Fig. 53.--(From Ebbinghaus.) The curve of forgetting. The curve sinks at first rapidly, and then slowly, from the 100 per cent line towards the zero line, 100 per cent. here meaning perfect retention, and 0 no retention.
On attempting now to recite it, you make no headway and are inclined to think you have entirely forgotten it. But, finding the list again, yourelearnit, and probably find that your time for relearning is less than the original learning time--unless the lapse of time has run into months. Now consider--if no time at all were needed for relearning, because the list could be recited easily without, your retention would be one hundred per cent. If, on the contrary, it took you just as long now to relearn as it did originally to learn, the retention would be zero. If it takes you now two-thirds as long to relearn as it originally took to learn, then{351}one-third of the work originally done on the list does not have to be done over, andthis saving is the measure of retention.
By the use of this method, the curve of retention, or curve of forgetting, as it is also called, has been determined. It is a curve that first goes down steeply, and then more and more gradually, till it approximates to zero; which means that the loss of what has been learned proceeds rapidly at first and then more and more slowly.
The curve of forgetting can be determined by other methods besides the saving method--by the recall method or by the recognition method; and data obtained by these methods are given in the adjoining tables. It will be seen that the different methods agree in showing a curve that falls off more rapidly at first than later. More is lost in the first hour than in the second hour, and more in the first week than in the second week. Few of the experiments have been continued long enough to bring the curve actually to the zero line, but it has come very close to that line in tests conducted after an interval of two to four months.
PER CENT. OF WORDS RECOGNIZED AT DIFFERENT INTERVALSAFTER BEING SEEN (From Strong)Interval between Per cent. recognized withexposure and test certainty and correctness15 secs. 845 min. 7315 min. 6230 min. 581 hour 562 hours 504 hours 478 hours 4012 hours 381 day 292 days 244 days 197 days 10The subject read a list of 20 disconnected words oncethrough, giving careful attention to each word.Immediately at the close of the reading he performed anexample in mental arithmetic, to prevent his reviewing thelist of words mentally. After an interval, he was shownthese{352}twenty words mixed with twenty others, and hadto pick out those he surely recognized as having beenshown before. Many lists were used, for testing after thedifferent intervals. Five adult subjects took part in theexperiment, and in all 15 lists were used with eachinterval; the per cents. given in the table are theaverages for the 15 lists.THE PER CENT. OF ERROR IN RECALLING DETAILS OF APICTURE AFTER DIFFERENT INTERVALS OF TIME(From Dallenbach)Time of test Per cent, of error Per cent of errorin spontaneous in answeringrecall questions regardingthe pictureImmediatelyafter exposure 10 14After 5 days 14 18After 15 days 18 20After 46 days 22 22The picture was placed in the subject's hands, and heexamined it for one minute, at the end of which time hewrote down as complete a description of the picture aspossible, and then answered a set of sixty questionscovering all the features of the picture. After five dayshe was retested in the same way, and again after fifteendays, etc. In one respect this is not a typical memoryexperiment, since the test after five days would revivethe subject's memory of the picture and slacken theprogress of forgetting. The experiment corresponds moreclosely to the conditions of ordinary life, when we dorecall a scene at intervals; or it corresponds to theconditions surrounding the eye-witness of a crime, whomust testify regarding it, time after time, before police,lawyers and juries. However, the subjects in thisexperiment realized at the time that they were to beexamined later, and studied the picture more carefullythan the eye-witness of a crime would study the eventoccurring before his eyes; so that the per cent. of errorwas smaller here than can be expected in the courtroom.
It must be understood that this classical curve of forgetting only holds good, strictly, for material that hasbarelybeen learned. Reactions that have been drilled in thoroughly and repeatedly fall off very slowly at first, and the further course of the curve of forgetting has not been accurately followed in their case. A typist who had spent perhaps two hundred hours in drill, and then dropped typewriting for a year, recovered the lost ground in less than an hour of fresh practice, so that the retention, as measured by the saving method, was over ninety-nine per cent.
Somewhat different from the matter of the curve of forgetting is the question of therate of forgetting, as{353}dependent on various conditions. The rate of forgetting depends, first, on the thoroughness of the learning, as we have just seen. It depends on the kind of material learned, being very much slower for meaningful than for nonsense material, though both have been learned equally well. Barely learned nonsense material is almost entirely gone by the end of four months, but stanzas of poetry, just barely learned, have shown a perceptible retention after twenty years.
Very fortunately, the principles of economy of memorizing hold good also for retention. Forgetting is slower when relationships and connections have been found in the material than when the learning has been by rote. Forgetting is slower after active recitation than when the more passive, receptive method of study has been employed. Forgetting is slower after spaced than after unspaced study, and slower after whole learning than after part learning.
An old saying has it that quick learning means quick forgetting, and that quick learners are quick forgetters. Experiment does not wholly bear this out. A lesson that is learned quickly because it is clearly understood is better retained than one which is imperfectly understood and therefore slowly learned; and a learner who learns quickly because he is on the alert for significant facts and connections retains better than a learner who is slow from lack of such alertness. The wider awake the learner, the quicker will be his learning and the slower his subsequent forgetting; so that one is often tempted to admonish a certain type of studious but easy-going person, "for goodness' sake not to dawdle over his lessons", with any idea that the more time he spends with them the longer he will remember them. More gas! High pressure gives the biggest results, provided only it is directed into high-level observation, and does not simply generate fear and worry and a rattle-brained frenzy of rote learning.
