H11 Domain-Appropriate Devices *

Every interactive software system has a domain in which it is used, or which it addresses, and that its contents or functions are about. The application domain of a computer-based drawing course, for example, is the artistic domain of drawing, and the application domain of a power plant process control system is that power plant with its functions.

However, most interactive systems have been using the standard keyboard and mouse as input devices, plus a monitor as output device, but nothing else. User interface designers put a lot of work into creating "metaphors" in which the virtual, on-screen world resembles items and concepts from the well-known, physical world. But all the while, those objects remain virtual, volatile images on a standard screen to be manipulated with the same, generic set of input devices and physical actions: type, point, click.

A claim that is often heard is that incorporating dedicated input and output devices is too expensive. But often, it is not even attempted to estimate the amount of extra work and its possible payoff, because it requires a lot of thinking from the designers to come up with new ideas apart from mouse and keyboard, and it is an area where products and standards are not as comfortably developed and accessible as in the world of standard input devices.
Figure: A domain-appropriate control to adjust a car seat [Norman, 1988].

But psychological research as well as common sense tell us that users are much more efficient, successful, and satisfied when they are offered I/O devices that resemble physical objects of the application domain. For example, Norman [1988, pp. 23 ff.] talks in detail about the advantages of "natural mappings" from input device to system function, and gives a good example of a device perfectly designed for its dedicated purpose: a car seat adjustment control that is shaped like a miniature seat itself. To adjust his own seat, the user simply pushes the corresponding part of the miniature seat into the desired direction. It would have been far more cumbersome to understand and use the seat controls if they had been designed as a set of industry-standard buttons on the dashboard (and, if we imagine using those controls ourselves, it would probably also have been less fun).

The same is true for the WorldBeat system shown in the opening picture: it is an interactive exhibit that demonstrates to its users how computers open up new ways to interact with music, from conducting a computer orchestra, to improvising to a blues band with computer support. While our initial designs included a standard keyboard and mouse as input devices, we gradually found out that we did not really need them, and that they would spoil the "musical atmosphere" that the exhibit tries to create. The two infrared batons, on the other hand, are artefacts that resemble a conductor's baton, or xylophone sticks - objects that are well known from the musical domain. In taking them up, the user is already led away from thinking about interacting with a computer, into an experience of interacting with music. The system was elected one of the three most popular exhibits in the centre where it is installed [Borchers, 1997], and received an award for its new way to convey musical concepts.