Design of Everyday Things [40]
How can we remember all these things? Most of us can’t, even with the use of mnemonics to make some sense of nonsensical material. Books and courses on improving memory can work, but the methods are laborious to learn and need continued practice to maintain. So we put the memory in the world, writing things down in books, on scraps of paper, even on the backs of our hands. But we disguise them to thwart would-be thieves. That creates another problem: How do we disguise the items, how do we hide them, and how do we remember what the disguise was or where we put them? Ah, the foibles of memory.
Where should you hide something so that nobody else will find it? In unlikely places, right? Money is hidden in the freezer, jewelry in the medicine cabinet or in shoes in the closet. The key to the front door is hidden under the mat or just below the window ledge. The car key is under the bumper. The love letters are in a flower vase. The problem is, there aren’t that many unlikely places in the home. You may not remember where the love letters or keys are hidden, but your burglar will. Two psychologists who examined the issue described the problem this way:
“There is often a logic involved in the choice of unlikely places. For example, a friend of ours was required by her insurance company to acquire a safe if she wished to insure her valuable gems. Recognizing that she might forget the combination to the safe, she thought carefully about where to keep the combination. Her solution was to write it in her personal phone directory under the letter S next to ‘Mr. and Mrs. Safe,’ as if it were a telephone number. There is a clear logic here: Store numerical information with other numerical information. She was appalled, however, when she heard a reformed burglar on a daytime television talk show say that upon encountering a safe, he always headed for the phone directory because many people keep the combination there.”11
All these numbers to remember add up to unwitting tyranny. It is time for a revolt.
THE STRUCTURE OF MEMORY
“Say aloud the numbers 1, 7, 4, 2, 8. Next, without looking back, repeat them. Try again if you must, perhaps closing your eyes, the better to ‘hear’ the sound still echoing in mental activity. Have someone read a random sentence to you. What were the words? The memory of the just present is available immediately, clear and complete, without mental effort.
“What did you eat for dinner three days ago? Now the feeling is different. It takes time to recover the answer, which is neither as clear nor as complete a remembrance as that of the just present, and the recovery is likely to require considerable mental effort. Retrieval of the past differs from retrieval of the just present. More effort is required, less clarity results. Indeed, the ‘past’ need not be so long ago. Without looking back, what were those digits? For some people, this retrieval now takes time and effort. ”12
Psychologists distinguish between two major classes of memory: short-term memory and long-term memory (abbreviated STM and LTM, respectively). The two are quite different. Short-term memory is the memory of the just present. Information is retained in it automatically and retrieved without effort; but the amount of information that can be retained this way is severely limited. Something like five to seven items is the limit of STM, with the number going to ten or twelve if a person also rehearses, mentally repeating the items to be retained. Short-term memory is invaluable in the performance of everyday tasks, in letting us remember words, names, phrases, and parts of tasks. It acts as a working or temporary memory. But the memory is quite