{354}
Having committed something to memory, how do we get it back when we want it? To judge from such simple cases as the animal's performance of a previously learned reaction, all that is necessary is astimuluspreviously linked with the response. How, for example, shall we get the cat to turn the door-button, this being an act that the cat has previously learned? Why, we put the cat into the same cage, i.e., we supply the stimulus that has previously given the reaction, and trust to it to give the same reaction again. The learning process has attached this reaction to this stimulus. Now can we say the same regarding material committed to memory by the human subject? Is recall a species of learned reaction that needs only the linked stimulus to arouse it?
If you have learned and still retain a list of numbers or syllables, you can recite it on thinking of it, on hearing words that identify it in your mind, or on being given the first few items in the list as a start. The act of reciting the list became linked, during the learning, with the thought of the list, with words signifying this particular list, and with the first items of the list; therefore, these stimuli can now arouse the reaction of reciting the list. As you advance into the list, reciting it, the parts already recited act as stimuli to keep you going forward. In the same way, if you have memorized Hamlet's soliloquy, this title serves as the stimulus to make you recall the beginning of the speech and that in turn calls up the next part and so on; or, if you have analyzed the speech into an outline, the title calls up the outline and the outline acts as the stimulus to call up the several parts that were attached to the outline in the process of memorization. When one idea calls up another, the first acts as a stimulus and the second is a{355}response previously attached to this stimulus. In general, then, recall is a learned response to a stimulus.
There is an exceptional case, where recall seems to occur without any stimulus. This form of recall goes by the name ofperseveration, and a good instance of it is the "running of a tune in the head", shortly after it has been heard. Another instance is the vivid flashing of scenes of the day before the "mind's eye" as one lies in bed before going to sleep. It appears as if the sights or sounds came up of themselves and without any stimulus. Possibly there is some vague stimulus which cannot itself be detected. Only a slight stimulus would be needed, because these recent and vivid experiences are so easily aroused.
Sometimes recall fails to materialize when we wish it and have good reason for expecting it. We know this person's name, as is proved by the fact that we later recall it, but at the moment we cannot bring it up. We know the answer to this examination question, but in the heat of the examination we give the wrong answer, though afterwards the right answer comes to mind. This seldom happens with thoroughly learned facts, but frequently with facts that are moderately well known. Some sort of inhibition or interference blocks recall.
One type of interference is emotional. Fear may paralyze recall. Anxious self-consciousness, or stage fright, has prevented the recall of many a well-learned speech, and interfered with the skilful performance of many a well-trained act.
Distraction is an interference, since it keeps the stimulus from exerting its full effect. Sometimes the stimulus that is present has been linked with two or more responses, and these get in each other's way; as you will sometimes hear a speaker hesitate and become confused from having two ways{356}of expressing the same thought occur to him at almost the same instant.
There are no sure rules for avoiding these intricate interferences; and, in general, recall being a much less manageable process than memorizing, we do not have anything like the same mass of practical information regarding it. One or two suggestions have some value, however.
(1) Give the stimulus a good chance. Look squarely at the person whose name you wish to recall, avoiding doubt as to your ability to recall it; for doubt is itself a distraction. Put yourself back into the time when you formerly used this person's name. In extemporaneous speaking, go ahead confidently, avoid worry and self-consciousness, and, full of your subject, trust to your ideas to recall the words as needed. Once carried away with his subject, a speaker may surprise himself by his own fluency.
(2) Drop the matter for a while, and come back to it afresh. Sometimes, when you cannot at once recall a name, it does no good to keep doggedly hunting, while half an hour later you get it without the least trouble. The explanation of this curious phenomenon is found in interference and the dying out of interference. At your first attempt to recall the name, you simply got on the wrong track, and thus gave this wrong track the "recency" advantage over the right track; but this temporary advantage fades out rapidly with rest and leaves the advantage with the track most used in the past.
The rule to drop a matter when baffled and confused, and take it up again when fresh, can be used in more complex cases than hunting for a name. When, in trying to solve any sort of problem, you find yourself in a rut, about the only escape is to back off, rest up, and make an entirely fresh start.
{357}
The fourth question propounded at the beginning of the chapter, as to how we can know that the fact now recalled is what we formerly committed to memory and now wish to recall, is part of the larger question of how we recognize. What we recognize includes not only facts recalled, but also facts not recalled but presented a second time to the senses. Recognition of objects seen, heard, touched, etc., is the most rudimentary form of memory. The baby shows signs of recognizing persons and things before he shows signs of recall. A little later, he recognizes and understands words before he begins to speak (recall) them; and everybody's vocabulary of recognized words remains much greater than his speaking vocabulary. We recognize faces that we could not recall, and names that we could not recall. In short, recognition is easier than recall.
Consequently any theory of recognition that makes it depend on recall can scarcely be correct. One such theory held that an object is recognized by recalling its original setting in past experience; an odor would be recognized by virtue of recalling the circumstances under which it was formerly experienced. Now sometimes it does happen that an odor which seems familiar, but cannot be identified, calls up a past experience and thus is fully recognized; but such "indirect recognition" is not the usual thing, for direct recognition commonly takes place before recall of the past experience has time to occur. You see a person, and know him at once, though it may require some moments before you can recall where and when you have seen him before.
Recognition may be more or less complete. At its minimum, it is simply a "feeling of familiarity" with the object; at its maximum it is locating the object precisely in your autobiography. You see a man, and say, "He looks{358}familiar, I must have seen him somewhere", and then it dawns on you, "Oh! yes, now I know exactly who he is; he is the man who . . ." Between these extremes lie various degrees of recognition. This man seems to be some one seen recently, or a long, long time ago, or at the seashore, or as a salesman in a store; or as some one you looked up to, or felt hostility towards, or were amused at; and often these impressions turn out to be correct, when you succeed in fully recognizing the person. These impressions resemble the first signs of recognition in the baby's behavior; you say that the baby remembers people because he smiles at one who has pleased him before, and shrinks from one who has displeased him.
