Clarity
One law. One job.
Each entry explains the psychology, the takeaway, and how to apply it — without burying the point in academic language.
UX Principles
Design for how people think.
Psychology for better interface design. Explore 30 evidence-based UX laws with practical guidance and curated reading.
30 laws
Evidence-based rules for how people see, decide, remember, and act in interfaces.
Seven principles
Foundational pillars that connect individual laws into a coherent design practice.
Weekly reading
Curated research links, verified and refreshed every Monday. No account required.
Built to scan
Short takeaways, design applications, and shareable cards for every law.
Design
Looks simple. Works deeper.
A compact reference for interface psychology — large enough for real product decisions, small enough to keep open while you design.
Practice
Research, then craft.
Origins, FAQs, and weekly reading sit behind the headline so you can go as deep as the decision needs.
Laws
Psychology. Fast and practical.
30 principles for building interfaces that feel obvious on first use.
Visual Hierarchy & Perception
Aesthetic-Usability Effect
Users often perceive aesthetically pleasing design as more usable.
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Cognitive Load & Decision Making
Choice Overload
People become overwhelmed when presented with too many options.
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Cognitive Load & Decision Making
Chunking
Break information into meaningful groups to aid comprehension.
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Attention & Focus
Cognitive Bias
Systematic thinking errors shape how users perceive and decide.
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Cognitive Load & Decision Making
Cognitive Load
Mental effort required to use an interface should be minimized.
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Interaction & Behavior
Doherty Threshold
Productivity peaks when system response stays under ~400ms.
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Interaction & Behavior
Fitts's Law
Time to reach a target depends on its size and distance.
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Interaction & Behavior
Flow
Immersive focus emerges when challenge matches skill without interruption.
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Interaction & Behavior
Goal-Gradient Effect
Motivation increases as users get closer to completing a goal.
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Cognitive Load & Decision Making
Hick's Law
Decision time grows with the number and complexity of choices.
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System Design Principles
Jakob's Law
Users expect your site to work like others they already know.
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Visual Hierarchy & Perception
Law of Common Region
Elements within a bounded area are perceived as a group.
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Visual Hierarchy & Perception
Law of Proximity
Near elements are perceived as related.
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Visual Hierarchy & Perception
Law of Prägnanz
People interpret ambiguous visuals in the simplest form possible.
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Visual Hierarchy & Perception
Law of Similarity
Similar elements are perceived as belonging together.
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Visual Hierarchy & Perception
Law of Uniform Connectedness
Visually connected elements feel more related than disconnected ones.
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Attention & Focus
Mental Model
Users bring expectations from prior experience to your product.
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Cognitive Load & Decision Making
Miller's Law
Working memory holds roughly 7±2 items at once.
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System Design Principles
Occam's Razor
Prefer the simplest solution that works.
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Attention & Focus
Paradox of the Active User
Users skip manuals and learn by doing immediately.
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System Design Principles
Pareto Principle
Roughly 80% of outcomes come from 20% of causes.
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Attention & Focus
Parkinson's Law
Work expands to fill available time.
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Memory & Recall
Peak-End Rule
Experiences are judged by their peak moments and the ending.
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System Design Principles
Postel's Law
Be liberal in what you accept; conservative in what you send.
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Attention & Focus
Selective Attention
Users focus on stimuli relevant to their current goal.
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Memory & Recall
Serial Position Effect
First and last items in a series are remembered best.
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System Design Principles
Tesler's Law
Every system has irreducible complexity — shift it from user to system.
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Visual Hierarchy & Perception
Von Restorff Effect
Distinct items among similar ones are remembered best.
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Memory & Recall
Working Memory
Temporary storage for information needed to complete a task.
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Memory & Recall
Zeigarnik Effect
Incomplete tasks stay in memory better than completed ones.
Learn more ›Principles
Seven pillars. One practice.
Beyond individual laws, these foundations shape how teams build products that stay usable as they grow.
User-Centered Design
Prioritize user needs, goals, and context throughout the design process.
Learn more ›Usability
Make products easy to learn, efficient to use, and forgiving of mistakes.
Learn more ›Consistency
Maintain predictable patterns so users can transfer learning across the product.
Learn more ›Accessibility
Design products that work for people with diverse abilities, devices, and contexts.
Learn more ›Human–AI
39 principles for designing with models.
39 topics across 9 categories — from probabilistic foundations to sustained reliance.
Probabilistic Foundation
Treat the model as a probabilistic service. Design for inference, generation, and the spread of possible outputs — not a single fixed function.
View topics ›Expectation Setting
Users form a mental model before they read the first result. Clarify capability, limits, and AI involvement early.
View topics ›Calibrated Trust
Match reliance to reliability. Reduce overtrust in weak output and underuse of useful help.
View topics ›Transparency
A black box cannot be trusted appropriately. Make reasoning and evidence inspectable without drowning the workflow in noise.
View topics ›Control & Agency
Human and system share the wheel. Accept, reject, edit, undo, and override should stay one gesture away.
View topics ›Graceful Failure
Error is the default case, not the edge case. Make uncertainty, recovery, and escalation first-class paths.
View topics ›Co-Creation
Keep the artifact malleable. Treat generated work as a draft the user can shape, not a verdict they must accept.
View topics ›Responsible Autonomy
The more the system acts on its own, the more the interface is a governance surface. Bound action by stakes, reversibility, and permission.
View topics ›Sustained Reliance
Keep the conditions of healthy use intact over time: wait states, cost, quality, drift, ownership, and change.
View topics ›Reading
Latest reading
Curated weekly · Links verified July 25, 2026
Featured
Progress Indicators That Motivate
Visible progress increases completion by showing how close users are to the finish line.
Featured
Simplifying Choice Architecture
Too many options slow users down. Reduce visible choices and highlight a recommended path.
Featured
Designing for Active Users
Most people skip manuals and learn by doing. Interfaces should teach in context, not upfront.
Featured
Familiar Patterns vs. Novel Experiences
When to follow conventions users already know — and when novelty is worth the learning cost.
Featured
Why Peak Moments Shape Memory
People remember experiences by their emotional highs and the ending — not the average of every step.
Featured
Reducing Cognitive Load in Forms
Four practical principles to make forms easier to complete without sacrificing the data you need.
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