UX Principles & Heuristics

UX Principles & Heuristics

The evaluation backbone. Every design review should walk these.

Nielsen's 10 heuristics (operationalized)

1. Visibility of system status — every action gets feedback within 100ms; loading >1s shows progress; background work shows state (saving…/saved).
2. Match to the real world — user vocabulary, not system vocabulary; natural ordering; familiar metaphors.
3. User control & freedom — undo > confirm; back always works; easy exit from every flow; cancel long operations.
4. Consistency & standards — internal consistency (one pattern per job) and platform conventions (don't reinvent share/back/tabs).
5. Error prevention — constraints over corrections: good defaults, disabled-invalid combinations explained, confirm irreversible, autosave.
6. Recognition over recall — show options, don't make users remember codes/paths; recently-used surfaces; visible state.
7. Flexibility & efficiency — shortcuts for experts (keyboard, gestures, command palette) that stay invisible to novices; smart defaults for everyone.
8. Aesthetic & minimalist design — every element competes for attention; cut what doesn't serve the current task.
9. Help users recognize & recover from errors — plain-language errors: what happened, why, what to do; preserve user input.
10. Help & documentation — contextual help at point of need (tooltips, inline hints) beats manuals.

Behavioral laws to apply

• Fitts's Law: important targets = big and close. Thumb zone on mobile (bottom half); screen edges/corners on desktop are "infinite" targets.
• Hick's Law: decision time grows with options. Progressive disclosure; recommended defaults; 3-tier pricing not 7.
• Jakob's Law: users spend most time on other sites — meet conventions, spend novelty budget only on your core differentiator.
• Miller's Law / chunking: group into 5–7 chunks (phone numbers, card numbers, nav sections).
• Peak–end rule: invest in the flow's peak moment and its ending (success states, confirmations, celebrations).
• Von Restorff: the one visually-different element gets remembered — that's why one primary CTA works.
• Doherty threshold: keep system response <400ms to keep users in flow; use optimistic UI where safe.
• Goal-gradient: show progress; users accelerate near completion (progress bars start pre-filled ~10%).
• Tesler's Law: complexity is conserved — absorb it in the system (autodetect, defaults) rather than pushing to users.

Cognitive load rules

• One primary job per screen. Screens that do everything do nothing.
• Progressive disclosure: advanced options behind "Show more"; wizard steps over mega-forms.
• Defaults do the work: 90% of users never change them — make defaults the recommended path.
• Blank-slate anxiety: never open on an empty canvas without a starting template/example.

Feedback timing budget

Skeletons beat spinners for content layout; optimistic UI (assume success, reconcile on failure) beats both for social actions.