Your users are predictable.
Learn why. Design better.
A growing collection of psychology principles, cognitive biases, and behavioral patterns — each broken down with interactive demos and practical tips.
AI builds screens in seconds.
But it can't tell you why users bounce.
Do this. Not that.
Every article ends with concrete do's and don'ts. Copy them into your next Figma file. We won't tell.
Zero jargon. All signal.
We read the academic papers so you don't have to. Each principle in plain language, ~5 min read.
Free. Forever. Seriously.
No paywall. No "sign up to continue." Open knowledge for anyone who builds digital products.
Scroll it. Tap it.
Break it. Fix it.
Every principle comes with live comparisons inside real phone and browser frames.
AI is your copilot,
not your pilot.
It generates layouts in seconds. But it can't tell you why users bounce. That part's on you — and that's what makes you valuable.
New Lessons every week
228 principles from decades of behavioral research
Built for the AI era.
AI generates the layout. You still need to know why it works — or why it doesn't. This is the missing layer.
The essentials
Hick's Law
More options = harder decisions
Fitts's Law
Bigger + closer = faster to tap
Cognitive Load
Every piece of information on a screen asks something of the people looking at it
Miller's Law
People can hold about 7 (plus or minus 2) items in working memory
Jakob's Law
Users expect your site to work like the ones they already know
Peak-End Rule
People judge experiences by their peak and their ending
Von Restorff Effect
The thing that stands out is the thing that gets remembered
Tesler's Law
Complexity can only be moved, never destroyed
Stop guessing,
start designing.
228+ psychology principles with interactive demos you can actually play with. Free and open — forever.
Get started