the worse they are, the more confident, and the stronger they are, the more humble.
11. Primacy Effect: The first impression in a meeting dominates the other person's perception. Girls dressed beautifully, boys looking handsome—first impressions are crucial.
12. Ultimatum Effect: Setting a deadline causes people to subconsciously rush to finish before it. One way to cure procrastination.
13. Zeigarnik Effect: Unfinished tasks that are interrupted leave a deeper impression than completed ones. The next episode always leaves viewers eager for more.
14. Murphy's Law: If you worry that something will happen, it’s more likely to happen. Things that are prone to errors always go wrong.
15. Exposure Effect: The more familiar you are with something, the more you like it. Increased communication raises familiarity and attraction.
16. Pygmalion Effect: People with expectations of failure tend to fail; those with expectations of success tend to succeed. Self-fulfilling prophecy.
17. Lucifer Effect: Under powerful situational forces, good people can do bad things. The angel Lucifer falls and becomes Satan.
18. Placebo Effect: Belief is powerful; regardless of whether a drug works, it can provide psychological comfort, and the body's self-healing ability can improve health.
19. Door-in-the-Face Effect: Start with a small request; after it’s accepted, make a bigger request. Don’t start with high demands.
20. Face-Saving Effect: After a large request is refused, make a smaller one; the smaller request is more likely to be accepted. Advocating for tearing down a roof, people are willing to open windows.
21. Romeo and Juliet Effect: External obstacles are seen as tests of love, creating rebellious psychology; the more parents oppose, the more determined the couple is to stay together.
22. In-Group Effect: Viewing others as part of oneself makes their words more trustworthy and acceptable.
23. Bridan Donkey Effect: When faced with two equally tempting options, people hesitate and end up missing both. Easy job far from home vs. high salary with overtime—hesitation leads to missed opportunities.
24. Zealot Effect: Outsiders who join a community become more fervent and devout than native members, strongly believing in the doctrine.
25. Halo Effect: Liking someone makes you like everything about them. Forming good or bad impressions of one trait influences attitudes toward other traits.
26. Ogle's Law: Hiring someone stronger than yourself can make your company a giant. Emphasizes the importance of talent.
27. Beauty Effect: Attractive people are often mistakenly assumed to be good in other areas too. Judging by appearance.
28. Bock's Theorem: The best ideas and decisions often emerge during debates. Without friction, there’s no refinement; disagreements lead to better insights.
29. Lober's Law: A manager’s most important concern is not what happens when they are present, but what happens when they are absent.
30. Hedgehog Theory: When cold, people huddle together for warmth but need to keep a distance to avoid hurting each other. Even close relationships require boundaries.
31. Choice Blindness: People often forget their own choices, such as whether they locked the door.
32. Echo Chamber Effect: People tend to associate with those who share similar opinions. Birds of a feather flock together.
33. Forbidden Fruit Rebellion: The more you are forbidden to do something, the more you want to try. Adam and Eve’s curiosity led them to eat the forbidden fruit and be expelled from Eden.
34. Rosenthal Effect: Students randomly labeled as geniuses show significant improvement after being told so, performing remarkably.
35. Mushroom Law: When entering society, new workers are often ignored and treated like mushrooms—kept in the dark and fed manure. As they grow closer to reality, unrealistic fantasies fade.
36. Flywheel Effect: A stationary flywheel requires a lot of effort to start turning, but once it reaches a critical point, it spins easily without much effort. Persistence pays off; once past the threshold, progress accelerates.
37. Bucket Law: The amount of water a bucket can hold depends on its shortest plank. Development depends on fixing weaknesses; always seek to improve.
38. Wild Horse Ending: Blood bats suck very little blood from wild horses, not enough to kill, but the horses die from furious running. Don’t get angry over trivial matters or hurt yourself with others’ faults.
39. Alcohol and Sewage Law: A spoon of alcohol poured into sewage results in sewage; a spoon of sewage poured into alcohol remains sewage. Good kids in chaotic departments may become chaotic themselves.
40. Matthew Effect: The rich get richer, and the poor get poorer. Those who have will be given more; those who have nothing will have even that taken away.