Memory And Its Improvement
( Originally Published 1921 )
WE have been speaking of certain special and unusual cases of recall of past experience. They are significant for the psychology of memory, but for the affairs of every-day life the practical question is, How may one's own memory be made efficient? In answering this question we should constantly bear in mind that an efficient memory is selective. It does not reproduce past experiences impartially. Certain facts which we. have observed, heard, or read are important for the matter in hand, and other things, how-ever much they may bear on other questions, have no present significance. If one will notice the arguments and statements of others, one cannot fail to observe the devious mental wanderings from the point. George Meredith gives a good illustration in Evan Harrington. Evan, when horse-back riding, discovered Polly Wheedle shivering under a bush in the rain:
"Bellowing against the thunder, Evan bade her throw back her garment and stand and give him her arms, that he might lift her on the horse behind him.
"There came a muffled answer, on a big sob, as it seemed. And as if heaven paused to hear, the storm was mute.
"Could he have heard correctly? The words he fancied he had heard sobbed were:
"Evan stooped his shoulder, seized the soaked garment, and pulled it back, revealing the features of Polly Wheedle.
"`Oh, Mr. Harrington; oh, ain't I punished!' she whimpered.
"`And what have you been doing to be punished? What brought you here?' said Evan.
"`Somebody drove me to Fallowfield to see my poor sister Susan,' returned Polly, half crying.
"`Well, did he bring you here and leave you?'
"`No; he wasn't true to his appointment the moment I wanted to go back; and I, to pay him off, I determined I'd walk it where he shouldn't overtake me, and on came the storm. . . . And my gown spoilt and such a bonnet!'
"`Who was the somebody?'
"'He's a Mr. Nicholas Frim, sir.'
"`Mr. Nicholas Frim will be very unhappy, I should think.'
"`Yes, that's one comfort,' said Polly ruefully, drying her eyes. . . .
"`You look very pretty.' . . .
"`I can see myself a fright, like my Miss Rose did, making a face in the looking-glass when I was undressing her last night.'
My Miss Rose—what was I going to tell? Oh !—my Miss Rose. You must know, Mr. Harrington, she's very fond of managing; I can see that, though I haven't known her long before she gave up short frocks; and she said to Mr. Laxley, who's going to marry her some day, "She didn't like my lady, the Countess, taking Mr. Harry to herself like that." I can't abear to speak his name, but I suppose he's not a bit more selfish than the rest of men. So Mr. Laxley said—just like the jealousy of men—they needn't talk of women ! I'm sure nobody can tell what we have to put up with. We mustn't look out of this eye, or out of the other, but they're up and—oh, dear me ! there's such a to-do as never was known—all for nothing ! '
"'My good girl!' said Evan, recalling her to the subject-matter with all the patience he could command.
"`Where was I?' Polly travelled meditatively back. `I do feel a little cold.'"
Evidently, recalled thoughts—memory—need direction and guidance. What is it that guides? It is the thought about which we are conversing—the central idea around which related memories should cluster. The material from which this selection is made comes, of course, from past experience; but experience is always varied. Every idea has been connected with many others. And it is here that the purpose of the moment plays its controlling part when it is kept rigorously in mind. The failure to keep to the point—to progress in one's thinking and talking—is commonly caused by carelessly losing the thread of conversation or thought.
Naturally, much depends upon the intensity of the impressions, and for deepening the impress, repetition, recency, vividness, and the number of associations focussing upon the idea or event that is to be remembered are important. Retention, after the impression has been made, is determined by the quality of brain-tissue. Consequently, any improvement here is produced indirectly. As in other mental matters the effect of hygienic living cannot be over-estimated. A vigorous metabolism, by rapid elimination of the waste products caused by wear and tear, and by rebuilding the nervous structures, continually rejuvenates the tissues and keeps them "fit." The effect of this is appreciated when destruction of tissue exceeds construction, as when one becomes "worn out" from overwork; lack of exercise, or from temporary fatigue. The mind, and with it the memory, then refuse to work. The psychological significance of what has been said in earlier chapters about exercise, food, and fatigue is therefore obvious.
In the last analysis, however, we must accept our brain-tissue as it is and endeavor to make the most of it. After hygienic living, improvement of memory requires conformity to rules and principles that grow out of the memory process. The purpose of the experiments cited in this chapter is to discover some of the principles inherent in memory. But before discussing these investigations it may be well to mention, briefly, a few of the facts underlying retention and recall.
The fundamental psychological law of memory is, of course, based upon association of ideas, and the investigations of retention and recall are attempts to ascertain under what conditions associations are firmly established with the least expenditure of time and energy. Stated in its simplest psychological terms the law of association is, that if two ideas have been in the mind simultaneously or in immediate succession the recurrence of one of them tends to bring the other in its train. I meet a man, for example, whom I formerly knew quite well, but whose name I can-not remember. I must recall it, however, for a friend will join us soon to whom the man must be introduced, and I do not wish to admit that I have forgotten his name. My mind runs over the period of our former acquaintance. We were together in a certain town, we had several friends in common, whose names come back as the circumstances are recalled. Events long forgotten follow one another in more or less serial order; then, quite suddenly, perhaps, as I remember a little play in which we both participated, the desired name bursts upon me. The writer has been trying to describe a bit of personal experience. It was a long series of associations and several times the name seemed about to come, but still it eluded him. Finally, however, the right clew, the event with which the name was in closest association, was reached, and then it followed as a matter of course.
