CHAPTER XV
ASSOCIATION AND MENTAL IMAGERY
SOMETHING ABOUT THINKING AS RELATED TO MEMORY
Memory plays a part, not only in "memory work", and not only in remembering particular past experiences, but in all sorts of thinking. Recall furnishes the raw material for thought. A large share of any one's daily work, whether it be manual or mental, depends on the recall of previously learned reactions. Most of the time, though we are not exactly trying to remember facts committed to memory, we are recalling what we have previously learned, and utilizing the recalled material for our present purposes. For example, in conversation we recall words to express our meaning, and we recall the meanings of the words we hear. In adding a column of figures, we recall the sums of the numbers. In cooking a meal, we recall the ingredients of the dish we wish to prepare, and the location of the various materials and utensils required for our purpose. In planning a trip, we recall places and routes. Any sort of problem is solved by means of recalled facts put together in a new way. A writer in constructing a story puts together facts that he has previously noted, and any work of the imagination consists of materials recalled from past experience and now built into a new composition.
What Can Be Recalled
If recall is so important in thinking and acting, it is worth while to make a survey of the materials that recall [{367}] furnishes. In general, using the term "recall" rather broadly, we say that any previously learned reaction may be recalled. Writing movements may be said to be recalled when we write, and speech movements when we speak. "Higher units", like the word habits and phrase habits of the telegrapher and typist, are in a broad sense recalled whenever they are used. The typist does not by any means recall the experience of learning a higher unit, but he calls into action again the response that he has learned to make. In the same way, the word habits and phrase habits of vocal speech are called into action, i.e., recalled, whenever we speak.
Besides these motor reactions, tendencies to reaction can be recalled. The attitude of hostility that may have become habitual in us towards a certain person, or towards a certain task, is called into activity at the mention of that person or task. The acquired interest in architecture that we may have formed by reading or travel is revived by the sight of an ambitious group of buildings. A slumbering purpose may be recalled into activity by some relevant stimulus.
Observed facts can be recalled, and this is the typically human form of recall. In animals, we see the recall of tendencies and of learned movements, but no clear evidence of the recall of observed facts. To be recalled with certainty, a fact must have been definitely noted when it was before us. If we have definitely noted the color of a person's eyes, we are in a position to testify that his eyes are brown, for example; otherwise, we may say that we think probably his eyes are brown; because we have certainly noticed that he is dark, and the dark eyes fit best into this total impression.
We say that a fact is recalled when we think of it without its being present to the senses. While the original [{368}] observation of the fact was a response to a sensory stimulus, the recall of it is a response to some other stimulus, some "substitute stimulus". When John is before me, I observe that his eyes are brown in response to a visual stimulus; but I later recall this fact in response simply to the name "John", or in response to the question as to what is the color of John's eyes. I see what a square is by seeing squares and handling them, and later I get this idea simply in response to the word "square" in conversation or reading.