Computers and Society

David D, Thornburg, Associate Editor

Humanizing The User Interface, Part 1

Computers should be easy to use. Somehow this seems an obvious requirement for a product, yet many computer users are frustrated at the cumbersome nature of the programs they use day in and day out.

In previous columns, I've argued the case that computers should be transparent to their users—that the computer should disappear into the background, freeing the user to interact directly with the application. A key to transparent computing is the user interface— the vehicle through which the user interacts with the computer. The user interface has three components—input, output, and content.

Input generally involves the communication of physical motion from the user to the computer, signaling the computer to perform various activities. Typing on a keyboard, speaking into a microphone, or drawing a line with a finger on a touch tablet are all ways of using physical movement to convey information to a computer.

Output consists of messages communicated from the computer to the user's senses. The most often-used sense is vision—usually the screen display.

Content is the purpose of the computer activity—the management of text, the computation of spreadsheets, or the creation of graphic images, to name just a few. Although input flows from the user to the computer, and output goes from the computer to the user, the communication of content is purely inferential. In other words, the user has an internal model of what the computer program is doing, or how it is doing its task. To use a program successfully, it's not important if the user's model of what is happening is accurate. All that's important is if the model is consistent with the program's behavior.

Joy Or Pain

When we're working with a program that has a well-balanced user interface, computing is a joy. When the user interface is bad, we may think that computing just isn't worth the effort.

Fortunately there are a few good programs available that show how easy computers can be to use. Most users of The Print Shop (from Brøderbund) would agree that this product is wonderfully easy to use. Many people probably haven't read the instruction manual. This product also has good input and output interfaces that step the user through the creation of customized greeting cards, posters, banners, calendars, etc. This product is one of the top sellers of all time, so the role of a good user interface cannot be underestimated.

Quite often, software designers try to make their products easy to use by designing them to work with a modern input device like a mouse or touch tablet. Unfortunately, this isn't enough. For a computer application to appear transparent, the input, output, and content of the system must be meshed to create a combined ambience that is both natural to the user and appropriate to the task at hand. For example, any attempt to design input devices independently of the applications that use them is risky at best. A program that lets numbers be entered with a joystick may be appropriate for a game in which the joystick is used to select the number of players, but it is clearly the wrong approach for a financial analysis package that requires almost constant entry and update of numbers.

One reason I invented the KoalaPad was to make computers easier to use. Yet input devices like the KoalaPad are not enough by themselves. They can play an important role only when their use is a complementary part of the design of the whole product. This is why some people are frustrated by the Macintosh—not all Mac software is easy to use. It's true that this computer (and the Amiga) is capable of supporting tremendously powerful and easy-to-use software; but it's also true that many programs fall short in this important area.

It's hard to design a good user interface. Millions of dollars went into the research at Xerox that led to the desktop metaphor—the use of windows and pop-up menus that are now becoming commonplace. It took a heavy investment to bring the KoalaPad and Muppet Learning Keys to market. The cost of developing a good program for a personal computer can easily exceed $100,000. (Remember this the next time you think software costs too much!)

As difficult as this task may seem, those of us involved with computer software development owe it to our customers to make ease-of-use our top priority. The market slump of 1984 and 1985 showed that the public is unwilling to blindly accept everything thrown its way.

Next month we'll explore one model of human behavior that provides valuable clues in the search for the best user interfaces.