Neither the statement of the "law of association," however, nor the description of the process gives the reason for the succession of thoughts or for the recall of any given idea. For this explanation it is necessary to turn to the nervous system. The connection between ideas rests, ultimately, upon a more fundamental connection between neurones, and upon increased permeability of the synapses joining these neurones. The law should, therefore, be stated in physiological terms, as follows: When two neurones have been active together or in immediate succession, the activity of one tends to excite the other to action. The synapse is the point of functional connection between neurones, and simultaneous or successive action of the two neurones decreases the resistance of their juncture. For this reason the excitation of one easily extends to the other. The change in the synapse, resulting from the passage of a nervous impulse from one neurone to another, is the physiological basis of association, as of habit. Association is much more complex than this so-called law implies, but it is not our present purpose to examine its more intricate manifestations. The important fact to observe here is that memory proceeds according to law and order.
There are, to be sure, cases in which memory seems to be independent of association. 'Ideas, at times, appear to come into the mind of their own accord. We are some-times obsessed by a word, a tune, or a face. So far as we can discover such ideas are uncaused. There is, however, in the author's opinion, no reason for assuming that this perseverative tendency—the persistence of the activity of the cells of the cortex—violates the principle of association. It is probably due to hidden associations, to similarities or contrasts of which one is not fully conscious, or to old associations which have faded to obscurity. The fact that perseveration is especially noticeable when one is fatigued supports this view. In such a condition the older, more permanently established, associations would naturally obtrude. Associations are much more numerous and controlling than we are inclined to think. Suggest almost any topic, such as anarchist, trades-unions, or walking delegate, to a friend, and you will find that he has very strong opinions, though he may never have given the ideas a moment's conscious reflection. The associations that give approval or disapproval have been formed wholly unconsciously through the influence of newspaper statements or conversations. Perseveration may therefore be explained without recourse to free ideas, for which there is at present no convincing evidence.
These apparently detached ideas are sometimes bridges over which one passes from memory to imagination. On rare occasions they offer new points of view and a great discovery may follow. The mental attitude toward the questions raised is important here, and knowledge plays an inestimable role.
Knowledge as a factor in memory has received too little attention. The more we know about a subject the more easily and accurately do we remember what we read concerning it. The reason, of course, is that we see more meaning in what we read and, because it has a richer significance, associations are more numerous and intelligible. Knowledge is also necessary for flashes of insight. This is the basis for the statement attributed to Thomas Edison, that "genius is not inspiration, but perspiration."
Adults are prone to think that memory is a matter of age. Children, they say, remember easily but maturity causes forgetfulness. Investigations,' however, do not support this view. Children seem to excel adults in rote learning, because they are more accustomed to this kind of memory work. As soon, however, as adults have had practice they surpass children. Mature persons are unwilling to submit to the drudgery of mechanical learning. They resent memorizing conjugations and declensions, or lists of words. Children, on the other hand, rather enjoy such work and frequently repeat in play what they have learned. Practice with them is more regular and persistent, and it is practice that counts in memory, as in other things.
Memory in children improves with age, though periods without improvement have been observed. These exceptions seem to occur when the development of organs and functions produces excessive drain upon the vitality. It should be mentioned, in this connection, that most of the experiments have been made with those of fourteen years or younger, and usually the memory tests were given immediately after the material had been learned. In a few instances twenty-four hours or several days intervened.
An experiment by Wessely' throws some light upon the relation between permanent memory and age in those under seventeen or eighteen. Boys were asked to write as much as they could remember of a poem which they had committed to memory a year or more before. The result showed that, so far as these boys were concerned—there were twenty-three or more in each of the six classes tested—retention gradually increased from twelve years of age to fifteen or sixteen, when it appeared to reach its maximum. Wessely also tested pupils from eleven or twelve to seventeen or eighteen, using Latin words with which they were unfamiliar. The memory test consisted in associating these words with their German equivalents. Then, twenty-four hours, one week, and one month later the German words were given, and the boys were asked to write the respective Latin equivalents. The capacity to retain and recall gradually increased from the youngest, who gave the poorest results, to those of thirteen or fourteen, who were the best. At seventeen or eighteen, again, some increase in retention was indicated.
Pohlmann' found that children fourteen years of age retain considerably more than one and one-half times as much as nine-year-olds. At about fourteen he observed a decline, due probably to physiological causes. This was followed by a second increase in capacity to retain and recall, which continued to the twentieth year, where his investigation ended. Beyond twenty years no systematic attempt has been made to follow the relation between permanent memory and age.
Meumann thinks that the limit of improvement in the ability to commit to memory is reached at about twenty-five years of age. The few tests that have been made on adults, however, indicate increasing ability much later in life. Ebbinghaus, for example, tested himself at fifty-two years of age, and found that he could learn nonsense-syllables quite as readily as he could shortly after thirty.
In a more recent investigation high-school students averaging from sixteen to seventeen years of age retained poetry better than those younger or older. With prose, however, the most efficient memory "appears much later in life, and the more abstract and difficult the material the later it appears." On the whole, this investigation sustains the earlier conclusions, that memory of material with meaning improves until the period when the mental powers in general begin to decline.
The reason for the better memory of adults is greater ability to concentrate their attention, wider knowledge, with its wealth of associations, and the will to remember as represented in their attitude toward their work. Interest in what one is doing, with its accompanying zeal to achieve results, concentrates the attention on the work and tends to eliminate disturbances. There are, of course, variations from the rule, both among adults and children. The power of concentration, the amount of reflection, and the mental type of the reader, all play their role. But it is safe to say that in the vast majority of those under forty-five or fifty who are unable to remember what they hear or read, the fault lies in the absence of endeavor.
Another preliminary question regarding memory is its relation to intelligence. Do brighter children remember better? This cannot be answered definitely. Winch' tested boys and girls ranging from eight years of age to a little over fourteen. He made two kinds of experiments. In the first set twelve consonants were read aloud. The children wrote the consonants from memory immediately after they were given. Winch found a direct relation between memory and intelligence, as indicated by success in school studies. It should not be forgotten, however, that school methods too commonly put a premium on rote-learning. It is, therefore, pertinent to ask whether a good memory of the sort investigated by these tests and good school marks do not largely overlap.
