Design of Everyday Things - Norman, Don [36]
Knowledge from the world is usually easy to come by. Designers provide a large number of memory aids. The letters on the typewriter keyboard are one example. The lights and labels on controls act as external memory aids, reminding the user of the purpose and state of the control. Industrial equipment is replete with signal lights, indicators, and other reminders. We make extensive use of written notes. We place items in specific locations as reminders. In general, people structure the environment to provide a considerable amount of the information required for something to be remembered.
Many people organize their lives in the world, creating a pile here, a pile there, each indicating some activity to be done, some event in progress. Probably everybody uses such a strategy to some extent. Look around you at the variety of ways people structure their rooms and desks. Many styles of organization are possible, but the physical arrangement and visibility of the items frequently convey information about relative importance. Want to do your friends a nasty turn? Do them a favor-clean up their desks or rooms. Do this to some people and you can completely destroy their ability to function. 2
GREAT PRECISION IS NOT REQUIRED
Normally, people do not need precise memory information. People can remember enough to distinguish one familiar coin from another although they may be unable to remember the faces, pictures, and words on the coins.3 But make more precise memory necessary and you get havoc. Three countries have rediscovered this fact in recent years: the United States, when it introduced the Susan B. Anthony one-dollar coin; Great Britain, when it introduced the one-pound coin; and France, when it introduced a new ten-franc coin. The new U.S. dollar coin was confused with the existing twenty-five-cent piece (the quarter), and the British pound coin was confused with the existing five-pence piece. (The one-pound coin has the same diameter as the five-pence piece, but is considerably thicker and heavier.) Here is what happened in France:
“PARIS ... ” With a good deal of fanfare, the French government released the new 10-franc coin (worth a little more than $1.50) on Oct. 22 [1986]. The public looked at it, weighed it, and began confusing it so quickly with the half-franc coin (worth only 8 cents) that a crescendo of fury and ridicule fell on both the government and the coin.
“Five weeks later, Minister of Finance Edouard Balladur suspended circulation of the coin. Within another four weeks, he canceled it altogether.
“In retrospect, the French decision seems so foolish that it is hard to fathom how it could have been made.... After much study, designers came up with a silver-colored coin made of nickel and featuring a modernistic drawing by artist Joaquim Jimenez of a Gallic rooster on one side and of Marianne, the female symbol of the French republic, on the other. The coin was light, sported special ridges on its rim for easy reading by electronic vending machines and seemed tough to counterfeit.
“But the designers and bureaucrats were obviously so excited by their creation that they ignored or refused to accept the new coin’s similarity to the hundreds of millions of silver-colored, nickel-based half-franc coins in circulation ... [whose] size and weight were perilously similar.”4
The confusions probably occurred because the users of coins formed representations in their memory systems that were sufficiently precise only to distinguish among the coins that they actually had to use. It is a general property of memory that we store only partial descriptions of the things to be remembered, descriptions that are sufficiently precise to work at the time something is learned, but that may not work later on, when new experiences have also been encountered and entered into memory. The descriptions formed to distinguish among the old coins