design-5-act-user-interview-testing

Run five 60-minute 1-on-1 interviews following the 5-act structure: friendly welcome, context questions about current workflows, prototype introduction with a scenario, task observation with neutral think-aloud prompts, and a quick debrief covering value and pricing.

Five users is the standard, based on Jakob Nielsen's 5-user rule showing that five participants uncover roughly 85% of usability and concept flaws. This makes five interviews sufficient for detecting high-confidence patterns in a sprint.

A pattern scorecard is a color-coded matrix where each observation per test step is marked green for validated, red for friction or rejection, and yellow for mixed signals. Scanning columns vertically across five users reveals which prototype steps work and which fail.

Do not use it for automated headless browser tests, quantitative A/B experimentation analytics, or storyboarding and prototyping work. It is designed specifically for live qualitative interviews on an existing interactive prototype.

Use neutral, non-directive probing prompts such as asking what the participant expected to happen, never defend or explain the prototype, and never ask leading questions. The 5-act protocol structures each phase to keep interviewer bias out of the evidence.