Pyle, testing the members of several college classes, found so slight a correlation as to be practically equivalent to a denial of any mutual relation. Lyon, on the other hand, concluded that "the students who rank highest in their classes and who may be classed as the most intelligent have, as a rule, the best memories." An examination of Lyon's tests, however, indicates that the differences are not sufficient to warrant a definite statement. Indeed, the investigator himself says: "The differences are not marked. Upon taking any one form of material, contrary results may be obtained."
Henderson, again, observed no correspondence between class standing and memory in the grammar-school, but he did find a correlation among older pupils. This difference was quite likely due to the increased ability of those who were older to understand the meaning of what they read or heard and to the more abundant associations.
Ebbinghaus measured the ability and memory of gymnasium pupils. Those included in his tests ranged from eleven years of age to eighteen. Three kinds of tests were used: A memory test of numbers of one syllable in varying order, an arithmetical test of simple addition and sub-traction, and a third, consisting of prose selections, suited to the ages of the different children, with occasional syllables and words omitted. The omissions were indicated by dashes, and the children were to supply the omissions so as to make sense. The results showed that the youngsters with the best memory—the numbers were to be writ-ten down in their order as soon as heard—were not the ones who displayed the most intelligence in the other tests. This investigation is more accurate than that of Winch, because the memory and intelligence tests do not overlap. They do not make demands on the same sort of ability.
Experiments made by Pohlmann also indicate that memory varies with age rather than with intelligence, but Pohlmann adds that in the great majority of cases high degrees of memory and intelligence seem to be associated. The disagreement regarding this question is probably due to the fact that there are different kinds of abilities. Good memory and unusual intelligence will then be correlated when the same or similar mental processes are involved in each. This will also explain the fact that different kinds of material produce varying results, as was found by Lyon.
When one looks over the investigations' on the comparative memory effect of seeing or hearing words, numbers, nonsense-syllables and sentences, or, again, of articulating internally what is heard or seen, one also finds much disagreement.
So far as the comparative advantage to memory of hearing or seeing is concerned, the method of presenting the material is not a certain criterion of the manner in which it will be imaged in preparation for remembering it. For example, a list of words or of dates is given to three men; one may think them in auditory images, the second in visual, and the third, again, may go through the incipient movements of pronouncing them. Most people, however, are not predominantly auditory, visual, or motor minded. They use one or another kind of imagery, according to the convenience or suggestion of the moment, influenced chiefly, of course, by the definiteness of their tendency to one or the other method of thinking what is seen or heard. The problem may be approached from two sides: first, What is the comparative efficiency of the manner of presenting material to be memorized? and, second, How is the memory material worked up for reproduction? This last involves the further question, How does the manner in which it is worked up vary with the auditory, visual, and motor minded persons, and what is the influence of the method of presentation, or the kind of material employed, in determining the answers to these questions? Unfortunately, these several problems have not always been distinguished in the investigations, and this is probably one of the causes of the disagreement.
Henmon endeavored to ascertain the effect upon retention of the several ways of presenting memory material. He used concrete nouns, numbers, and nonsense-syllables. The tests were made upon six young men and women. The auditory method of imparting the material yielded the best results in the three sorts of tests, and that too, regardless, apparently, of the imagery to which the different persons were accustomed. Kemsies, Hawkins, and von Sybel also found that what is heard is retained and reproduced better than what is seen.
Kirkpatrick, on the other hand, says that school children remember objects seen better than visual words. This agrees with the observations of various investigators that children use images of particular objects in their thinking. Miss Calkins, experimenting with college women, and substituting lantern-slides for objects, came to essentially the, same conclusion. Finzi, Muller and Schumann, Muller and Pilzecker, and Meumann found vizualizers more accurate than those of the auditory type, but Meumann thought them slower. Bigham concludes that visual and auditory memory combined greatly reduce the errors. His investigation indicates that memory is helped by calling to aid as many sorts of associations as possible, instead of limiting oneself to those that grow out of the individual's mental characteristics. An all-around developed imagery would then seem to be conducive to a good memory. Meumann, however, believes that children should first learn to utilize the memory-aids which coincide with their mental peculiarities, and that only after they have gained what advantage they can from these should they be trained to improve their memory by enlarging their memory-aids beyond these "innate" characteristics. One is inclined to agree with Meumann when recalling such instances as the school-days of Justus von Liebig. The story runs, as once related by Liebig himself, that on one occasion when the director of the gymnasium visited young Liebig's class and heard his wretched recitation, he told him that he was the plague of his teacher and the sorrow of his parents. When the director asked what so lazy and inattentive a boy could do, Liebig replied that he was going to be a chemist. At this the director laughed uproariously. Finally, Liebig's father was compelled to withdraw him from the gymnasium because he could not keep up with his class. In his mature years Liebig said that the cause of his inability to do the class work was that he had scarcely any auditory memory. He could retain little or nothing of what he heard; and his school made no provision for individual peculiarities.
The significance of these investigations of mental "types" for one's daily life and growth is best understood when one remembers that experiences in the outside world are not limited to one sense. We can usually hear, or see, or respond in a motor fashion, as we will. Consequently, individual differences are provided for without any effort on our part and commonly, also, without attention from us. Most people belong to what may be called the mixed class. They are not wholly visual, auditory, or motor. To be sure, they prefer to see, or to hear, or to write names which they wish to remember, because they retain better what comes through one particular sense-organ, or that upon which they react in a motor manner. But they are not wholly excluded from other sorts of experiences, as was Liebig. Sight plays a prominent role in most of our impressions from the outside world. Perhaps this is the reason for the predominance of visual imagery in the majority of people, not even excluding the "mixed class" to which reference has just been made. There are, of course, numerous individual variations, from the great portrait-painters who "see" the absent model sitting before them to those who mentally see little or nothing. Meumann regards the exclusively visual or auditory person as, in a certain sense, defective. A glance at two or three notable cases will be interesting in showing the occasional strong predominance of the visual and auditory bent of mind.
