Don't use low-fidelity prototypes to test desirability
Low fidelity paper prototypes and wireframes are great for feedback on usability, but realistic looking high-fidelity prototypes like mock screencasts are much more effective at assessing desirability of new products.
Designers and product managers are often encouraged to test concepts with rapid, low-fidelity prototyping techniques. Paper prototyping and wireframing are encouraged not only because these prototypes can be made and changed quickly, but also because they encourage viewers to express critical feedback:
By conveying the message that I was knocked off in a matter of minutes, if not seconds, the sketch says, “I am disposable, so don’t worry about telling me what you really think, especially since I am not sure about this myself” — Bill Buxton, Sketching User Experiences (106).
I’ve found this to be true for assessing usability and information architecture. However, when testing whether a concept is desirable to users I’ve found that low-fidelity prototypes are much less likely to provide accurate results. People want to be nice - when a product concept is presented as a “disposable” hypothetical design, it’s easy for a potential customer to say “yeah I’d pay $10/month for that” or “sure I’d use it every week,” regardless of how they would actually react to the finished product.
In contrast, a prototype that appears to be an actual product lets you confront the potential customer with a real choice: do they want to buy the product today, or not? While an idea might test positively when presented as a hypothetical, the same concept presented as a real choice might unearth all sorts of objections and polite declines. As a result, the high-fidelity prototype will assess desirability more authentically: hearing “it’s a neat idea but we don’t have budget at this point” or “we would consider it, but we’d need X,Y, & Z features first” are the sort of crucial signals around product-market fit that you can only get from confronting potential customers with what appears to be a real choice.
One of my favorite techniques for testing desirability of brand new product is the mock screencast: after creating realistic-looking pages using Web Inspector or your favorite design tool, you can then record your screen while “navigating” through the site by tabbing through mockups and narrating the value proposition. In an afternoon, you can create a 90-second pitch video, share it with prospective customers as if it were a finished product, and get authentic feedback on whether customers want your product. Here’s an example we created when testing desirability for a concept we called “Clever Menus”. Other effective high-fidelity, desirability testing techniques include spoof landing pages and fake door tests.
Once you’re confident in the desirability of the product, you should leverage low-fidelity prototyping methods like wireframes and paper prototypes to make the product easy to use and understand. But to get authentic feedback on desirability, you need a high-fidelity prototype to confront potential customers with a real choice.