0.1.4 Why Focus on Design?

This book describes design processes that help to produce good interfaces. The focus on process instead of end result deserves some explanation. Why don't we simply describe what a good interface is and leave the reader to create interfaces that fit that description?

There are several reasons. An interface has to be matched to the task it will support, as well as to the users who will work with it. There is an infinite variety of tasks and users, so there's no simple definition of a "good" interface. There have been many attempts to give broad, general guidelines for good interfaces, but those guidelines are usually too vague to be of much use. For example, a general guideline might say, "Give adequate feedback." But how will the designer determine what's "adequate"?

More specific guidelines for elements of the final interface have also been developed, describing such elements as how menus should be designed, how to label icons, and so forth. These guidelines also have problems. It's impossible to cover every possible combination of task, user, and interface technology, so no set of specific guidelines can be complete. Even so, lists of specific guidelines are often so large and cumbersome that practicing designers find them very difficult to use. Further, in a given situation there are often several contradictory guidelines, and the designer has to rely on intuition to decide which are most important.

We might make an analogy between a designing a successful interface and a cutting a piece of string to the "right" length. General guidelines for the length of a piece of string, such as "long enough to do the job," aren't very helpful; and a list of specific definitions of the correct length for every purpose would be endless: 6 inches to tie up sagging flowers, 42 inches for a small package, 78 inches to tie down the trunk on an old VW, etc. But it's easy to describe a process that produces the right length: start with a very long piece of string, tie up your plant, package, car, or whatever, and then cut off the string that's not being used. Similarly, instead of specifying all the characteristics of the finished interface, this book present a design process that can produce good interfaces.

This is not to say that simply following the design process will magically produce a successful interface every time. The designer using the process must make many decisions along the way, relying on knowledge of users, their cognitive skills and limitations, and their tasks. In addition, the interface design process will only be successful if it is integrated into the software production process as a whole. This book presents basic information about all of these issues, and it contains pointers to other books and articles containing further useful information. All this material is organized in the context of the design process.