Inaudi and Diamandi are two reckoning memory-wonders who were investigated by Binet and Meumann. Inaudi was the son of a poor shepherd. He did not attend school until he was fourteen years of age, but at six his brother had taught him to count. His marvellous ability in reckoning was observed at seven years of age, when he could multiply two five-place numbers mentally. Later in life he was able to multiply mentally numbers each of which contained as many as 24 digits. His problems had to be given orally. So lacking was he in visual images that he was confused by the sight of the example upon which he was working. He was able to recall 42 numbers in a longer series read to him, and in twelve minutes he could learn 105 figures by hearing them repeated. In other matters his memory was poor.
Diamandi, on the other hand, employed visual images exclusively, according to Binet; visual and motor if we accept Meumann's investigation. He was the son of well-to-do Greek parents and enjoyed the school privileges of his class. His problems had to be written upon the black-board. Then, having looked at one for a few minutes, he closed his eyes and the visual representation came. Only after this reproduction of the numbers did he begin his calculation. His own statement was that he saw the numbers "as if they were photographed."
Inaudi, as has been said, was an auditory calculator, and Diamandi did his reckoning visually. The one "heard" the names of the numbers in his calculations and the other "saw" them. Meumann, however, says that he found that both used "internal speech." Inaudi had observed that hoarseness disturbed him when calculating, and a registering apparatus revealed movements of his tongue and larynx. But, at all events, the vocal movements were only aids for the auditory images of the one and for the visual images of the other.
Binet's investigation of these two calculating prodigies shows that their memories conform to the same laws as those of other people. When Inaudi's memory was assisted by the meaning of the problem it was ten times as efficient, according to Meumann, as his mechanical memory, which is essentially the same as Ebbinghaus found in the average person.
The most famous calculating memory-wonder on record is a university student by the name of Ruckle, who gave an exhibition before the Congress for Experimental Psychology at Giessen.' He was able to learn 204 figures in thirteen minutes, so that he could repeat them. Ruckle differed from Inaudi and- Diamandi in having an exceptional memory for other things than figures and numbers. He could learn a series of nonsense-syllables in less than half the time usually required. With Ruckle, however, as with others, recall was not based on mere memory. He made use of various devices which gave the figures meaning. For example, he separated them into columns, and each column served as a unit, and in remembering long numbers he divided them into their prime factors. Further than this, his method was to change what he heard into visual images. Then, as he put it, he saw the numbers as clearly as though they were written on a black-board. There are also striking examples of wonderful memories in other fields than mathematics. Mozart, after hearing but once the Miserere of Allegri, wrote it out from memory, and Beethoven produced, among other compositions, the Ninth Symphony and the Mass in D, after he became deaf.
Turning now to the methods by which memory may be made more serviceable, one of the first questions suggested is that of slow and rapid learning. In certain instances this is, of course, settled by the nervous system. Some people are born slow. But in the great majority of cases the rapidity with which one reads or studies is an acquired habit. Consequently, those who wish to make their memory more efficient will be interested in the comparative value of these two ways of working.
The opinion generally prevails that those who learn quickly forget easily, but experiments' do not sustain this view. Practically all of the investigators have found that rapid workers remember more of what they learn than those who are slow. This is true not only of immediate memory—memory tested as soon as the learning is completed—but also of permanent retention. Quantz, for example, observed, in his study of reading, that rapid readers do superior work. They retain more of the substance of what they read or hear than slow readers. Pyle tested eight young men and four women with a selection of easy prose, and, again, the fast learners had the advantage both in the time required.for the work and in the amount that they retained. Pyle also noticed that the rapid learners in the group with which he worked excelled in accuracy. Miss Norsworthy tested eighty-three students, and after a month had passed the more rapid workers remembered more of what they had committed to memory than those who had learned the assignment with more effort. Essentially the same conclusion, at least for intelligible material, was reached by Lyon.' "Those who learn quickly," he says, "remember longest if the material is logical in character. Where the material is `illogical' and is memorized by motor associations, so to speak, the converse is true."
It appears, then, from these and other experiments that, in reading or studying selections of connected thought, rapidity is economical, provided it does not exceed the speed at which the reader can get the meaning clearly. Beyond this rate haste would obviously be uneconomical. The discovery that the statement "Easy comes easy goes" is not true has far-reaching educational significance.
If a young man plans to enter business or any of the professions, for example, it is of supreme importance that he acquire the ability to tear the meaning from pages at a glance. A business man should be able to understand the report of a department manager as his eye runs it over; and a lawyer cannot be long in getting the significance of a legal document if he would win his case. Further, the amount that one must read in law, medicine, science, literature, or theology to become proficient is enormous, and it is continually increasing. The young man who hopes to reach a position of importance must learn to cover ground rapidly and to note the landmarks as he passes.
But there is still another phase of this same question. Often one consults books for a definite purpose, to secure information about a certain matter. A lawyer, for example, is looking for opinions, decisions, or analogous cases to settle a legal point. He must finger many books but he has not time to read them through. Success in this re-quires ability to get the contents of a page at a glance. He does not read it, but he must grasp the substance. Physicians have many more medical journals than they can read through if their practice is extensive. They need to see the meaning of the articles as they turn the pages.
For the lecturer, writer, or general reader who wishes to be informed, the situation is essentially the same. Scientific, historical, or other information is widely scattered through books and journals. The man who reads slowly is heavily handicapped. Rapid readers cover half a dozen books in an evening, getting much as they skim along and reading selected portions with more care. Many books are not worth reading through. Yet some of these contain valuable thoughts or facts scattered through their pages. A slow reader wastes a day finding this material, while rapid workers discover it by turning the leaves and reading pages at a glance. The writer often finds college seniors of high-class rank unable to skim a book and get its import. In some of these cases, at least, it is not slow comprehension, but rather lack of training. Like other forms of ability, this power to get meaning quickly, then to sift the information and to organize it rapidly into knowledge, improves with practice.
