Topic
Laws & principles
UX collects laws the way other fields collect equations - Jakob's, Tesler's, the Gestalt principles - and designers reach for them to settle arguments. The trouble is that a law quoted from memory is easy to misapply; a law you have actually felt is one whose edges you know.
These are the named rules and rules of thumb that turn up in every critique. Each packs a real observation about people into a phrase short enough to wield - which is exactly why it pays to know what the phrase genuinely claims, and where it stops being true.
So each entry hands you the principle to operate rather than recite: you do the thing, watch the effect land on yourself, and come away able to tell when it applies and when someone is just name-dropping it.
The laws & principles entries 15
-
laws & principles
Gestalt: proximity
Things close together are seen as a group; things spaced apart are seen as separate. Proximity is one of the strongest cues for grouping - it usually overrides shape or colour, though a shared boundary or visible connection can override it.
Try the demo -
laws & principles
Jakob's law
People spend most of their time on other sites, so they expect yours to work like those. Familiar patterns are quicker to use because users already know them - you’re reusing the habits the web has taught them.
Try the demo -
laws & principles
Tesler's law
Every process has a minimum complexity that can't be eliminated - only moved. The real question isn't whether to remove it, but who carries it: the user or the team building it. You can see this in action on this page.
Try the demo -
laws & principles
Aesthetic-usability effect
The aesthetic-usability effect is our habit of judging better-looking things as easier to use - whether or not they actually are. Polish buys a benefit of the doubt, smoothing over small frictions and making people more forgiving.
Try the demo -
laws & principles
Pareto principle
The Pareto principle shows that most impact comes from a small part of the cause - about 80% of value from 20% of the things. In products, a few features drive most use.
Try the demo -
laws & principles
Postel's law
Postel's law - the robustness principle - says be conservative in what you send and liberal in what you accept. Take input in whatever shape people naturally give it, then tidy it up yourself, instead of rejecting anything that isn't already perfectly formatted.
Try the demo -
laws & principles
Parkinson's law
Parkinson's law: work expands to fill the time given. Give it a week and it takes a week; give it an afternoon and it’s done by tea - often just as well.
Try the demo -
laws & principles
Occam's razor
Occam's razor: among designs that solve the problem, the simplest one wins. Don't add elements - options, steps, decoration - beyond what the job needs; every extra is one more thing to read, maintain and get wrong.
Try the demo -
laws & principles
Gestalt: similarity
The Gestalt law of similarity tells us we mentally group items that share visual traits - like colour, shape, or size - and perceive them as belonging together, even when spaced apart. Similarity alone suggests they form a set.
Try the demo -
laws & principles
Gestalt: closure
Closure is the mind’s tendency to fill in gaps and complete shapes from incomplete visual cues - perceiving a whole circle, triangle, or icon even when only fragments are shown.
Try the demo -
laws & principles
Gestalt: continuity
Continuity is the eye's natural tendency to follow smooth, unbroken paths. When lines or rows of elements intersect or branch, you group those that continue in the same direction, not those that merely connect.
Try the demo -
laws & principles
Gestalt: common region
Common region is the grouping effect that occurs when items share a boundary: surround some elements with a line or tinted background, and they’ll be perceived as a group - even if other items are closer or equally nearby. It’s one of the strongest grouping cues, alongside visible connections, and typically overrides proximity and similarity.
Try the demo -
laws & principles
Gestalt: prägnanz
Prägnanz - the law of good figure - means the mind naturally prefers the simplest, most stable interpretation of what it sees. When faced with ambiguity, you perceive the cleanest version: a few whole shapes rather than many odd ones. You can see this principle in action on this page.
Try the demo -
laws & principles
Gestalt: uniform connectedness
Uniform connectedness is among the strongest Gestalt grouping cues: elements joined by a line, or enclosed together, are seen as one group - even when they sit far apart or look nothing alike. A visible connection generally beats proximity and similarity, acting at least as strongly as a shared region.
Try the demo -
laws & principles
Gestalt: proximity vs common region
Both group separate items, but in different ways. Proximity groups by closeness - things near each other belong together. Common region groups by shared space - items within one boundary belong together, even if something closer lies outside. When they conflict, the boundary usually takes precedence.
Try the demo
Know these already? Take the laws & principles quiz, or revise the terms with flashcards.