/usability-testing

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

1. **Welcome** — explain what you're testing (the design, not them) 2. **Background** — 2-3 questions about their relationship to the problem 3. **Tasks** — present each scenario one at a time, observe silently 4. **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`