Despite every effort to remember, however, we still for-get. It is therefore desirable to notice the rapidity with which forgetting proceeds. Investigations' have been made with children and adults, and the results are in substantial agreement. Ebbinghaus experimented upon himself with nonsense-syllables, and found that he forgot very rapidly the first hour, proportionately less for the next seven hours, and still more slowly through the balance of the first twenty-four hours. "After a whole month fully one-fifth of the first work persisted in effect." Toward the latter part of the month the loss seemed so slight that Ebbinghaus was led "to predict that a complete vanishing of the effect of the first memorization of these series" [of nonsense-syllables] "would, if they had been left to themselves, have occurred only after an indefinitely long period of time." There is no essential difference between the findings of Ebbinghaus and later investigations. The chief disagreement is concerned with the rapidity of forgetting, immediately and soon after committing a selection to memory. Ebbinghaus' curve of forgetting appears to fall too rapidly at the outset.
Most of the tests of forgetting have been made on children or adults who learned either nonsense-syllables or selections with meaning just well enough to repeat them once without error. In the course of the investigations, however, the ability to recall was found to depend, among other things, upon the number of repetitions, upon the distribution of periods of work, and upon the number and nature of the associations formed. We accordingly turn to these memory-aids.
Repetition fixes memory. Experience shows this. If we wish to remember a name we repeat it. Investigation' of the effect of a number of repetitions have not only justified this conclusion from experience, but they have also contributed several other significant facts.
First of all, during the repetitions the mind should be actively attentive. It has been found that a combination of reading and repeating gives the best results for memory. Repeating aloud requires more effort and concentrates the attention better than silent reading. The latter is more likely to be passive. Experiments have shown, also, that memory is more than 50 per cent better if the learner is informed that the effect of the repetition will be tested than when he assumes that there will be no test.
Then, again, all repetitions are not of equal value in fixing impressions and ideas. To be sure, Ebbinghaus found that fewer repetitions were required to relearn a series of nonsense-syllables after twenty-four hours when the original number of repetitions was greater. And this saving was proportional, in a general way, to the added repetitions during the first learning, provided they did not exceed a certain number, not very accurately defined. More careful measurement of the relative efficiency of successive repetitions, however, has proved that the earlier repetitions have the greatest fixing power. This seems to be specially true in immediate memory—memory tested as soon as the learning is completed. Again, when the repetitions greatly exceed the number necessary for the first correct reproduction their efficiency gradually lessens until the gain becomes hardly measurable. Finally, it was observed that the value of repetitions varied with their distribution. This is of special importance not merely for students but also for those in the larger outside world of business and professional life. One or two questions will clear the ground.
Is it better to commit a selection of prose or poetry to memory at a single sitting, or is it advantageous to distribute our efforts over several days ? Which plan brings the desired result with the least expenditure of energy? Quite a number of investigations' have been made and there is general agreement that a distribution of periods of study gives the best results.
Ebbinghaus found, in committing nonsense-syllables to memory, that thirty-eight repetitions distributed over three days produced the same results as sixty-eight repetitions at a single sitting. Starch experimented with forty-two students. They were divided into four groups, one of which worked ten minutes at a time twice a day for six days; the second group twenty minutes at a time once a day for six days; the third worked forty minutes every other day for six days; the fourth did the entire task at one sitting of two hours. The results showed a great advantage for the shorter, more widely distributed periods. The two-hour period of work at one sitting was a bad fourth. The advantageous periods of work in this experiment seem short, but the occupation consisted in associating numbers with letters, a task which would quickly cause fatigue.
Jost carried these experiments much further than any of the other investigators and proved that neither fatigue nor inattention explains the advantage of this distribution of time. Having eliminated these two factors, he under-took to determine the best arrangement of periods of work, and he found that twenty-four repetitions, distributed over twelve days with two repetitions a day, gave better results than less distributed periods. He inclines to an even more extended distribution. If we accept Jost's view, that the advantage of distributed practice and study' lies in the greater effectiveness of old associates, Miss Perkins' results "indicate that this process of consolidation continues for at least forty-eight hours, and still longer if four or more readings are made on each day" [of practice]. Putting these investigations into general terms, the experiments show conclusively that an extensive distribution of study periods for a given piece of work is advantageous both for rapidity of learning and for permanent retention. The period favorable for one sitting and the length of intervening time will depend, among other things, upon the nature of the material and the difficulty of the task, with its accompanying fatigue. The economy of distributed study, instead of finishing what one is engaged upon and then dropping it, may then be considered established.
Jost next sought to determine why it is more advantageous to spread study or practice over several days instead of finishing the work at one sitting. He came to the conclusion that older associations—those which were established earlier—are more easily renewed than the more re-cent ones. This explanation, however, still leaves the question Why? unanswered. Some find the explanation in the effect of activity upon the nutrition of the organ exercised, and in the dropping out of interfering associations. This would be a satisfactory explanation were considerable practice always involved. But the same advantage of distributed study is observed when the selection is read but once each time. A "setting" or "fixing" of associations, on the other hand, apparently satisfies conditions. Those that are older have had more time in which to become "fixed." Since it is difficult to understand in what this "fixing" consists, unless it be the result of cerebral nervous activity, we seem at present compelled to take this view.
This explanation of the "setting" of associations during periods of rest is also indicated by experiments in re-learning skilful acts after a long interval without practice. The writer at one time acquired considerable proficiency in tossing two balls with one hand, one ball being caught and thrown while the other was in the air. More than six years later he again tested himself in this feat. In eleven days he greatly exceeded the skill which he had acquired six years before after forty-two days of arduous practice. The following curves show the progress during the original learning process, and during the test in relearning the same feat six years or more later. The curve of relearning is on the left. The rate of progress is shown at the left of the perpendiculars, and the days required in each case are indicated under the base line.' The practice in which the skill was first gained was finished six years before this memory test was made. After the conclusion of the first investigation there were five monthly tests of the effect of intermission of practice, and one memory test two years later. With these exceptions there had been no practice during the six years.
