User interface stories from the real world

've finished my series of articles on tensor algebra and am working on a new series on pixel arithmetic, but to clear the palate I thought I would tell a few personal stories about user interfaces in the real world. User interface design is closely associated with the field of computer graphics. In fact, the annual Siggraph conference was originally called the " Conference on Computer Graphics and Interactive Techniques. " Those of us who deal with user interfaces tend to think primarily in terms of computer programs. But user interface problems in the real world are often worse since the real world is not nearly as malleable as the computer world. An ideal solution, even if we know what it is, might not be practical to implement. In my youth I used to hate gym class. But now I find that I need to go to the gym three times a week and work out just to keep my body from falling apart. The sports club I belong to is very nice and has recently been remodeled to make it even nicer. There are some glitch-es, however. Most of the lockers in the locker room are the first-come, first-served type. For each trip you would find an unused locker and use it for the duration of that trip. Originally, once you had changed into your exercise togs, you would insert your membership card into a slot in the door that would release a physical key that you use to lock the door. You pin the key to your gym shorts and go to various activities like pushing levers, turning cranks, and climbing the stairway to nowhere. When done working out, you would go back to whatever locker you used and unlock it with the key pinned to your clothes. The key would then stay in the door ready for the next patron. An important feature of this mechanism is that the key had the locker number engraved on it. This is what Donald Norman would call " information in the world " (see The Design of Everyday Things, Basic Books, 1988). The remodeled lockers have fancy electronic locks. You find an unused locker, change clothes, and then type in a four-digit number of your choosing into the door's electronic keypad. The locker would store this number and lock itself. You proceed to the exercise studio and climb, push, and …