Over the past year, I’ve built a collection of 40 psychology laws and cognitive biases — each one explained with real examples, the science behind it, and a quiz to test your understanding.
These aren’t abstract academic concepts. Each one explains something that happens in everyday life: why you hold onto losing investments, why you trust authority figures even when they’re wrong, why you feel like everyone noticed your mistake when they didn’t.
Bookmark this page. It’s the index to all 40.
🧠 Test Yourself First
Before you read, try the 40-Level Psychology Quiz — see how many of these you already know intuitively. Most people get about 60% right. The ones you get wrong are the ones actively influencing your decisions right now.
The Complete List
| # | Law / Effect | Core Idea |
|---|---|---|
| 1 | The Dunning-Kruger Effect | Why beginners are overconfident and experts feel uncertain |
| 2 | The Halo Effect | Why one good trait makes us assume everything else is good too |
| 3 | The Bystander Effect | Why people are less likely to help when others are present |
| 4 | Murphy’s Law | If anything can go wrong, it will — and why that’s useful to know |
| 5 | Confirmation Bias | Why we only see evidence that supports what we already believe |
| 6 | Survivorship Bias | Why we only learn from winners and ignore the failures |
| 7 | The Sunk Cost Fallacy | Why we keep investing in losing bets because we already paid |
| 8 | The Gambler’s Fallacy | Why past random events feel like they should influence the future |
| 9 | The Peak-End Rule | Why we judge experiences by their peak moment and their ending |
| 10 | The Blind Following Effect | Why we follow crowds even when we know better |
| 11 | The Gadfly Effect | How persistent questioning forces better thinking |
| 12 | Tunnel Vision Effect | Why intense focus makes us miss the bigger picture |
| 13 | The Door-in-the-Face Technique | Why making a huge request first makes smaller requests succeed |
| 14 | Segal’s Law | Why having two sources of information is worse than one |
| 15 | The Weakest Link | Why a system is only as strong as its most vulnerable part |
| 16 | Authority Bias | Why we trust experts even when they’re wrong |
| 17 | The Anchoring Effect | Why the first number we hear shapes every decision that follows |
| 18 | The Kuleshov Effect | Why context changes the meaning of everything we see |
| 19 | The Catfish Effect | Why adding a threat to a comfortable environment drives performance |
| 20 | The Birdcage Effect | Why one possession leads to a chain of unnecessary purchases |
| 21 | Analysis Paralysis | Why too many options leads to making no decision at all |
| 22 | The Domino Effect | How one small action sets off a chain reaction of consequences |
| 23 | The Recency Effect | Why we remember the last thing we experienced most clearly |
| 24 | The Primacy Effect | Why the first impression is almost impossible to overwrite |
| 25 | The Ratchet Effect | Why progress is easy to gain but almost impossible to roll back |
| 26 | Herd Mentality | Why we follow the crowd even against our own judgment |
| 27 | The 10,000-Hour Rule | What Malcolm Gladwell got right — and wrong — about mastery |
| 28 | Parkinson’s Law | Why work expands to fill the time available for it |
| 29 | The Hawthorne Effect | Why people perform better simply because they know they’re being watched |
| 30 | The Barnum Effect | Why vague personality descriptions feel uniquely accurate to everyone |
| 31 | The Pygmalion Effect | Why high expectations can literally change someone’s performance |
| 32 | The Matthew Effect | Why the rich get richer and the head start compounds forever |
| 33 | The Butterfly Effect | Why tiny actions in complex systems produce enormous consequences |
| 34 | Goodhart’s Law | Why when a measure becomes a target, it stops being a good measure |
| 35 | The Pareto Principle (80/20 Rule) | Why 80% of your results come from 20% of your efforts |
| 36 | The Streisand Effect | Why trying to suppress information only amplifies it |
| 37 | The IKEA Effect | Why we value things more when we built them ourselves |
| 38 | The Cobra Effect | Why well-intentioned solutions sometimes make problems worse |
| 39 | The Spotlight Effect | Why we think everyone notices our mistakes — but they don’t |
How to Use This Collection
You don’t need to read all 40 in one sitting. A better approach: pick one that sounds familiar, read the full explanation, then spend a week noticing where it shows up in your own life.
The effects that surprised me most when I first learned them: Survivorship Bias (it explains why most business advice is useless), the Sunk Cost Fallacy (I kept a losing investment for two extra years because of this), and the Dunning-Kruger Effect (I see it in myself constantly).
Each page includes the original research, a real-world example, and a short quiz. The quiz questions are harder than they look — they test application, not memorization.
📬 One Law Per Week
I’m working through all 40 in my own life. If you want to follow along, the best articles are published at ordinarymantrying.com — no newsletter, just the blog.
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