The writer has also determined the effect of intermission of practice on the typewriter? In this instance, the memory test was made more than two years after the close of the first experiments by which a certain degree of skill was attained. During the intervening two years he had not used any style of typewriter. The original investigation covered a period of fifty days, while in the memory test, two years later, only eleven days were required to reach the degree of proficiency with which the original investigation closed.
The remarkably short time needed in both of these investigations to regain the former skill, after the long interval without practice, shows the persistence of neuromuscular memory. A still more significant fact, however, is disclosed by the curves for ball-tossing given above. It will be observed that in eleven days, after six years of cessation of practice, the experimenter acquired much greater skill than that with which he closed his experiments of forty-two days, six years earlier.
It is clear that the effects of activity upon the nutrition of the organ exercised and the dropping out of interfering associations do not account for the persistence and rapid improvement of skill after such long periods of inactivity. The astonishingly rapid gain in skill in ball-tossing beyond that originally acquired indicates not only a "fixing" of nervous and muscular associations, but also, during the long interval, some sort of integrative nervous activity by which the skill was further improved. At present there is no other tenable explanation. Batson, in his investigation,' also observed improvement in skill during intervals of no practice. "After a long rest period," he says, "the subject is found to be in a condition to improve very rapidly. In some cases the results show that they have actually gained power during the rest period."
The matter of "rest periods" has wide application. Jost's investigations, as well as the others to which reference has just been made, emphasize the value of repetitions, but always with an interval between them. A book, a legal opinion, an investigation in medicine or in science, which one wishes to remember, should be read again, but not at once. It is always important, however, that the meaning be as clear as possible in the first reading, because that gives the memory a freer field; and, when it is a matter of elaboration rather than of memory alone, the reconstruction of the thoughts, as a result of cerebral processes, has a better start. Error may be corrected, but mere confusion is rarely if ever clarified without further study.
These investigations also make conscious and thoughtful a method which has been followed instinctively, or, at any rate, unconsciously. Children who "go over" the lesson just before class are acting upon this principle of distributed study. To older persons, a book, or chapter, may seem quite unintelligible when read for the first time. Upon second reading, however, after the lapse of a day or two, it is often amazing how clear the misty statements become. One now sees meaning in what before was unintelligible. Had the reader stopped with the first reading nothing would have been remembered, but now the confusion takes an orderly form. Something is indicated, however, in addition to reinforcement of memory impressions. Deepening impressions by repetition might account for the greater clearness, but this is hardly sufficient to explain the increased significance that a second reading produces after an interval of a day or so. And an intervening day gives better results than an immediate re-reading. It seems to be another illustration of the integrative nervous activity to which reference has just been made.
As a practical deduction from these investigations and observations, it may be said that students would save time and effort by keeping at least one day ahead in their studies; and the last reading, like the earlier ones, should be as rapid as following the thought permits. "Cramming" is clearly unpsychological; for accumulated repetitions within a short time have only a temporary effect. That which is learned in this way vanishes quickly.
One reason for the meagre results of cramming is that association of ideas is reduced to their sequence in the text. The wider meanings do not have a chance to assert them-selves. The bearing of associations upon memory may, perhaps, be best illustrated by comparing those at the two extremes of usefulness.
Associations may be strictly artificial and mechanical or they may be significant and interpretative. Memory systems offered for sale are of the first sort. One of these systems which has been long in the market teaches the purchaser to remember numbers by translating them into letters of words. Zero, for example, is represented by s, z, or c soft; i by t, th, or d. "All the other letters" [of the word] "are simply to fill up. Double letters in a word count only as one." This or dizzy would then stand for the number 10, and catch or gush for 76. "Now," continues the writer of the book from which we are quoting, "suppose you wish to memorize the fact that $1,000,000 in gold weighs 3,685 pounds. You go about it in this way:
"How much does $1,000,000 in gold weigh?
"Scales—statue of justice.
"Statue of justice, image of law.
"The process is simplicity itself " [mirabile dictul]. "The thing you wish to recall, and that you fear to forget, is the weight. Consequently, you cement your chain of association to the idea which is most prominent in your mental question. What do you weigh with? Scales.
"What does the mental picture of scales suggest? The statue of justice, blindfolded and weighing out award and punishment to man. Finally, what is this statue of justice but the image of law ? and the words image of law translated back from the significant letters m, g soft, f, and 1, give you 3 – 6 – 8 – 5, the number of pounds in $1,000,000 in gold."
Another of these mechanical memory systems is based upon visualization. "We must not impress upon the memory mere words, but turn our attention and train our minds to see the objects or ideas they represent, associated or combined in mental pictures," the writer of this system says. A list of a hundred "code" or "index" words is given, of which hat and hen are the first two. "See the hat and the hen in the picture together," we are told. "Do not see a hen of ordinary size, but use one strengthening principle of imagination, that of exaggeration. See a large hen four feet high. Put the black silk hat on the hen's head; now put motion into the picture, and see the hen strut about. . Knowing our index words will enable us to remember a number of varied items, such as errands." Suppose, now, that we wish to buy stamps. "We may form a picture of a large hat decorated with postage-stamps, or any clear combination of stamps and hat. The more conspicuous and striking the picture, the easier will it be to recall it." But there are also other associations in this system. "Trustees is similar in sound to rusty, so if we make trustees suggest rusty, and visualize a rusty can, the gap is bridged." Letters are to stand for figures, but it all goes back to visualization of the objects represented by the "code" words. "A combination picture of a mop and a chair will represent 3964. The danger of transposing figures, by recalling the picture as chair—mop 6439, instead of 3964, can be avoided by having the first object much larger than the second. In the case of 3964; picture the mop larger than the chair."