Recognition is a form of learned response, depending on previous reaction to the object recognized. To recognize an object is to respond to it as we responded before--except for the feeling of familiarity, which could not occur the first time we saw the object. But notice this: though the object is the same identical object it was before, it may have changed somewhat. At least, its setting is different; this is a different time and perhaps a different place, and the circumstances are bound to be more or less different. In spite of this difference in the situation, we make the same response as before.
Now, the response we made to the object in its original setting was a response to the whole situation, objectplussetting; our response to the object was colored by its setting. When we now recognize the object, we make the same response to the object in a different setting; the response originally called out by the objectplusits setting is now aroused by the object alone. Consequently we have an uneasy feeling of responding to a situation that is not present.{359}This uneasy feeling is the feeling of familiarity in its more haunting and "intriguing" form.
We see some one who seems familiar and who arouses a hostile attitude in us that is not accounted for in the least by his present actions. We have this uneasy feeling of responding to a situation that is not present, and cannot rest till we have identified the person and justified our hostile attitude.
Or, we see some one who makes us feel as if we had had dealings with him before in a store or postoffice where he must have served us; we find ourselves taking the attitude towards him that is appropriate towards such a functionary, though there is nothing in his present setting to arouse such an attitude. Or, we see some one in the city streets who seems to put us back into the atmosphere of a vacation at the seashore, and by searching our memory we finally locate him as an individual we saw at such and such a resort. At other times, the feeling of familiarity is rather colorless, because the original situation in which the person was encountered was colorless; but we still have the feeling of responding to something that is not present. We make, or start to make, the same response to the person that we originally made to himplushis setting, and this response to something that is not there gives the feeling of familiarity.
When we see the same person time after time in the same setting, as when we go into the same store every morning and buy a paper from the same man, we cease to have any strong feeling of familiarity at sight of him, the reason being that we are always responding to him in the same setting, and consequently have no feeling of responding to something that is not there. But if we see this same individual in a totally different place, he may give us a queer feeling of familiarity. When we see the same person time after time{360}in various settings, we end by separating him from his surroundings and responding to him alone, and therefore the familiarity feeling disappears.
Complete recognition, or "placing" the object, involves something more than these feelings and rudimentary reactions. It involves the recall of a context or scheme of events, and a fitting of the object into the scheme.
The important question whether memory can be improved by any form of training breaks up, in the light of our previous analysis, into the four questions, whether memorizing can be improved, whether the power of retention can be improved, whether recall can be improved, and whether recognition can be improved. As to recognition, it is difficult to imagine how to train it; the process is so elusive and so direct. It has been found, however, that practice in recognizing a certain class of objects improves one's standards of judgment as to whether a feeling of familiarity is reliable or not; it enables one to distinguish between feelings that have given correct recognitions and the vaguer feelings that often lead one astray.
As to recall, certain hints were given above as to the efficient management of this process, and probably practice in recalling a certain sort of facts, checked up by results, would lead to improvement.
As to retention, since this is not a performance but a resting state, how could we possibly go about to effect an improvement? One individual's brain is, to be sure, more retentive than another's; but that seems a native trait, not to be altered by training.
On the other hand, the process of committing to memory, being a straightforward and controllable activity, is{361}exceedingly susceptible to training, and it is there, for the most part, that memory training should be concentrated in order to yield results. It does yield marked results. In the laboratory, the beginner in learning lists of nonsense syllables makes poor work of it. He is emotionally wrought up and uncertain of himself, goes to work in a random way (like any beginner), perhaps tries to learn by pure rote or else attempts to use devices that are ill-adapted to the material, and has a slow and tedious job of it. With practice in learning this sort of material, he learns to observe suitable groupings and relationships, becomes sure of himself and free from the distraction of emotional disturbance, and may even come to enjoy the work. Certainly he improves greatly in speed of memorizing nonsense syllables. If, instead, he practises on Spenser's "Faery Queen", he improves in that, and may cut down his time for memorizing a twelve-line stanza from fifteen minutes to five. This improvement is due to the subject's finding out ways of tackling this particular sort of material. He gets used to Spenser's style and range of ideas. And so it is with any kind of material; practice in memorizing it brings great improvement in memorizing that particular material.
Whether practice with one sort of material brings skill that can be "transferred", or carried over to a second kind of material, is quite another question. Usually the amount oftransferis small compared with the improvement gained in handling the first material, or compared with the improvement that will result from specific training with the second kind. What skill is transferred consists partly of the habit of looking for groupings and relationships, and partly in the confidence in one's own ability as a memorizer. It is really worth while taking part in a memory experiment, just to know what you can accomplish after a little training. Most persons who complain of poor memory would be{362}convinced by such an experiment that their memory was fundamentally sound. But these laboratory exercises do not pretend to develop any general "power of memory", and the much advertised systems of memory training are no more justified in such a claim. What is developed, in both cases, is skill in memorizing certain kinds of material so as to pass certain forms of memory test.
