Every hour of our lives we call upon memory to supply us with some fact or detail from out our past. Let memory wholly fail us, and we find ourselves helpless and out of joint in a world we fail to understand. A poor memory handicaps one in the pursuit of education, hampers him in business or professional success, and puts him at a disadvantage in every relation of life. On the other hand, a good memory is an asset on which the owner realizes anew each succeeding day.

1. THE NATURE OF MEMORY

Now that you come to think of it, you can recall perfectly well that Columbus discovered America in 1492; that your house is painted white; that it rained a week ago today. But where were these once-known facts, now remembered so easily, while they were out of your mind? Where did they stay while you were not thinking of them? The common answer is, "Stored away in my memory." Yet no one believes that the memory is a warehouse of facts which we pack away there when we for a time have no use for them, as we store away our old furniture.

What is Retained.—The truth is that the simple question I asked you is by no means an easy one, and I will answer it myself by asking you an easier one: As we sit with the sunlight streaming into our room, where is the darkness which filled it last night? And where will all this light be at midnight tonight? Answer these questions, and the ones I asked about your remembered facts will be answered. While it is true that, regardless of the conditions in our little room, darkness still exists wherever there is no light, and light still exists wherever there is no darkness, yet for this particular room there is no darkness when the sun shines in, and there is no light when the room is filled with darkness. So in the case of a remembered fact. Although the fact that Columbus discovered America some four hundred years ago, that your house is of a white color, that it rained a week ago today, exists as a fact regardless of whether your minds think of these things at all, yet the truth remains as before: for the particular mind which remembers these things, the facts did not exist while they were out of the mind.

It is not the remembered fact which is retained, but the power to reproduce the fact when we require it.

The Physical Basis of Memory.—The power to reproduce a once-known fact depends ultimately on the brain. This is not hard to understand if we go back a little and consider that brain activity was concerned in every perception we have ever had, and in every fact we have ever known. Indeed, it was through a certain neural activity of the cortex that you were able originally to know that Columbus discovered America, that your house is white, and that it rained on a day in the past. Without this cortical activity, these facts would have existed just as truly, but you would never have known them. Without this neural activity in the brain there is no consciousness, and to it we must look for the recurrence in consciousness of remembered facts, as well as for those which appear for the first time.

How We Remember.—Now, if we are to have a once-known fact repeated in consciousness, or in other words remembered, what we must do on the physiological side is to provide for a repetition of the neural activity which was at first responsible for the fact's appearing in consciousness. The mental accompaniment of the repeated activity is the memory. Thus, as memory is the approximate repetition of once-experienced mental states or facts, together with the recognition of their belonging to our past, so it is accomplished by an approximate repetition of the once-performed neural process in the cortex which originally accompanied these states or facts.

The part played by the brain in memory makes it easy to understand why we find it so impossible to memorize or to recall when the brain is fatigued from long hours of work or lack of sleep. It also explains the derangement in memory that often comes from an injury to the brain, or from the toxins of alcohol, drugs or disease.

Dependence of Memory on Brain Quality.—Differences in memory ability, while depending in part on the training memory receives, rest ultimately on the memory-quality of the brain. James tells us that four distinct types of brains may be distinguished, and he describes them as follows:

Brains that are:

(1) Like marble to receive and like marble to retain.
(2) Like wax to receive and like wax to retain.
(3) Like marble to receive and like wax to retain.
(4) Like wax to receive and like marble to retain.

The first type gives us those who memorize slowly and with much heroic effort, but who keep well what they have committed. The second type represents the ones who learn in a flash, who can cram up a lesson in a few minutes, but who forget as easily and as quickly as they learn. The third type characterizes the unfortunates who must labor hard and long for what they memorize, only to see it quickly slipping from their grasp. The fourth type is a rare boon to its possessor, enabling him easily to stock his memory with valuable material, which is readily available to him upon demand.

The particular type of brain we possess is given us through heredity, and we can do little or nothing to change the type. Whatever our type of brain, however, we can do much to improve our memory by obeying the laws upon which all good memory depends.

2. THE FOUR FACTORS INVOLVED IN MEMORY

Nothing is more obvious than that memory cannot return to us what has never been given into its keeping, what has not been retained, or what for any reason cannot be recalled. Further, if the facts given back by memory are not recognized as belonging to our past, memory would be incomplete. Memory, therefore, involves the following four factors: (1) registration, (2) retention, (3) recall, (4) recognition.

