What if the interviewee starts asking specific questions about your product? Especially if she is highly motivated to solve this problem, she will be eager to see what you’re building. You may or may not have a product in progress, but in any case, it’s best not to show the interviewee your product or talk about specifics until the very end of your conversation. Better yet, schedule a separate interview for talking about solutions.
Why is it a bad idea to show your product at this stage? The reason is that images or tangible specs will taint everything that your interviewee was going to say. Instead of thinking about how she works and her frustrations, she will subconsciously tailor her answers based on your product. (This is a variation on the “If you have a hammer, everything looks like a nail” principle.)* If an interviewee is eager to see your product or visuals first, you can explain that you’d like to hear about her experiences and frustrations first so that she’s not influenced by what already exists.
You can always offer to schedule a follow-up demo in the future, but once you’ve shown something, you’ll never be able to go back and get pure feedback from this person. If you don’t have anything to show yet, it’s OK to say so. You can say something like “We are hoping to solve the problem of people managing their personal finances, and in order to do that really well we need to first understand exactly what people are doing today and where they are struggling.”