A New Metaphor

A good way to make human-machine interaction more natural would be to develop a better metaphor. A computer metaphor is a familiar object or activity that your computer imitates with its commands, display arrangements, and behavior. The two main metaphors we have today are the desktop and the browser. In the desktop metaphor, the display screen mimics a typical desk; information is kept inside folders, which can be opened, closed, and slipped into other folders. With Web browsing, the metaphor is downtown window shopping; you gaze at various “storefronts,” see one you like, and (click) you enter. Inside, there are more options to browse, you choose another, and again you enter. Like a linguistic metaphor, the power of a good computer metaphor is that it makes a new system you don’t know behave like an old “system” with which you are familiar. This lets you use the new system and get useful results out of it easily, since you don’t have to struggle learning new concepts and commands.

The desktop and browser metaphors are powerful, but glued together as they are in today’s machines, they make no sense because they work in different ways. Their makes claim they have to be different, since the operating system controls a computer while a browser controls a communications network. But that kind of excuse didn’t stop the telephone from looking and feeling the same to us, regardless of whether we make a local or a long-distance call, even though different equipment is involved in local and long-distance telephony.

We wouldn’t tolerate a telephone system that forced us to use one dialing procedure and keypad for local calls but a different procedure and keypad for long-distance calls. Yet we do with computers. We are forced to use the operating system’s desktop for “local” information on our own computer, and the browser for distant information on the Internet, even though we want to do the same things with information in both cases. Why confuse us with two different metaphors?

Human-centric computing demands that we merge the metaphors into a single system. A few developers are making cosmetic changes by adding a couple of features of one to the other. But no one is going beneath the surface to create a unified, single system. One reason for this is competition – rivals would have to cooperate or abandon a lucrative operating system or browser. Another reason is politics: The Justice Department’s two-year prosecution of Microsoft was built in part on charges that Microsoft was combining its Explorer browser with its Windows operating system which posed unfair competition for independent browser makers. It’s amazing that while we heard a great deal about every conceivable rivaling corporate interest, the far bigger human interest of ease of use was ignored. Even the judge’s Finding of Fact assumed that the division into browsers and operating systems was cast into concrete, ignoring the powerful “fact” that the boundaries between software systems should change to improve human utility.

But even a perfect system built from the ground up, one that captures what browsers and operating systems do today, wouldn’t be adequate. As we’ll see, there are many more things that our machines will do. And technology is advancing all the time, bringing new capabilities to the fore. Consider the millions of interconnected appliances that we will want to control. How will we “grab” them and “tell” them what to do? What’s going to be the metaphor? Giving them an address on the Web, as some manufacturers are beginning to do, and saying “Go get them,” is not enough. That’s like saying: “Everything in this world is in some physical location. Go get it.” Organizing these appliances according to what they can do will be more helpful.

The challenge for tomorrow’s systems builders is this: Find a new metaphor that captures not only what people can do with local and distant information, but also the new human-centric capabilities we want from machines in tomorrow’s computing terrain. Such a metaphor would go a long way toward making tomorrow’s systems easier to use.

One favorite and much-discussed metaphor is the assistant or servant. Think of your computer as an obedient servant that can understand your wishes and is familiar with your habits. You speak to it in your native tongue and it dutifully carries out your commands. Compelling, but a pipe dream. This puts us squarely in the domain of intelligent agents, which we do not know how to construct.

How about a virtual geographic metaphor? I favor this one because I dreamed it up……no doubt along with many other people. Information sites are organized as floors of various buildings, which sit along streets and avenues, aggregated into towns and cities, all shown on navigable maps on your screen. You zoom into and out of buildings, down alleys, across towns. The geographic mapping could be realistic, if you want to go to the Louvre, you navigate to Paris, and then to the museum. A more exciting prospect is to arrange your own information in a “virtual” map of your own creation. There could be a street of store you frequent, or a town known for its off-color sites. Shopping avenues might run north and south according to the category of goods sold – Foods Avenue, Clothes Avenue, Household Goods Avenue, Electronics Avenue, Music Avenue, and Books Avenue.

An interesting variation of this metaphor adds the notion of time. Moving your joystick forward, back, right, and left propels you north, south, east, and west, but pushing the joystick down takes you to the past of whatever site you are visiting, and lifting it up moves you to its future plans. Such a metaphor, which I have dubbed a “historicopter,” would be fantastic for studying the world, with every country contributing its history, current events, and futre plans to the experience via its Web sites.

To be complete, these geographic metaphors would have to be augmented with the actions that you could carry out on information, once you found it – for example, watch it, hear it, print it, change it, or run it as a program. Successful virtual information maps might be sold, traded, or given freely to people by organizations. They are technically straightforward to implement and would be easy to master, even for novice users, because moving in physical space, like talking and seeing, is a natural human experience with thousands of years behind it – a great asset for human-centric computing.

Other metaphors may be even better. Some people say we should have several metaphors, one for each occasion we use our machines. That’s technically pleasing, but not as economical and easy to remember as a single metaphor. Other people maintain we should liberate computers from metaphors altogether. They argue that tomorrow’s systems should be so natural and easy to use that they behave like the people, institutions, and objects we encounter every day. You just go out there and use them as naturally as you interact with people and things in the real world today. This is a seductive but unrealistic idea. Just to interact with other people you presume a level of intelligence on their part, which makes your interaction easy, but which, as we have seen, cannot be implemented by the machines.



Excerpts from “The Unfinished Revolution” by Michael Dertouzos