UI/UX laws
Laws of UX
18 research-backed principles behind ui-element-best-practices. Every rule cites a mechanism, not a preference. Each law below gets a plain-language definition and a live without/with example you can compare directly.
Structure inspired by lawsofux.com, rebuilt with this site’s own design tokens.
Interaction & Speed
Interaction & Speed
How fast and effortless a single action feels.
Fitts's Law
The time it takes to move to and select a target is a function of the target's size and the distance to it: bigger, closer targets are faster and easier to hit.
Hick's Law
Decision time increases with the number and complexity of choices offered: more options mean slower decisions.
Jakob's Law
Users spend most of their time on other products, so they expect yours to work the same way theirs do.
Doherty Threshold
Productivity and engagement rise when a system responds to input in under about 400 milliseconds.
Memory & Attention
Memory & Attention
What people notice, hold onto, and recall later.
Miller's Law
The average person can hold only about 7 (±2) items in working memory at once.
Serial Position Effect
People remember the first and last items in a list best, and the items in the middle worst.
Zeigarnik Effect
People remember unfinished or interrupted tasks better than completed ones. Open loops keep nagging at attention.
Peak-End Rule
People judge an experience mostly by its most intense point (the peak) and how it ends, not by the average of every moment.
Perception & Gestalt
Perception & Gestalt
How people group, simplify, and judge what they see.
Law of Prägnanz
People perceive and interpret ambiguous or complex shapes in the simplest form possible.
Law of Proximity
Objects near each other are perceived as more related than objects farther apart.
Law of Common Region
Elements that share a clearly defined boundary (a border, background, or container) are perceived as belonging to the same group.
Law of Similarity
Elements that look visually similar are perceived as related or performing the same function, even when they aren't near each other.
Law of Uniform Connectedness
Elements visually connected by a line, arrow, or shared connector are perceived as more related than elements that are simply close together or similarly styled.
Von Restorff Effect
When several similar items are present, the one that differs from the rest is the one most likely to be remembered.
Aesthetic-Usability Effect
People perceive more aesthetically pleasing designs as easier to use, whether or not they actually are.
Motivation & Complexity
Motivation & Complexity
What keeps people moving toward a goal, and who pays for complexity.
Goal-Gradient Effect
Motivation to complete a task increases as people get closer to the goal, and effort accelerates near the finish line.
Tesler's Law
Every process has a fixed amount of irreducible complexity. The only question is who deals with it, the system or the user.
Postel's Law
Be liberal in what you accept from users, and conservative in what you send back to them: the robustness principle.
Source
Where this comes from
These laws back the ui-element-best-practices skill, which reviews individual components (buttons, forms, navigation, modals, cards, tables, states, notifications, and tooltips) against them. Pair it with ui-ux-best-practices for full-screen review.