One who suffers from poor memory for any special material, as names, errands, or engagements, probably is not going to work right in committing the facts to memory; and if he gives special attention to this particular matter, keeping tab on himself to see whether he improves, he is likely to find better ways of fixing the facts and to make great improvement. It was said of a certain college president of the older day that he never failed to call a student or alumnus by name, after he had once met the man. How did he do it? He had the custom of calling each man in the freshman class into his office for a private interview, during which, besides fatherly advice, he asked the man personal questions and studied him intently. He was interested in the man, he formed a clear impression of his personality, and to that personality he carefully attached the name. Undoubtedly this able scholar was possessed of an unusually retentive memory; but his memory for names depended largely on his method of committing them to memory.
Contrast this with the casual procedure of most of us on being introduced to a person. Perhaps we scarcely notice the name, and make no effort to attach the name to the personality. To have a good memory for names, one needs to give attention and practice to this specific matter. It is the same with memory for errands; it can be specifically trained. Perhaps the best general hint here is to connect the errand beforehand in your mind with the{363}place where you should think, during the day, to do the errand.
Often some littlemnemonic systemwill help in remembering disconnected facts, but such devices have only a limited field of application and do not in the least improve the general power of memory. Some speakers, in planning out a speech, locate each successive "point" in a corner of the hall, or in a room of their own house; and when they have finished one point, look into the next corner, or think of the next room, and find the following point there. It would seem that a well-ordered discourse should supply its own logical cues so that such artificial aids would be unnecessary.
In training the memory for the significant facts that constitute the individual's knowledge of his business in life, the best rule is to systematize and interrelate the facts into a coherent whole. Thus, a bigger and stronger stimulus is provided for the recall of any item. This, along with the principles of "economy" in memorizing, is the best suggestion that psychology has to make towards memory improvement.
{364}
1. In outlining the chapter, regroup the material so as to separate the practical applications from the description of memory processes. This gives you two main heads: A. Memory processes, and B. The training and management of memory. Each of these main heads should be divided into four sub-heads: Memorizing, retention, etc., and the information contained in the chapter grouped under these sub-heads.2. Disorders of memory can be classified under the four heads of disorders of learning, of retention, of recall and of recognition. Where would you place each of the following?
(a) Aphasia, where, through brain injury, the subject's vocabulary is very much reduced.(b) The condition of the very old person, who cannot remember what has happened during the day, though he still remembers experiences of his youth.(c) The "feeling of having been there before", in which you have a weird impression that what is happening now has happened in just the same way before, as if events were simply repeating themselves.(d) The loss of memory which sometimes occurs after a physical or emotional shock, or after a fever, and which passes away after a time.
3. How fully can you recall what happened on some interesting occasion when you were a child of 5-8 years? Dwell on the experience, and see whether you get back more than at first seemed possible. Try the same with an experience of five years ago.4. If a student came to you for advice, complaining of poor memory, and said that though he put hours and hours on a lesson and read it over many times, still he failed on it, what questions would you ask regarding his method of study, and what suggestions would you offer?5. An experiment on memorising lists of numbers. Prepare several lists of 20 digits, and shuffle them; draw out one and take your time for learning it to the point of perfect recitation. Write an introspective account of the process. Repeat with a second list6. An experiment in memorizing word-pairs. Prepare 20 pairs of words as follows: take 20 cards or slips of paper, and write a different word on each. Then turn them over, shuffle, and write another word on the back of each. Thus, though you may know what words you have written, you do not how how they are paired; and now your job is to learn the pairs. Note starting time, take the first card and look at both{365}sides, and study the pair of words on this card for about 5 seconds, passing then to the second card, and so on through the pack. Shuffle the pack, take the top card and give yourself about 5 seconds to recall the word on the reverse, then turning the card over and reading it. Proceed in this way through the pack, shuffle again, and repeat. Continue thus till you score 100 per cent. Note total time required, and report on process of memorizing.7. Memorizing a series of related words. Prepare a list of 40 words, as follows: first write the numbers 1 to 40 in a column; then write any word for No. 1; for No. 2, write some word closely related to No. 1; for No. 3 some word closely related to No. 2; and so on. Your list, for example, might begin like this: house, roof, chimney, soot, fire, coal, mine, miner, strike, arbitration, etc. Having finished writing your list, cover it and see how much of it you can recite without further study, and how long it takes you to complete the memorizing. Explain the results obtained.8. Plot the curve of forgetting from the following data, which give the per cent, of retention of stanzas of a poem at different intervals after the end of memorizing.
after 1 day 79%after 2 days 67%after 6 days 42%after 14 days 30%after 30 days 24%
Ebbinghaus,On Memory, 1885, translated by Ruger and Bussenius, 1918. This is the pioneer experimental study of memory, and is still worth reading, and is not specially hard reading.
James's chapter on Memory, in Vol. I of hisPrinciples of Psychology, 1890, is still one of the best references, and contains some important remarks on the improvement of memory.
Of the numerous special studies on memory, mention may be made of that by Arthur I. Gates,Recitation as a Factor in Memorizing, 1917, which, on pp. 65-104, gives a valuable account of the various devices used by one who is memorizing.
For the psychology of testimony, see G. M. Whipple's article on "The Obtaining of Information: Psychology of Observation and Report", in thePsychological Bulletinfor 1918, Vol. 15, pp. 217-248, especially pp. 233-248. See also a popularly written account of the matter by Münsterberg, inOn the Witness Stand, 1908, pp. 15-69.
{366}
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.
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. Writingmovementsmay 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,tendenciesto 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.
Observedfactscan 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.
Now, cansensationsbe recalled, can they be aroused except by their natural sensory stimuli? Can you recall the color blue, or the sound of a bugle, or the odor of camphor, or the feel of a lump of ice held in the hand? Almost every one will reply "Yes" to some at least of these questions. One may have a vivid picture of a scene before the "mind's eye", and another a realistic sound in the "mind's ear", and they may report that the recalled experience seems essentially the same as the original sensation. Therefore, sensory reactions are no exception to the rule of recall by a substitute stimulus.
