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UX laws,demonstrated on you

Every UX law gets explained the same way: a sentence, a diagram, and your agreement. You nod, you close the tab, you design the same screen you were going to design anyway. So this one doesn't explain. Open a card and the law runs its experiment on you, using your hands and your numbers.

Thirty lawsAll of them built

Things you can time

A stopwatch settles these. Each one measures something your hands or your eyes actually did, and draws its curve from your own numbers.

Fitts's Law Distance and size decide how fast you can hit a thing. You already know this. Your toolbar doesn't. Open Hick's Law Every option you add taxes the person deciding. The page works out whether your own times grew like a curve or a straight line. Open Doherty Threshold Under 400ms you stay with the machine. Thirty rounds at five delays, measuring what waiting does to your own pace. Open Goal-Gradient Effect You push harder when you can see the end. The same fifteen steps twice, once with a progress bar and once with no idea when it stops. Open Parkinson's Law Work expands to fill the time you were told it takes. Six identical rounds, two estimates, and nothing enforcing either. Open Choice Overload Every option you add is paid for by everyone who did not want it. Twelve timed picks across grids of two, six, twelve and twenty-four. Open Cognitive Load The same task twice: once with the price on the row, once with the price in a key you have to hold. Identical work, one of them harder. Open

Things you keep

What survives after the screen is gone — how much you held, which parts came back, and what an experience is reduced to once it is over.

Serial Position Effect You keep the start and the end. Four lists of eight words, and the page draws the curve out of your own recall. Open Miller's Law Seven, plus or minus two — the most misquoted number in design. Two rounds of the same digits, and only the spacing changes. Open Working Memory Five letters, then three seconds of arithmetic, or twelve. Not how much you can hold — how fast it goes when something else gets in. Open Chunking Twelve characters, four seconds, typed back. Three runs unbroken and three in groups of four, and the only difference is two gaps. Open Peak-End Rule You remember the worst moment and the last one, and barely count the length. Two waits, then one honest question. Open Zeigarnik Effect Unfinished things stay with you. Ten small jobs, five of them taken away part-way, and a memory test at the end. Open

Things your eye groups for you

Five cues fighting over the same field. You have already grouped what is below before you decide anything, and the cues do not carry equal weight.

Law of Proximity Near means related — until a box, a line or a colour disagrees. Eight arrangements, and the page works out which force your eyes follow. Open Law of Similarity Things that look alike are read as one thing, even when they are nowhere near each other. Set that against proximity and see which wins. Open Law of Common Region A drawn boundary beats being close. Two tiles at opposite ends of a border group harder than two tiles touching. Open Law of Uniform Connectedness One thin grey line, and the two things it joins become one thing. It beats closeness, colour and a drawn box, and it is the cheapest cue you have. Open Law of Prägnanz A triangle that is not there, made of three circles with a bite out of each. Pull the figure apart yourself and it still comes back. Open

Things that arrive before you look

All of these happen ahead of any conscious decision. You know where the control is before you find it, you have judged the thing before using it, and you brought a model of it with you.

Jakob's Law You already know where the close button is on a product you have never opened. Twelve screens with the icons stripped off, and one question each. Open Aesthetic-Usability Effect Two panels that are the same panel in different clothes. You answer which was easier before the page shows you what your hands actually did. Open Von Restorff Effect The odd one out is the one you keep. Five lists of nine, one word boxed, and never at the ends where position could take the credit. Open Selective Attention You look where the job is and filter out the rest. Two identical labels per screen, one where banners live, then a memory test. Open Mental Model Six ordinary controls. Say what each one will do before you touch it, then touch it. Your prediction is the reading. Open Cognitive Bias A number you were shown for no reason, and the estimate you made afterwards. Six questions, a coin-flipped anchor, and one of you. Open

Things that shape the work

Not about you. These are claims about how systems and effort behave, so nothing here takes a reading — you move the parts and watch what refuses to change.

Postel's Law Be liberal in what you accept. Eight ways people really write a phone number, and a strict field that takes exactly one. Open Tesler's Law Complexity does not go away. It gets moved. Push nine decisions between the app and yourself and watch the bar refuse to shorten. Open Occam's Razor Twelve parts on a departure board and three questions it has to answer. Take parts off until it stops answering them. Open Pareto Principle Twenty units of effort across twelve features, spent before anyone uses it. Then the traffic arrives and decides which two mattered. Open Flow Challenge above your skill is anxiety, below it is boredom, and the band between them is thin. Slide the difficulty and watch it leave. Open Paradox of the Active User The instructions are one click away and you will not read them. You are slower for it, and you are not wrong to do it. Open

Where the list comes from. The collection I'm working through is Laws of UX by Jon Yablonski — the canonical version, and worth reading in full. His content is licensed CC BY-NC-ND 4.0, which permits sharing but not rewriting, so none of the wording here is his. The laws themselves belong to the psychologists who found them.

Who wrote it. Claude did. The prose, the demonstrations and the statistics, all of it, working from my direction and my edits. I picked the laws, decided what each page had to prove, and threw out the versions that did not. I would rather say that than let you assume otherwise.