| name | usability-testing |
| description | Use when planning or conducting usability tests — writing test scripts, defining tasks, selecting participants, analysing findings, and turning observations into design actions |
Usability Testing
Testing with real people is how you find out if the design works — not by looking at it, but by watching someone use it.
When to Use
- After design-builder produces a working prototype
- Before declaring a design complete
- When the design-critic flags persona coverage gaps
- When assumptions about user behaviour need evidence
Process
Step 1: Define What You're Testing
Write 3-5 task scenarios that map to the core jobs in the brief. Each task:
- Starts with a realistic trigger — "You just bought a new plant and want to add it to the app"
- Has a clear success condition — "The plant appears in your list with a watering schedule"
- Does not tell the user how — never say "tap the + button"
Step 2: Select Participants
Recruit 5-8 participants. At minimum include:
- 1 person who uses a screen reader
- 1 person over 60
- 1 person who is not a native speaker of the interface language
- 1 person with low tech confidence
Reference inclusive-personas for the ability spectrum.
Step 3: Choose Method
| Method | When to use | Minimum participants |
|---|
| Moderated think-aloud | New flows, complex interactions | 5 |
| Unmoderated remote | Simple tasks, large sample | 8-12 |
| Guerrilla (hallway) | POC validation, time-constrained | 3-5 |
| Accessibility audit with AT users | After build, before ship | 2-3 |
Step 4: Write the Test Script
- Welcome — explain what you're testing (the design, not them)
- Background — 2-3 questions about their relationship to the problem
- Tasks — present each scenario one at a time, observe silently
- Debrief — "What was hardest?" "What would you change?"
Never help during a task. Silence is data.
Step 5: Analyse Findings
Classify outcomes per task:
- Completed easily — no hesitation, no errors
- Completed with difficulty — hesitation or errors but recovered
- Failed — could not complete
- Completed wrong — thought they succeeded but didn't
Severity: Critical (blocks 2+ participants), Major (significant difficulty), Minor (noticed but not impeding).
Step 6: Turn Findings Into Actions
Every finding becomes a design action: "[Severity] [What happened] → [Design action] → [Which agent handles it]"
What You Deliver
- Task success rates table
- Ranked findings by severity
- Design actions with agent assignments
- Recommendation: iterate / ship / rethink
Integration
- Informed by:
inclusive-personas, design-discovery
- Feeds into:
design-lead, design-builder, design-strategist