A sensation or complex of sensations recalled by a substitute stimulus is called a "mental image" or a "memory image".
Individuals seem to differ in the vividness or realism of their memory images--the likeness of the image to an actual sensation--more than in any other respect. Galton, in taking a sort of census of mental imagery, asked many persons to call up the appearance of their breakfast table as they had sat down to it that morning, and to observe how lifelike the image was, how complete, how adequate in respect to color, how steady and lasting, and to compare{369}the image in these respects with the sensory experience aroused by the actual presence of the scene. Some individuals reported that the image was "in all respects the same as an original sensation", while others denied that they got anything at all in the way of recalled sensation, though they could perfectly well recall definite facts that they had observed regarding the breakfast table. The majority of people gave testimony intermediate between these extremes.
Individuals differ so much in this respect that they scarcely credit each other's testimony. Some who had practically zero imagery held that the "picture before the mind's eye" spoken of by the poets was a myth or mere figure of speech; while those who were accustomed to vivid images could not understand what the others could possibly mean by "remembering facts about the breakfast table without having any image of it", and were strongly tempted to accuse them of poor introspection, if not worse. It is true that in attempting to study images, we have to depend altogether on introspection, since no one can objectively observe another person's memory image, and therefore we are exposed to all the unreliability of the unchecked introspective method. But at the same time, when you cross-question an individual whose testimony regarding his imagery is very different from yours, you find him so consistent in his testimony and so sure he is right, that you are forced to conclude to a very real difference between him and yourself. You are forced to conclude that the power of recalling sensations varies from something like one hundred per cent, down to practically zero.
Individuals may also differ in thekindof sensation that they can vividly recall. Some who are poor at recalling visual sensations do have vivid auditory images, and others who have little of either visual or auditory imagery call up{370}kinesthetic sensations without difficulty. When this was first discovered, a very pretty theory of "imagery types" was built upon it. Any individual, so it was held, belonged to one or another type: either he was a "visualist", thinking of everything as it appears to the eyes, or he was an "audile", thinking of everything according to its sound, or he was a "motor type", dealing wholly in kinesthetic imagery, or he might, in rare cases, belong to the olfactory or gustatory or tactile type.
Fig. 54.--Individual differences in mental imagery. According to the type theory, every individual has a place in one or another of the distinct groups, visual, auditory, tactile, kinesthetic, or olfactory. According to the facts, the majority, of individuals cluster in the middle space, and form a single large group, though some few are extremely visual, or auditory, etc., in their imagery. (Figure text: according to the type theory, according to the facts)
But the progress of investigation showed, first, that a "mixed type" must also be admitted, to provide for individuals who easily called up images of two or more different senses; and, later on, that the mixed type was the most common. In fact, it is now known to be very unusual for an individual to be confined to images of a single sense. Nearly every one gets visual images more easily and frequently than those of any other sense, but nearly every one has, from time to time, auditory, kinesthetic, tactile and olfactory images. So that the "mixed type" is the only real type, the extreme visualist or audile, etc., being exceptional and not typical.
{371}
Recalled sensations are commonly inferior to their originals, both in the enjoyment they afford and in the use that can be made of them. They are likely to be inferior in several respects.
(1) An image has usually less color, or tone--less body, realism and full sensory quality--than a sensation aroused by its appropriate peripheral stimulus. While you may be able to call up a fairly good image of your absent friend's face, the actual presence of your friend would be more satisfactory, just as a sensory experience. You may be able to run over a piece of music "in your head", and if your auditory imagery is strong you may even run over an orchestral piece, and get the tone quality of the various instruments; but, after all, such a mental concert is an imperfect substitute for a real orchestra. You enjoy a real whiff of the sea more than the best olfactory image you can summon. There is something lacking in these recalled sensations, and the trouble seems to be that they are not sensations enough; they lack sensory body.
(2) Images are apt to be sketchy and lacking in detail, and also narrow and lacking in background.
(3) Images are apt to be unsteady and fleeting, as compared with actual sensations. Where the peripheral stimulus, continuing, keeps the sensation going, the substitute stimulus that recalls a sensation is not so effective in this respect, any more than in giving body and detail. In all these respects, an image is less enjoyable and satisfying than an actual sensation.
(4) On the more practical side, images are inferior to the actual presence of an object, in that we cannot utilize the image as a source of new information.{372}Wecannot observe factsin the image of a thing that we have not observed in the actual presence of the thing.
At one of the universities, there is a beautiful library building, with a row of fine pillars across the front, and the students pass this building every day and enjoy looking at it. It has long been a favorite experiment in the psychology classes at that university to have the students call up an image of the library, and to have them state how clear their image is, how complete and how vivid. Then they are asked to count the pillars from their image, and to tell what kind of capitals the pillars have, and whether the shafts are plain or fluted. But at this point the students begin to object. "We have never counted those pillars, and cannot be expected to know the number now." In fact, few of them give the correct number, and those who have reported clear and vivid images are little better off in this respect than those whose images are dim and vague.
