Many times during the course of customer interviews, some ideas or concepts begin to emerge based on what the customers have told you thus far.
Many times, it is possible to take the information you have learned so far and begin to make drawings, sketches, screen mock-ups, or models made from wood, stereo lithography, or 3D printing models. This helps to crystalize what you have heard so far and also provides a basis for further market research. At this point, it is often helpful to add a section to the visit agenda at the completion of the interview to test some of these new concepts with customers to see how well they might fit their needs.
The purpose of concept testing, then, is to help predict the success of a new idea or concept before it enters the design stage, where real money and resources are allocated by getting customer reactions to the proposed offering. In my experience, I have found that customers will have a much easier time pointing to a concept that you already...