Rettig aims to encourage the reader to try paper prototyping during formative evaluation of user interfaces. Such “lo-fi” prototyping can be done with simple artist’s supplies and, the author argues, allows both designer and user to concentrate on deeper design issues than just colors or fonts, such as the conceptual metaphor of the overall design. Even computer-supported prototyping tools, he further argues, tend not to work well for generating design ideas because they tend to create design inertia in developers. Rettig argues, finally, that until you try this method, you will not be convinced of its real value.

I would argue that such tools are both good and bad for design brainstorming, because they take time for someone to “play computer” in response to a user’s intended action. The reason that they are good is that, while the state of the paper prototype is being changed, the user and the designer can reflect on other possibilities, and such reflection is standard practice in design studios. On the other hand, not all interfaces are equally suitable to such an approach, and the author fails to point this out. Because the user does not actually use an input device or see a display, the dynamic characteristics of either, or their interaction, are not simulatable. For example, how can the person playing computer simulate the hand-eye coordination of a pointing device or the motion of a dynamic display? I suspect it would be difficult to hand-simulate, for example, the active icons of the Dynavox speech synthesizer, which, when turned on, present an extremely distracting array of visual noise to the user, causing most users to leave them turned off.

Despite these criticisms, I strongly urge interface designers to read this paper, especially for the excellent discussion of the dynamics and politics of user testing. Students of interface design ought to be required to use this approach not only because of its value, but also because it causes them to focus on the issues rather than on the technology.