Case Studies - Paper Prototyping: The Fast and Easy Way to Define and Refine User Interfaces - page 36

The textured control buttons consisted of six rectangles along the bottom edge, left- and right-pointing
triangles near the center about an inch apart, and up- and down-pointing triangles along the right edge.
To add texture, the students used a clear plastic overlay and damaged the plastic over the buttons by
poking it with a pen. In some modes, there were two textured rectangles per touch screen button. For
example, on the screen shown in Figure 2.9 , the user would feel two textured buttons for the "By Band"
control, but both would do the same thing. This flexible mapping of physical to virtual buttons allowed
the virtual buttons to be larger on screens where fewer buttons were needed.
Figure 2.9: These two prototype screens illustrate different uses of the display area and textured
buttons. The left image shows the radio display, where the six buttons were used in a conventional
manner for preset stations. The right image shows the jukebox, where the three bottom virtual
buttons each include two textured buttons.
Successful Interface, Successful Learning Experience
The students conducted five usability tests of their prototype. They placed each screen inside a clear
plastic sleeve like those used for overhead transparencies. They put all the screens into a three-ring
binder so that whichever of them was playing Computer could flip to the next screen based on user
actions. The user sat at a PC-based driving simulator, and one student held the prototype off to the
side, about where it would be in a car.
The students actually did their first usability test in a car driven slowly around a parking lot.
Professor Kiesler decided that was a little too realistic and stipulated that for safety reasons,
prototypes were to be tested without driving.
Sam and Kristin observed that people did use the textured buttons as they had hoped. The users were
able to keep their attention primarily on driving and still operate the controls correctly. Even with only
five users, there was a consensus that users wanted some additional functionality, such as a "profile"
feature to store preferences for sound levels, temperature, and radio presets. The students also
learned that some features they had considered (such as playlists) were either not important to users or
were not practical without a keypad, which would be inappropriate to use while driving. The feedback
from their paper prototype quickly revealed which of their ideas were workable and which were not.
Because this paper prototype was created in academia rather than in industry, its success is measured
not only by how well the interface worked but also by how much the students learned from it. In addition
to the basics of touch screen design, Sam and Kristin gained experience in balancing design
constraints. The small display size forced them to keep simplifying the functionality and interface, and
the paper prototype let them experiment with ways to make the most common functions the easiest to
use.