Design of Everyday Things - Norman, Don [37]
Suppose I keep all my notes in a small red notebook. If this is my only notebook, I can describe it simply as my notebook. If I buy several more notebooks, the earlier description will no longer work. Now I must call the first one small or red, or maybe both small and red, whichever allows me to distinguish it from the others. But what if I acquire several small, red notebooks? Now I must find some other means of describing the first book, adding to the richness of the description and thereby to its ability to discriminate among the several similar items. Descriptions need discriminate only among the choices in front of me, but what works for one purpose may not for another.6
THE POWER OF CONSTRAINTS
Back in the good old days of oral tradition (and even today for some cultures), performers traveled around reciting epic poems thousands of lines long. How did they do it? Do some people have huge amounts of knowledge in their heads? Not really. It turns out that external constraints exert powerful control over the permissible choice of words, thus dramatically reducing the memory load.
Consider the constraints of rhyming. If you wish to rhyme one word with another in English, there are usually ten to twenty alternatives. But if you must have a word with a particular meaning to rhyme with another, there are usually no candidates at all. And if there are any, in most cases there is only one. Combining the two constraints of rhyme and meaning can therefore reduce the information about the particular word that must be kept in memory to nothing; as long as the constraints are known, the choice of word can be completely determined. The learning of material like poetry is greatly aided by these kinds of constraints, which work on the general schema for the class of poem, meter, and topic.
Here is an example. I am thinking of three words: one means “a mythical being,” the second is “the name of a building material,” and the third is “a unit of time.” What words do I have in mind? Although you can probably think of three words that fit the descriptions, you are not likely to get the same three that I have in mind. There simply are not enough constraints.
Now try a second task, this time looking for rhyming words. I am thinking of three words: one rhymes with “post,” the second with “eel,” and the third with “ear.” What words am I thinking of?
Suppose I now tell you that the words I seek are the same in both tasks: What is a word that means a mythical being and rhymes with “post”? What word is the name of a building material and rhymes with “eel”? And what word is a unit of time and rhymes with “ear”? Now the task is easy: the joint specification of the words completely constrains the selection.
In the psychology laboratory, people almost never got the correct meanings or rhymes for the first two tasks, but they correctly answered “ghost,” “steel, ” and “year” in the combined task almost always. 7
The classic study of memory for epic poetry was done by Albert Bates Lord. He went to Yugoslavia and found people who still followed the oral tradition. He demonstrated that the “singer of tales,” the person who learns epic poems and goes from village to village reciting them, is really recreating them, composing poetry on the fly in such a way that it obeys the rhythm, theme, story line, structure, and other characteristics of the poem. This is a prodigious feat, but it is not an example of rote memory. Rather, the practice illustrates the immense power of the multiple constraints that allow the singer to listen to another singer tell a lengthy tale once, and then (after a delay of a few hours or a day) apparently recite “the same song, word for word, and line for line.”8 In fact, as Lord points out, the original and new recitations are not the same word for word. But the listener would perceive them as the same, even if the second version were twice as long as the first. They are the same in the ways that matter