Laws of UX

Overview

Core Principles (3 Key Takeaways)

• Design principles must be direct, clear, and actionable
• Effective principles are opinionated with focused prioritization
• Memorable principles are more likely to be implemented

The 10 Laws

1. Jakob’s Law

Core Concept: Users expect consistency across familiar products.

Users apply their knowledge from one product to similar ones. Key strategies include leveraging existing mental models, reducing friction through common design patterns, and aligning product design with user expectations. Begin with established conventions before innovating.

2. Fitts’s Law

Core Concept: Target acquisition time depends on distance and size.

Touch targets should be large, well-spaced, and easily accessible. Pairing text labels with inputs improves usability across devices.

3. Hick’s Law

Core Concept: Decision time increases with choice complexity.

Strategies to reduce cognitive load include minimizing options during critical moments, breaking tasks into steps, highlighting recommendations, and using progressive onboarding. Too many interface options indicates designers don’t fully understand user needs.

4. Miller’s Law

Core Concept: Working memory limits us to approximately 7 (±2) items.

Organize content into chunks using hierarchy, formatting, and appropriate line lengths. Visual proximity creates cognitive grouping even without explicit borders.

5. Postel’s Law

Core Concept: Be strict with output; flexible with input.

Accept varied user inputs while maintaining reliable, accessible interfaces. Translate non-standard input to meet requirements and provide clear feedback.

6. Peak–End Rule

Core Concept: Users judge experiences by their peaks and conclusions.

Focus on the most intense moments and final touchpoints. Remember that negative experiences create stronger memories than positive ones. Journey mapping helps identify emotional peaks.

7. Aesthetic–Usability Effect

Core Concept: Beautiful design masks usability problems.

Users form website opinions within milliseconds, with visual appeal as primary factor. This effect can hide usability issues during testing; ask probing questions to uncover real problems.

8. von Restorff Effect

Core Concept: Distinct items are remembered better than similar ones.

Use restraint with emphasis to prevent visual competition. Excessive emphasis causes users to ignore important information or perceive noise rather than signal.

9. Tesler’s Law

Core Concept: Inherent system complexity cannot be eliminated, only shifted.

Complexity transfers between development/design and user interaction. Simplification to abstraction removes necessary information for informed decisions.

10. Doherty Threshold

Core Concept: Responsiveness requires interactions under 400ms.

Enhance perceived performance through skeleton screens, progress indicators, blur-up techniques, and optimistic UI. Deliberate delays can increase perceived value and trust.