UX Laws Reference
Practical design principles drawn from perception, cognition, behavior, and human-computer interaction.
Updated 2026-08-12
Interaction and Effort
| Principle | Design meaning |
|---|---|
| Doherty Threshold | Fast, continuous feedback helps people maintain attention and feel in control of an interaction. |
| Fitts's Law | Large targets positioned near the pointer or thumb are generally faster and easier to acquire. |
| Hick's Law | More numerous or complicated choices generally increase decision time; structure choices instead of merely hiding them. |
| Tesler's Law | Every system retains some irreducible complexity; place that burden where it creates the least user effort and risk. |
| Postel's Law | Accept reasonable variation carefully while producing predictable output, without weakening validation or security. |
Perception and Grouping
| Principle | Design meaning |
|---|---|
| Aesthetic-Usability Effect | People may perceive an attractive interface as easier to use, but visual polish cannot replace usable behavior. |
| Law of Common Region | Elements enclosed by the same boundary are likely to be understood as a related group. |
| Law of Proximity | Items placed close together are usually perceived as more related than items separated by space. |
| Law of Prägnanz | People tend to interpret complex or ambiguous forms using the simplest stable organization available. |
| Law of Similarity | Elements sharing visual characteristics are likely to be interpreted as belonging together. |
| Law of Uniform Connectedness | An explicit visual connection creates a particularly strong signal that elements are related. |
| Von Restorff Effect | An item that differs meaningfully from surrounding items is more likely to attract attention and be remembered. |
Memory and Experience
| Principle | Design meaning |
|---|---|
| Jakob's Law | People bring expectations learned from other products, so familiar conventions usually reduce learning effort. |
| Miller's Law | Working memory is limited; reduce recall demands and organize information into meaningful chunks rather than treating a fixed number as universal. |
| Peak-End Rule | Memories of an experience are influenced strongly by intense moments and by how the experience ends. |
| Serial Position Effect | People often remember early and late items better than those in the middle of a sequence. |
| Zeigarnik Effect | Interrupted or unfinished tasks can remain mentally active; visible progress and resumable state can help users return. |
Goals and Scope
| Principle | Design meaning |
|---|---|
| Goal-Gradient Effect | Motivation often increases as visible progress approaches a meaningful goal. |
| Occam's Razor | When alternatives explain and solve the problem equally well, prefer the one requiring fewer assumptions. |
| Pareto Principle | A minority of causes may account for a large share of outcomes; verify the actual distribution before prioritizing. |
| Parkinson's Law | Work tends to expand to consume available time, making clear limits and milestones useful for controlling scope. |