The image, then, does not give you facts that you did not observe in the presence of the object. The substitute stimulus, which now recalls the image, only recalls responses which you made when the real object was the stimulus. If you looked at the object simply to get its general appearance, the general appearance is all you can recall. If you noted the color of the object, you can probably recall the color. If you noted such details as the number of pillars, you can recall these details. But the substitute stimulus that now arouses the image is by no means the equivalent of the original peripheral stimulus in making possible a variety of new reactions. Its only linkage is with reactions actually made by you in response to the real object. The substitute stimulus, such as the name of a building, became linked with responses actually made by you, not with responses that you simply might have made, when the object was present. This important fact is closely related to the{373}unreliability of testimony that was mentioned before under the head of "unintentional memory". [Footnote:See pp. 346-348.] Facts recalled are facts previously observed.
It is true, of course, that recalled facts can be compared and new facts be observed by the comparison. We may recall how John looks, and how James looks, and note the fact, not previously observed, that they look alike. A great deal can be inferred in this way by a person who is sitting in his room far from the objects thought about. But this noting of the relationships of different objects is a very different matter from observing what is there, in a single object or scene. What is there can only be observed when you are there.
Many observed facts are not strictly facts of sensation, though observed by means of the senses. Let us suppose, for an example, that your attention is caught by the bright green new leaves at the tips of the branches of an evergreen tree in summer, and that you notice also the darker green of the older leaves further back along the branches, and, exploring deeper, find leaves that are dead and brown, while still further in they have all fallen off, leaving bare branches reaching back to the trunk; so that you finally "see" how the tree is constructed, as a hollow cone of foliage supported by an interior framework of branches. All this has meant a lot of different reactions on your part, and the final "seeing" of how the tree is constructed would scarcely be called a sensation, since it has required mental work beyond that of simply seeing the tree. It is a response additional to the strictly sensory response of seeing the tree.
Now the question is whether this additional response can be recalled, without recalling at the same time the primary{374}response of seeing the tree. Can we recall the fact observed about the tree without at the same time seeing the tree "in the mind's eye"? Must we necessarily have an image of the tree when we recall the way the tree is constructed?
Since getting the general sensory appearance of the tree, and observing the way it is constructed, are two different responses, it seems quite conceivable that either fact should be recalled without the other; and no one doubts that the sensory appearance of the tree can be recalled without the other observed fact coming up along with it. But many authorities have held that the non-sensory fact could not be recalled alone; in other words, they have held that every recalled fact comes as a sensory image, or with a sensory image. Persons with ready visual imagery are of course likely to get a visual image with any fact they may recall. But persons whose visual imagery is hard to arouse say that they recall facts without any visual image. I who write these words, being such a person, testify that while I have been writing and thinking about that tree I have not seen it before my mind's eye.
It is true, however, that I have had images during this time--auditory images of words expressing the facts mentioned. Another individual might have had kinesthetic images instead of either visual or auditory. But can there be a recall of fact withoutanysensory image?
On this question, which has been called the question of "imageless thought", though it might better be called that of "imageless recall", controversy has raged and is not yet at rest, so that a generally accepted conclusion cannot be stated. But the best indications are to the effect, first, that vague and fleeting images, especially of the kinesthetic sort, are often present without being detected except by very fine introspection, some image being pretty sure to come up every few seconds when we are engaged in silent thought or{375}recall; but, second, that images are not present every second of the time, and that at the instant when a non-sensory fact is recalled it is apt to be alone.
Since a vivid mental image may be "in all respects the same as an actual sensation", according to the testimony of some people, the question arises how, then, an image is distinguished from a sensation. Well, the image does not usually fit into the objective situation present to the senses. But if it does fit, or if the objective situation is lost track of, then, as a matter of fact, the image may be taken for a sensation.
You see some beautiful roses in the florist's window, and yousmellthem; the odor fits into the objective situation very well, till you notice that the shop door is shut and the window glass impervious to odors, from which you conclude that the odor must have been your image.
You are lost in thought of an absent person, till, forgetting where you are, you seem to see him entering the door; he "fits" well enough for an instant, but then the present situation forces itself upon you and the image takes its proper place.
You are half asleep, almost lost to the world, and some scene comes before you so vividly as to seem real till its oddity wakens you to the reality of your bedroom. Or you are fully asleep, and then the images that come are dreams and seem entirely real, since contact with the objective situation has been broken.
Images taken for real things are common in some forms of mental disorder. Here the subject's hold on objective fact is weakened by his absorption in his own desires and fears, and he hears reviling voices and smells suspicious{376}odors or sees visions that are in line with his desires and fears.
Such false sensations are called "hallucinations". An hallucination is an image taken for a sensation, a recalled fact taken for a present objective fact. It is a sensory response, aroused by a substitute stimulus, without the subject's noticing that it is thus aroused instead of by its regular peripheral stimulus.
Quite a large number of people are so constituted as to hear sounds as if colored, a deep tone perhaps seeming dark blue, the sound of a trumpet a vivid red, etc. Each vowel and even each consonant may have its own special color, which combine to give a complex color scheme for a word. Numbers also may be colored. This colored hearing is the commonest form of "synesthesia", which consists in responding to a stimulus acting on one sense, by sensations belonging to a different sense. Whether the persons so constituted as to respond in this way are constituted thus by nature or by experience is uncertain, though the best guess is that the extra sensations are images that have become firmly attached to their substitute stimuli during early childhood.
Mental processes that depend on recall are called "associative processes", since they make use of associations or linkages previously formed. When some definite interest or purpose steers the associative processes, we speak of "controlled association", contrasting this with the "free association" that occurs in an idle mood, when one thought simply calls up another with no object in view and no more than fleeting desires to give direction to the sequence of thoughts.