Registration.—By registration we mean the learning or committing of the matter to be remembered. On the brain side this involves producing in the appropriate neurones the activities which, when repeated again later, cause the fact to be recalled. It is this process that constitutes what we call "impressing the facts upon the brain."

Nothing is more fatal to good memory than partial or faulty registration. A thing but half learned is sure to be forgotten. We often stop in the mastery of a lesson just short of the full impression needed for permanent retention and sure recall. We sometimes say to our teachers, "I cannot remember," when, as a matter of fact, we have never learned the thing we seek to recall.

Retention.—Retention, as we have already seen, resides primarily in the brain. It is accomplished through the law of habit working in the neurones of the cortex. Here, as elsewhere, habit makes an activity once performed more easy of performance each succeeding time. Through this law a neural activity once performed tends to be repeated; or, in other words, a fact once known in consciousness tends to be remembered. That so large a part of our past is lost in oblivion, and out of the reach of our memory, is probably much more largely due to a failure to recall than to retain. We say that we have forgotten a fact or a name which we cannot recall, try as hard as we may; yet surely all have had the experience of a long-striven-for fact suddenly appearing in our memory when we had given it up and no longer had use for it. It was retained all the time, else it never could have come back at all.

An aged man of my acquaintance lay on his deathbed. In his childhood he had first learned to speak German; but, moving with his family when he was eight or nine years of age to an English-speaking community, he had lost his ability to speak German, and had been unable for a third of a century to carry on a conversation in his mother tongue. Yet during the last days of his sickness he lost almost wholly the power to use the English language, and spoke fluently in German. During all these years his brain paths had retained the power to reproduce the forgotten words, even though for so long a time the words could not be recalled. James quotes a still more striking case of an aged woman who was seized with a fever and, during her delirious ravings, was heard talking in Latin, Hebrew and Greek. She herself could neither read nor write, and the priests said she was possessed of a devil. But a physician unraveled the mystery. When the girl was nine years of age, a pastor, who was a noted scholar, had taken her into his home as a servant, and she had remained there until his death. During this time she had daily heard him read aloud from his books in these languages. Her brain had indelibly retained the record made upon it, although for years she could not have recalled a sentence, if, indeed, she had ever been able to do so.

Recall.—Recall depends entirely on association. There is no way to arrive at a certain fact or name that is eluding us except by means of some other facts, names, or what-not so related to the missing term as to be able to bring it into the fold. Memory arrives at any desired fact only over a bridge of associations. It therefore follows that the more associations set up between the fact to be remembered and related facts already in the mind, the more certain the recall. Historical dates and events should when learned be associated with important central dates and events to which they naturally attach. Geographical names, places or other information should be connected with related material already in the mind. Scientific knowledge should form a coherent and related whole. In short, everything that is given over to the memory for its keeping should be linked as closely as possible to material of the same sort. This is all to say that we should not expect our memory to retain and reproduce isolated, unrelated facts, but should give it the advantage of as many logical and well grounded associations as possible.

Recognition.—A fact reproduced by memory but not recognized as belonging to our past experience would impress us as a new fact. This would mean that memory would fail to link the present to the past. Often we are puzzled to know whether we have before met a certain person, or on a former occasion told a certain story, or previously experienced a certain present state of mind which seems half familiar. Such baffling mental states are usually but instances of partial and incomplete recognition. Recognition no longer applies to much of our knowledge; for example, we say we remember that four times six is twenty-four, but probably none of us can recall when and where we learned this fact—we cannot recognize it as belonging to our past experience. So with ten thousand other things, which we know rather than remember in the strict sense.

3. THE STUFF OF MEMORY

What are the forms in which memory presents the past to us? What are the elements with which it deals? What is the stuff of which it consists?

Images as the Material of Memory.—In the light of our discussion upon mental imagery, and with the aid of a little introspection, the answer is easy. I ask you to remember your home, and at once a visual image of the familiar house, with its well-known rooms and their characteristic furnishings, comes to your mind. I ask you to remember the last concert you attended, or the chorus of birds you heard recently in the woods; and there comes a flood of images, partly visual, but largely auditory, from the melodies you heard. Or I ask you to remember the feast of which you partook yesterday, and gustatory and olfactory images are prominent among the others which appear. And so I might keep on until I had covered the whole range of your memory; and, whether I ask you for the simple trivial experiences of your past, for the tragic or crucial experiences, or for the most abstruse and abstract facts which you know and can recall, the case is the same: much of what memory presents to you comes in the form of images or of ideas of your past.

