T. Lmdauer, The Trouble with Computers: usefulness, usability. and productivity, The MIT Press, Cambridge, 1995, Chapter 6, pp. 141-168. Usefulness and Usability Usefulness Upscale's department store installed a checkout machine intended for better inventory control and customer service. The screen showed a menu of items for sale. It started with a list of general categories: housewares, men's clothing, and so forth, each represented by a colorful picture, an icon. Choose an icon by touching it with your finger, and up comes a more detailed list-sport clothes, suits, shoes . . . each represented by another colorful icon. And on down to the individual item type. No longer did clerks need to know or enter the item type or number-so long as their interpretation of the icons and categories matched that of the designer. I once tried to buy some candles. Three clerks struggled for fifteen minutes to enter the sale. Candles were under vases under platters under mixers under chairs.' It's easy for a computer to offer operations that don't help people. For example, computer schemes for finding books in libraries and for pres- enting them electronically make it harder to find the books and harder to read them. Later we'll see how dumb applications have been turned around by user-centered design. For now, let's look at some of the under- lying problems. Phase one computer applications perform the same task that a human might otherwise do. Programming for these applications demands near- perfect understanding of what the task is and how it can be accom- plished. In tasks like bookkeeping and gun aiming there are well-defined142 Whd's Wrong with Them Usefulness and Usability 143 formuids by which the task can be performed, principles that humans would tollow preciscly if they could. These can be translated directly into computer programs. It has been said that the first industrial revolution replaced human and animal muscle with more efficient energy sources and that the information revolution is replacing human mental work with more efficient electronic processes. That's the way phase one appli- cations works. Phase one computing has had two effects. First, it has pushed forward the replacement of human motor skills with more accu- rately controlled mechanical ones. Second, it has largely replaced humans in simple acts of arithmetic and filing. Arithmetic is an easily described skill and one at which no mathematical John Henry would stand a chance. The second phase of computer application, helping people think, is surprisingly more difficult. Note how shallow are the components of writing assumed by word processors, how superficial the aspects of busi- ness decision making taken on by spreadsheets. The mental processes of composing memos and documents, of making medical and business decisions, of negotiating and persuading, of formulating plans, and com- municating ideas will not soon be captured and imprisoned in a machine. No one really knows how humans do these mysterious things.2 Humans have amazing memories from which details can be recalled in response to any hint about any part of the original experience. (What time did your childhood neighbors eat dinner on Christmas?) People have as- tounding visual and auditory pattern-recognizing ability, can easily iden- tify one among a hundred thousand faces or words. In reading text, a literate adult can guess a missing from context half the . And these are paltry feats compared to what goes on in the mind during the comprehension, appreciation, or creation of a serious (or funny) verbal passage. No matter what you may have read in an airline magazine, we can't yet come close to these human abilities in any programmable pro- cess. In services, the role of the computer is to help people help people. Thinking how to do this has proved more difficult than technologists expected. Upscale's worthless point-of-sales device is worse than most others perhaps, but so far not enough are good enough. Reservation and information retrieval systems help people do some important business chores more easily. So do bar code inventory systems, income tax prepa- ration programs, email, and several dozen more. But most department store service has gotten worse since computers; so has the handling of telephone inquiries and dozens more. Figuring out really good things to do with computers in service businesses is difficult. Usability 1 tried to change a character in the bibliography of this book to put in a French diacritical mark. After an hour of reading three manuals (for the text editor, the bibliography program, the bibliography program's en- hancement package) and many experiments, I gave up. 1 hope the Acadi- rnie Fran~ais will forgive me. A phase two system is unlikely to be useful unless it is easy to operate, although the opposite is possible: a system that is easy to operate but of no value. The division between usefulness and usability is sometimes fuzzy; one can't tell whether a system flunks for one reason or the other. Was the Upscale department store's menu a failure because it was hard to use or because it wasn't useful? Or was it useless because it was hard to use? Nevertheless, usability is the key issue in thousands of cases. In a sys- tem in which you sometimes enter K to "keep" a program and in other cases enter K to "kill" the same program, there is a usability problem no matter how useful the program might otherwise be. Because different programs are written by different programmers at different times and marketed by different companies, such inconsistencies are rife. Even when companies like Apple, and more recently IBM and others, attempt to set up interface consistency standards, they don't always have the de- sired effect. Sometimes it's impossible to maintain consistency as the functions of a system multiply. Bruce Tognazinni, Apple's erstwhile hu- man interface evangelist, has written, "The Macintosh promises consis- tency, and it is a promise that is dreadfully hard to keep" (Tognazzini 1992). The Macintosh user interface guidelines say the menu bar (a strip along the top of the screen from which available actions can be chosen by a mouse click) must always be visible. But here comes a program144 What's Wrong