Reveryaffords the best example of free association. I{377}see my neighbor's dog out of my window, and am reminded of one time when I took charge of that dog while my neighbor was away, and then of my neighbor's coming back and taking the dog from the cellar where I had shut him up; next of my neighbor's advice with respect to an automobile collision in which I was concerned; next of the stranger with whom I had collided, and of the stranger's business address on the card which he gave me; next comes a query as to this stranger's line of business and whether he was well-to-do; and from there my thoughts switch naturally to the high cost of living.
This is rather a drab, middle-aged type of revery, and youth might show more life and color; but the linkages between one thought and the next are typical of any revery. The linkages belong in the category of "facts previously observed". I had previously observed the ownership of this dog by my neighbor, and this observation linked the dog and the neighbor and enabled the dog to recall the neighbor to my mind. Most of the linkages in this revery are quite concrete, but some are rather abstract, such as the connection between being well-to-do (or not) and the high cost of living; but, concrete or abstract, they are connections previously observed by the subject. Sometimes the linkage keeps the thoughts within the sphere of the same original experience, and sometimes switches them from one past experience to another, or even away from any specific past experience to general considerations; yet always the linkage has this character, that the item that now acts as stimulus has been formerly combined in observation with the other item that now follows as the response. One fact recalls another when the two have been previously observed as belonging together.
But suppose, as is commonly the case, that the fact now present in my mind has been linked, in different past{378}experiences, with several different facts. Then two questions demand our attention: whether all these facts are recalled; and, if not, what gives the advantage to the fact actually recalled over the others that are not recalled.
The answer to the first question is plain. The fact first present in mind does not call up all the associated facts, but usually only one of them, or at least only one at a time. My neighbor, in the example given, though previously associated with a dozen other facts, now calls up but two of these facts, and those two not simultaneously but one after the other. We see a law here that is very similar to a law stated under the head of attention. There, we said that of all the objects before us that might be noticed only one was noticed at a time; and here we say that of all the objects that might be recalled to mind by association only one is recalled at a time. Both statements can be combined into the one general "law of reaction" which was mentioned before, that of all the responses linked to a given stimulus (or complex of stimuli) only one is actually aroused at the same instant, though several may be aroused in succession, provided the stimulus continues.
In revery, the stimulus usually does not continue. The first fact thought of gives way to the fact that it recalls, and that to one that it recalls in turn, and so on, without much dwelling on any fact. But if we do dwell on any fact--as upon the thought of a certain person--then this stimulus, continuing to act, calls up in succession quite a number of associated facts.
If, then, only one of the several facts associated with the stimulus is recalled at once, our second question presents itself, as to what are the factors of advantage that cause one rather than another of the possible responses to occur. The fact first in mind might have called up any one of several facts, having been linked with each of them in past{379}experience; and we want to know why it recalls one of these facts rather than the rest.
The factors of advantage in recall are the factors that determine the strength of linkage between two facts; and they are:
thefrequencywith which the linkage has occurred;therecencywith which it has occurred; andtheintensitywith which it has occurred.
If I have frequently observed the connection of two facts, the linkage between them is strong; if I have recently observed their connection, the linkage between them is strong till the "recency value" dies away; and if my observation of the connection of the two facts was a vivid experience, or intense reaction, then, also, the linkage between them is strong. If these three factors of advantage work together in favor of the same response, then that response is sure to occur; but if the three factors pull different ways, we should have to figure out the balance of advantage before we could predict which of the possible responses would actually be made. Naturally enough, even the skilful psychologist is often unable to strike the balance between the three factors. He does know, however, and all of us know in a practical way, that strong recency value offsets a lot of frequency; so that a mere vague allusion to a very recent topic of conversation can be depended on to recall the right facts to the hearer's mind, even though they lie outside of his habitual line of interest. "James", by virtue of frequency, means your brother or friend; but after the lecturer has been talking about the psychologist James, repetition of this name infallibly recalls the psychologist to mind.
Besides frequency, recency and intensity, there is, indeed, another factor to be taken into account; and that is the{380}present state of the subject's mind. If he is unhappy, unpleasant associations have the advantage; if happy, pleasant. If he is absorbed in a given matter, facts related to that matter have the advantage. Frequency, recency and intensity summarize thehistoryof associations, and measure their strength as dependent on their history; but the present state of mind is an additional directive factor, and when it has much to do with recall, we speak of directed or controlled association.
Before we pass to the topic of controlled association, however, there is another form of free association, quite different from revery, to be examined. There is an experiment, called thefree association test, in which the subject is given a series of words as stimuli, and is asked to respond to each word by speaking some other word, the first that is recalled by the stimulus. No special kind of word need be given in response, but simply thefirst word recalled. Though this is called free association, it is controlled to the extent that the response must be a word, and the result is very different from revery. Instead of the recall of concrete facts from past experience, there is recall of words. If you give the subject the stimulus word, "table", his response is "chair" or "dinner", etc., and often he does not think of any particular table, but simply of the word. Words are so often linked one with another that it is no wonder that one recalls another automatically. What particular word shall be recalled depends on the frequency, recency and intensity of past linkage.
Though this form of test seems so simple as almost to be silly, it is of use in several ways. When a large number of stimulus words are used, and the responses classified, some persons are found to favor linkages that have a personal significance--"egocentric responses", these are called--while other persons run to connections that are{381}impersonal and objective. Thus the test throws some light on the individual'shabitsof attention. The test has also a "detective" use, based upon the great efficacy of the factor ofrecency; you may be able by it to tell whether an individual has recently had a certain matter in mind. If he happens to be an individual who has recently committed some crime, properly selected stimulus words will lead him to recall the scene of the crime, and thus to make responses that betray him, unless he checks them and so arouses suspicion by his hesitation. Another use of the test is for unearthing a person's emotional "complexes", which of course possess a highintensityvalue. If the subject shows hesitation and embarrassment in responding to words referring to money, the indication is that he is emotionally disturbed over the state of his finances. One person who consulted a doctor for nervousness made peculiar responses to stimulus words relating to the family, and was discovered to be much disturbed over his family's opposition to his projected marriage. The free association test is useful rather as giving the experienced psychologist hints to be followed up than as furnishing sure proof of the contents of the subject's mind.