Of course there is no fault to find with any of this except with the whole of it. Its associative machinery is so crude that the rattle is distressing. Yet these systems are fairly representative of those on sale. That they continue and multiply indicates buyers. Consequently, some of the purchasers must feel that they receive value for the price. The explanation seems to be that if a man is sufficiently interested in improving his memory to pay an exorbitant price for a "system" he will continually keep the thought of remembering in mind. He will also observe details and repeat what he wishes to remember as he never did before the expenditure made it worth while.
The basis of a good memory is to discover valid relations, such as those of time, place, similarity and dissimilarity, cause and effect. A student may learn a mathematical or chemical formula as he would learn a series of nonsense-syllables, but he will forget it after twenty-four hours. If, however, he learns to work out the formula he will remember it. In the same way a lawyer may study court decisions as isolated facts, without reference to their causes, and he will not remember them long beyond the trial of his case. But if he study the earlier decisions out of which they grew, he will become an authority in legal matters.
The value of associations with meaning is emphasized by the results of the grotesque memory systems from which we have quoted. They show that if one works hard enough on any system of association, however mechanical and meaningless it may be, one will obtain observable results. Naturally, after paying twenty-five dollars for lessons the purchaser works at the system so as to get the value of his money. If he would be half as diligent with real relations between ideas as he is with these artificial ones, his memory would be marvellous. It should not be forgotten, however, that memory is not just one mental, or rather physiological, process which can be put through a course of training and afterward be good for all kinds of material. We have memories, not a memory. In other words, men and women have a good memory for certain kinds of facts, and a poor memory for others. A woman, for example, may be able to recall the dishes served at a score of dinners to which she was invited, yet be unable to remember any historical facts that she has read. We may, however, improve our ability to recall in certain lines by practice in those lines, but the common belief that the memory, in general, may be trained is erroneous.
The secret of memory is to think about what one wishes to remember—to think it, as we have said, in connection with other facts with which it has a spatial, temporal, causal, or other relation that gives it meaning and interprets it. Thinking presupposes a question or problem which one wishes to understand. Organization of knowledge is essential, and this organization proceeds with reference to the successive phases of the problem upon which one is working. Facts are classified under general principles which in turn explain or lead to the interpretation of the question under consideration. Information that is referred to principles is easily remembered. Darwin has told us how organization and classification of knowledge attained results with himself. His retrospect also shows the value of rethinking what has been read that memories not at first available may have a chance to assert them-selves. "I have no quickness of apprehension or wit which is so remarkable in some clever men, for instance in Huxley," he says in his Autobiography. "I am, therefore, a poor critic: a paper or book, when first read, generally excites my admiration, and it is only after considerable reflection that I perceive the weak points."
No investigations bearing directly upon the value of relations with meaning, such as cause and effect, have been made, but we know that memory depends upon association, and that the more "sense" or "meaning" one sees in what one is reading the longer it will be retained. Experiments" have shown that prose and poetry can be learned with vastly greater ease than an equal number of disconnected words, and that it will be remembered much longer. This, of course, puts the matter very inadequately.
An entire chapter, or more, can be read in a short time, and the substance repeated on the following day. To commit this to memory verbatim would require many hours.
One of the noticeable causes of memory obstruction is interfering associations. It is in the early stages of learning, however, that this interference is especially likely to produce confusion. This has been observed both in acts of muscular skill and in mental activities. When, on the other hand, proficiency in one thing has been attained, a new kind of work with opposing responses may be under-taken without observable interference. For example, one may learn to write with equal skill on two typewriters with different keyboards provided one becomes an expert with the first before starting to use the second. The significance of this in the acquisition of knowledge is obvious. A solid foundation must underlie the superstructure. Declensions, conjugations, and idiomatic constructions of one foreign language should be made automatic before beginning a second. In science and history one point of view should be thoroughly mastered before passing to other opinions and criticisms. This, of course, makes the selection of the first book to be read or studied a matter of supreme importance, because it is to be the base of operations from which the reader goes out to survey the terrain, and decide upon his strategic movements. Until he has acquired sufficient knowledge and skill to live upon the country he must constantly return to his base for supplies. Consequently, it is important that he be substantially provisioned with the fundamental necessities as an aid to memory.
Economy in memory has many points of approach, so we turn now to the manner of committing prose or poetry to memory. Is it better to read the entire selection through until it is learned, or is the work done more quickly by committing limited portions, and then combining them ? This is an important question for public speakers. The investigations' are quite decisive. In learning connected discourse of any sort, or lists of words, the economical method is to read the whole through from beginning to end until everything is memorized. The "whole" method requires fewer repetitions and less time than the "part" method. But more important than the saving of time and labor is the better retention. What is learned by the "whole" method is remembered longer and reproduced more accurately. This is true of both adults and children.
Miss Steffens found that individuals differ widely as to the manner of distributing their repetitions over the selection, but all divide it into sections with undue attention to the first part. Children especially waste time upon the first few lines by continued repetitions, and neglect the latter part. The chief reason for this practice of both adults and children is probably that learning in sections produces immediately noticeable progress while the "whole" method requires more time for the result to be observable. In addition, the human disinclination to move on—to attempt the new and strange—causes the learner to keep repeating the first part, and when he has started ahead to return again to the first few lines.
Meumann's experiments show that the time and repetitions required for memorizing a selection increase with the number of parts into which it is divided. This is true of nonsense-syllables and material with meaning. But it is more noticeable in the latter case. And the advantage of the "whole" method is greater as the amount of the material to be learned increases. Of course, since recall is the object, the final question is, Which method produces the firmest retention and the most accurate reproduction? And in these respects the "whole" method again excels.
