Unit 3 · Lesson 12 of 20
Prototype the decision you need to test
Choose prototype detail by the question and include the behavior needed for a useful test.
01 / Learn
The idea
A prototype is a tool for learning. Its detail should match the uncertainty: a paper flow may test sequence and wording, while timing, speech recognition, haptics, or physical reach require a more realistic simulation. High visual polish does not compensate for missing interaction behavior. Conversely, building a full product to test a label can waste time.
List what the prototype will represent, what it will fake, and which conclusions it cannot support. For a physical or voice interaction, simulate the environment as well as the interface: distance, noise, hands occupied, and recovery after failure. Give participants meaningful tasks, not a tour of the design. Plan how the facilitator will respond consistently when the prototype cannot truly run the service.
A beautiful high-fidelity prototype is automatically more valid. Fidelity is useful only in the dimensions needed for the decision.
02 / See the reasoning
Worked example
Fictional scenario
A team is deciding whether a voice-assisted appliance needs a physical cancel control.
To test whether people understand 'Cancel' after a voice command, an expert first uses a scripted speaker and a cardboard control in a noisy room. The prototype can reveal whether people attempt voice or physical cancellation and whether they recognize the result. It cannot establish production speech-recognition accuracy, so that remains a separate test.
Try a decision →03 / Decide
Guided decision
The decision is whether users can recover from a misheard voice command while their hands are occupied. Which first prototype is most informative?
Feedback on your choice
What could change the answer: If the specific uncertainty is speech recognition in noisy conditions rather than recovery behavior, a functioning recognition system becomes necessary.
This feedback helps you examine the decision; it does not grade your written reasoning.
Apply it somewhere new →04 / Apply elsewhere
Independent application
Fictional scenario
A public-service website team needs to know whether people understand eligibility before starting a long application.
Specify a low-cost prototype and task that test comprehension and decision to proceed. Name what the prototype can and cannot prove.
Make: A prototype brief with fidelity choices, scripted states, participant task, and limitation notes.
The prototype represents the behavior needed for the question and avoids claiming evidence about untested dimensions.
Unit complete
You completed design and apply.
You finished this unit's four independent tasks. The next unit builds on your judgment with a new capability.
05 / Keep working