Design of Everyday Things - Norman, Don [110]
EASY LOOKING IS NOT NECESSARILY EASY TO USE
Early in POET I examined the modern office telephone, simple looking but hard to use. I contrasted this with an automobile dashboard that has more than a hundred controls, complicated looking but easy to use. Apparent complexity and actual complexity are not at all the same.
Consider a surfboard, ice skates, parallel bars, or a bugle. All are simple looking. Yet years of study and practice are required to be good at using any of these objects.
The problem is that each of the apparently simple devices is capable of a wide repertoire of actions, but because there are few controls (and no moving parts), the rich complexity of action can be accomplished only through a rich complexity of execution by the user. Remember the office telephone system? When there are more actions than controls, each control must take part in a variety of different actions. If there are exactly the same number of controls as actions, then, in principle, the controls can be simple and the execution can be simple: find the correct control and activate it.
Actually, increasing the number of controls can both enhance and detract from ease of use. The more controls, the more complex things look and the more the user must learn about; it becomes harder to find the appropriate control at the appropriate time. On the other hand, as the number of controls increases up to the number of functions, there can be a better match between controls and functions, making things easier to use. So the number of controls and complexity of use is really a tradeoff between two opposing factors.
How many controls does a device need? The fewer the controls, the easier it looks to use and the easier it is to find the relevant controls. As the number of controls increases, specific controls can be tailored for specific functions. The device may look more and more complex, but it will be easier to use. We studied this relationship in our laboratory. 7 Complexity of appearance seems to be determined by the number of controls, whereas difficulty of use is jointly determined by the difficulty of finding the relevant controls (which increases with the number of controls) and difficulty of executing the functions (which may decrease with the number of controls).
We found that to make something easy to use, match the number of controls to the number of functions and organize the panels according to function. To make something look like it is easy, minimize the number of controls. How can these conflicting requirements be met simultaneously? Hide the controls not being used at the moment. By using a panel on which only the relevant controls are visible, you minimize the appearance of complexity. By having a separate control for each function, you minimize complexity of use. It is possible to eat your cake and have it, too.
Design and Society
Tools affect more than the ease with which we do things; they can dramatically affect our view of ourselves, society, and the world. It is hardly necessary to point out the dramatic changes in society that have resulted from the invention of today’s everyday things: paper and pencil, the printed book, the typewriter, the automobile, the telephone, radio, and television. Even apparently simple innovations can bring about dramatic changes, most of which cannot be predicted. The telephone, for example, was widely misunderstood (“Why would we want one? Who would we want to talk to?”), as was the computer (fewer than ten were thought to be sufficient to satisfy all of America’s computing needs).8 Predictions of the future of the city were widely off the mark. And nuclear power was once thought destined to lead to atomic automobiles and airplanes. Some people expected private air transportation to become as widespread