Design of Everyday Things [44]
We searched for another explanation. Perhaps it wasn’t a design feature, after all. Perhaps it was an accident of design. Perhaps turning on the lights and pulling back on the stalk connected the electrical power to the car, overriding the fact that the ignition key was off. This would allow the sunroof to work, but only as a by-product of the way the lights were wired.
This model was more specific. It explained what was happening and allowed us to predict that all electrical items should work. So we checked. Turning on the light switch without engaging the ignition did not turn on the headlights; only the parking lights went on. But when we also pulled back on the turn-signal stalk, the headlights did turn on, even though the ignition was off. With the stalk pulled back, the sunroof would close and open. The windows would close and open. The fan on the heating system worked. So did the radio. This was an effective mental model. Now we could understand better what was happening, predict new results, and more easily remember the peculiar set of operations required for the task.
Memory Is Also Knowledge in the World
As we have seen, knowledge in the world, external knowledge, can be very valuable. But it, too, has drawbacks. For one, it is available only if you are there, in the appropriate situation. When you are somewhere else, or if the world has changed meanwhile, the knowledge is gone. The critical memory aids provided by the external information are absent, and so the task or item may not be remembered. A folk saying captures this situation well: “Out of sighf, ouf of mind.”
REMINDING
One of the most important and interesting aspects of the role of external memory is reminding, a good example of the interplay between knowledge in the head and in the world. Suppose a neighboring family asks you to take them to the airport. You agree to take them next Saturday at 3:30 P.M. Now the knowledge is in your head, but how are you going to remember it at the proper time? You will need to be reminded. There are many strategies for reminding. One is simply to keep the information in your head. If the event is important enough, you count on having it come repeatedly to mind—what psychologists call rehearsal—so that you can simply assume that there will be no difficulty at all remembering when to leave on Saturday. You can keep the information in your head especially when the event is of great personal importance: suppose you are catching the plane for your first trip to Paris. You won’t have any problem remembering. But keeping the knowledge in your head is not ordinarily a good reminding technique.
Suppose the event is not personally important. it is several days away, and you are leading a very busy life. Now you’d better transfer some of the burden of remembering to the outside world. Here is where you use notes to yourself, or pocket and desk calendars or diaries, or electronic alarm clocks that can be set for time of day and date. Or you can ask a friend to remind you. Those of us with secretaries put the burden on them. They, in turn, write notes, enter events on calendars, or set an alarm on the computer system (if it is well enough designed that they can figure out how to work it).
A good reminding method is to put the burden on the thing itself. Do my neighbors want me to take them to the airport? Fine, but they have to call me up the night before and remind me. Do I want to remember to take a book to the university to give to a colleague? I put the book someplace where I cannot fail to see it when I leave the house. A good spot is against the front door of the house. I can’t leave without tripping over the book. If I am at a friend’s house and I borrow a paper or a book, I remember to take it by putting my car keys on it. Then when I leave,