One of the objections to . learning prose or poetry by sections is that interfering associations are established. Breaks between the sections must be connected. The end of a section is associated with its beginning instead of with the first few words of the following lines. These associations impede continuous reproduction, and time and effort must be expended in suppressing them. In the "whole" method the learning is equally distributed and the entire selection is learned uniformly. By this method, also, associations are formed between the parts, however far they may be separated. Not merely the contiguous portions, but also those remote from one another are influenced by associative bonds, so that it is not merely one word or line that recalls the next, but rather the unity of all that precedes and follows; for associations work in both directions, backward and forward. Opinions expressed on one topic by several persons, for example, tend to be recalled because of their numerous connections, but conversations with different persons on varying subjects do not recall one another, even though one immediately follows the other.
We have been considering economical memory methods, but there is another closely related question, and that is, Does the difficulty of memorizing increase proportionately with added quantities of material? Ebbinghaust concluded from his experiments with nonsense-syllables that the number of repetitions necessary for memorizing increases with enormous rapidity as the number of syllables increases. Later investigations, however, have shown that this is not altogether correct. The larger the quantity to be learned the relatively fewer repetitions are needed to memorize it. In other words, as one of the investigators puts it: "Our ability to memorize increases with the demands made upon it." One explanation of this fitting of memory to its task is probably the general tendency to adjustment. Man, as we have seen, fits his efforts to the demands—to the obstacles, to the resistance. He does not do it consciously. It is a sort of organic adaptation. Without the pressure of resistance, without something to overcome, relaxation sets in. If one's abilities are to be tested it must be through a bigger job, one that calls for the best that can be given. Then, if the man has adequate reserve power he uses it because the result is worth the effort, and it can be gained in no other way. And in memory, as in other matters, men reveal their power only in response to pressure from without.
In committing to memory a short selection one does not feel that much effort is required. With a larger amount, on the other hand, the desire to save time leads to immediate and persistent concentration of attention. The period of "warming up "—overcoming the initial disinclination—is shortened or eliminated, and the associations are strengthened. In this way the work is accomplished in a proportionately shorter time.
A survey of memory from the vantage-ground of its strength and weakness brings into view certain facts and principles. First of all, adults can no longer accuse their age for their memory failures. The mature can remember better than children if they have more knowledge—and use it. Unwillingness to recall related knowledge and to make the application cause many lapses of memory. We should, however, not try to remember everything. Not a few memory troubles begin here. Individuals make little or no distinction between memory values. Consequently, there is no mental emphasis, no outstanding facts and principles to which special attention is given and around which related matter is grouped.
We have said that much of the information which we expect to use can be readily found in books of reference. Dates, figures, statistics, and many details are matters of this sort. Engagements are of only temporary moment, and should be written down. The memory should not be needlessly encumbered. Historical information should be grouped by landmarks, for which comparatively few dates are needed. In science, conclusions and principles should be remembered. They are few, and facts are many. So their retention is not difficult; and besides, principles will usually carry with them essential details.
After material has been selected as worthy of a place in memory, the next move is to understand it. If it is historical, scientific, or literary interpretation, its comprehension will require special attention, and thinking guarantees retention. But understanding has a wider reach than is usually attributed to it. There must be reasons for the conclusions and interpretations, and these reasons involve relations with other facts—relations of cause and effect, of succession, contiguity, or similarity and contrast. These relations are interpreting connections with other ideas by which the thought that we wish to remember acquires meaning, and through this wider significance it is later recalled. Finding meaning is the basis of thinking, and thinking is fundamental to memory. Interfering associations are likely to occur and obstruct recall unless the thinking is accurate and clear.
Repetition, of course, should not be overlooked. Any-thing that is worth remembering deserves the effort that will fix it. But the repetitions should not occur at once. Intervals of a day or more should separate them, and then there should be no dallying. Surprise is often expressed at the ability of some men to remember humorous stories. The explanation, however, is that these people are inveterate story-tellers. Indeed, their stories have another humorous aspect, quite apart from their content, of which the envied narrators are not conscious. The repeating habit is so fixed that they tell the stories several times to the same persons. Therein lies their success—and failure. Repetition fixes the stories, but no effort is made to remember those to whom they have already been related.
Memory, then, is not the capricious, freakish process that it is sometimes thought to be. It is subject to law and order. Some of its laws have been determined by the investigations to which we have referred. Associations—not artificial ones but those with meaning in them—we have found to be the compelling force through which ideas are recalled. The problem of memory therefore resolves it-self into getting the right associations and "fixing" them. It is with the "fixing" process that the investigations contained in this chapter deal. In selections to be committed to memory the associations are given in the text. Here, the "whole method," with as rapid reading as clear comprehension permits, should be the plan. When, however, one reads, and tries to get the import, associations reach out further and include all related thoughts. In this case, getting the full meaning with all its implications and organizing the knowledge thus obtained are the foundation for remembering. But here, also, repetition should not be neglected, and in repeating new meaning will be discovered.
Although the impressionability and retentiveness of nerve-cells probably cannot be improved directly, indirectly they may be influenced by severe attention to what has been selected for retention. Training counts for much, and also knowledge of one's personal memory deficiency, with care for the methods of improvement. Darwin says of himself : "My memory is extensive, yet hazy: it suffices to make me cautious by vaguely telling me that I have observed or read something opposed to the conclusion which I am drawing, or, on the other hand, in favor of it; and after a time I can generally recollect where to search for my authority. So poor in one sense is my memory that I have never been able to remember for more than a few days a single date or a line of poetry." Montaigne also speaks of his poor memory, but neither with him nor with Darwin does the defect seem to have been a serious handicap in what they set themselves to accomplish. They organized their minds and work to retain the information they needed. And the more humble man with smaller tasks may do as well, if he will only apply the principles upon which a serviceable memory is built—and think.