There is a controlled association test conducted like this one in free association, except that the subject is required to respond to each stimulus word by a word standing in a specified relation to it. To one series of words he must respond by saying their opposites; to another, by mentioning a part of each object named; to another series, consisting of names of countries, he must respond by naming as quickly as possible the capital of each country named; and there are many tests of this sort, each dealing with some class of relationships which, being often observed, are easily handled{382}by a person of normal intelligence. The intelligent subject makes few errors in such a test, and responds in very quick time. Indeed, the remarkable fact is that he takes less time to respond in an easy controlled association test than in the free association test; which shows that the "control" acts not simply to limit the response, but also tofacilitateit.
The "control" here is often called by the name of "mental set". It is a good example of a "reaction tendency". On being told you are to give opposites, you somehow set or adjust your mental machinery for making this type of response. The mental set thus thrown into action facilitates responses of the required type, while inhibiting other responses that would readily occur in the absence of any directive tendency. If the word "good" came as a stimulus word in a free association test, it might easily arouse the responses, "good day", "good night", "good boy", "good better", and many besides, since all of these combinations have been frequently used in the past; and the balance of frequency, recency and intensity might favor any one of these responses. But when the subject is set for opposites, the balance of these factors has little force as against the mental set. The mental set for opposites favors the revival of such combinations as "new--old", "good--bad", and such others of this class as have been noted and used in the subject's past experience.
Mental set is a selective factor, a factor of advantage. It does not supersede the previously formed associations, or work independently of them, but selects from among them the one which fits the present task. Does it get in its work after recall has done its part, or before? Does it wait till recall has brought up a number of responses, and then pick out the one that fills the bill? No, it often works much too quickly for that, giving the right response instantly; and introspection is often perfectly clear that none but the right{383}response is recalled at all. The selective influence of the mental set is exertedbefore recall; it facilitates the right recall and inhibits recall of any but the right response.
In controlled association, as in free association, only one of the facts previously linked with the stimulus is recalled at a time; but while in free association the factors of frequency, recency and intensity of past linkage determine which of the many possible facts shall be recalled, in controlled association the additional factor of mental set is present and has a controlling influence in determining which fact shall be recalled. Thus, in an opposites test, the stimulus word "good" promptly calls up the pair "good--bad", because the mental set for opposites gives this response a great advantage over "good night" and other responses which may have a very strong linkage with the stimulus word.
The mental set is itself a response to a stimulus. It is an inner response thrown into activity by some stimulus, such as the stimulus of being asked to give the opposites of a series of words that are presently to be shown or spoken. This inner response of getting ready for the task can be introspectively observed by a person who is new to this type of test. It may take the form of mentally running over examples of opposites--or whatever kind of responses are to be called for--or it may take the form of calling up some image or diagram or gesture that symbolizes the task. A visual image of the nose on the face may serve as a symbol of the part-whole relationship, a small circle inside a larger one may symbolize the relation of an object to a class of objects, and gesturing first to the right and then to the left may symbolize the relationship of opposites. But as the subject grows accustomed to a given task, these conscious symbols fade away, and nothing remains except a general "feeling of readiness" or of "knowing what you are{384}about". The mental set remains in force, however, and is no less efficient for becoming almost unconscious.
Dwelling so long on the test for controlled association may have created the impression that this is a rather artificial and unusual type of mental performance; but in reality controlled association is a very representative mental process, and enters very largely into all forms of mental work. This is true in arithmetical work, for example. A pair of numbers, such as 8 and 3, has been linked in past experience with several responses; it means 83, it means 11, it means 5, and it means 24. But if you are adding, it means 11, and no other response occurs; if you are multiplying, it means 24, and only that response occurs. The mental set for multiplying facilitates the responses of the multiplication table and inhibits those of the addition table, while the mental set for adding does the reverse. Rapid adding or multiplying would be impossible without an efficient mental set. Thus in arithmetic, as in the tests, the mental set is an inner response to thetask.
In reading, there is a mental set which is an inner response to thecontext, and which determines which of the several well-known meanings of a word shall actually be called to mind when the word is read. Presented alone, a word may call up any of its meanings, according to frequency, etc.; but in context it usually brings to mind just the one meaning that fits the context. The same is true of conversation.
The objectivesituationarouses a mental set that controls both thought and action. The situation of being in church, for example, determines the meanings that are got from the words heard, and controls the motor behavior to{385}fit the occasion. The subject, observing the situation, adjusts himself to it, perhaps without any conscious effort, and his adjustment facilitates appropriate mental and motor reactions, while inhibiting others.
Aproblemarouses a mental set directed towards solution of the problem. A difficult problem, however, differs from a context or familiar task or situation in this important respect, that the appropriate response has not been previously linked with the present stimulus, so that, in spite of ever so good a mental set, the right response cannot immediately be recalled. One mustsearchfor the right response. Still, the mental set is useful here, in directing the search, and keeping it from degenerating into an aimless running hither and thither. Problem solution is so different a process from smooth-running controlled association that it deserves separate treatment, which will be given it a few chapters further on, under the caption of reasoning.