Real customers are asked to re-create their activities using a low-fidelity mockup such as a paper prototype
By early testing of your ideas with real customers you will quickly come to realize what works well or not, and most importantly—why. Interviews with real potential users in your target population are conducted to test your ideas using interactive mockups such as paper prototypes, service concept boards, or physical models. Mockups are designed to be changeable on the fly and intentionally look unfinished, inviting the user to engage in constructive co-design of changes that can be made immediately.

Mockup interviews are conducted the same way as contextual inquiry discovery interviews, talking to real customers with the addition of manipulating the prototype as they use it to re-create their real-life activities. This way feedback is based on observed issues and the customer’s underlying intent to carry out their activity. Interviews are recorded and reviewed afterwards to identify and capture design issues. After each round of interviews, typically with 3-5 users, issues are mapped to the design to inform design changes. It typically takes two to three rounds of mockup testing to stabilize the design enough to build a more refined model such as a wireframe.