Images Vary as to Type.—We do not all remember what we call the same fact in like images or ideas. When you remembered that Columbus discovered America in 1492, some of you had an image of Columbus the mariner standing on the deck of his ship, as the old picture shows him; and accompanying this image was an idea of "long agoness." Others, in recalling the same fact, had an image of the coast on which he landed, and perchance felt the rocking of the boat and heard it scraping on the sand as it neared the shore. And still others saw on the printed page the words stating that Columbus discovered America in 1492. And so in an infinite variety of images or ideas we may remember what we call the same fact, though of course the fact is not really the same fact to any two of us, nor to any one of us when it comes to us on different occasions in different images.

Other Memory Material.—But sensory images are not the only material with which memory has to deal. We may also recall the bare fact that it rained a week ago today without having images of the rain. We may recall that Columbus discovered America in 1492 without visual or other images of the event. As a matter of fact we do constantly recall many facts of abstract nature, such as mathematical or scientific formulÆ with no imagery other than that of the words or symbols, if indeed these be present. Memory may therefore use as its stuff not only images, but also a wide range of facts, ideas and meanings of all sorts.

4. LAWS UNDERLYING MEMORY

The development of a good memory depends in no small degree on the closeness with which we follow certain well-demonstrated laws.

The Law of Association.—The law of association, as we have already seen, is fundamental. Upon it the whole structure of memory depends. Stating this law in neural terms we may say: Brain areas which are active together at the same time tend to establish associative paths, so that when one of them is again active the other is also brought into activity. Expressing the same truth in mental terms: If two facts or experiences occur together in consciousness, and one of them is later recalled, it tends to cause the other to appear also.

The Law of Repetition.—The law of repetition is but a restatement of the law of habit, and may be formulated as follows: The more frequently a certain cortical activity occurs, the more easily is its repetition brought about. Stating this law in mental terms we may say: The more often a fact is recalled in consciousness the easier and more certain the recall becomes. It is upon the law of repetition that reviews and drills to fix things in the memory are based.

The Law of Recency.—We may state the law of recency in physiological terms as follows: The more recently brain centers have been employed in a certain activity, the more easily are they thrown into the same activity. This, on the mental side, means: The more recently any facts have been present in consciousness the more easily are they recalled. It is in obedience to this law that we want to rehearse a difficult lesson just before the recitation hour, or cram immediately before an examination. The working of this law also explains the tendency of all memories to fade out as the years pass by.

The Law of Vividness.—The law of vividness is of primary importance in memorizing. On the physical side it may be expressed as follows: The higher the tension or the more intense the activity of neural centers the more easily the activity is repeated. The counterpart of this law in mental terms is: The higher the degree of attention or concentration when the fact is registered the more certain it is of recall. Better far one impression of a high degree of vividness than several repetitions with the attention wandering or the brain too fatigued to respond. Not drill alone, but drill with concentration, is necessary to sure memory,—in proof of which witness the futile results on the part of the small boy who "studies his spelling lesson over fifteen times," the while he is at the same time counting his marbles.

5. RULES FOR USING THE MEMORY

Much careful and fruitful experimentation in the field of memory has taken place in recent years. The scientists are now able to give us certain simple rules which we can employ in using our memories, even if we lack the time or opportunity to follow all their technical discussions.

Wholes Versus Parts.—Probably most people in setting to work to commit to memory a poem, oration, or other such material, have a tendency to learn it first by stanzas or sections and then put the parts together to form the whole. Many tests, however, have shown this to be a less effective method than to go over the whole poem or oration time after time, finally giving special attention to any particularly difficult places. The only exception to this rule would seem to be in the case of very long productions, which may be broken up into sections of reasonable length. The method of committing by wholes instead of parts not only economizes time and effort in the learning, but also gives a better sense of unity and meaning to the matter memorized.

Rate of Forgetting.—The rate of forgetting is found to be very much more rapid immediately following the learning than after a longer time has elapsed. This is to say that of what one is going to forget of matter committed to memory approximately one-half will fall away within the first twenty-four hours and three-fourths within the first three days. Since it is always economy to fix afresh matter that is fading out before it has been wholly forgotten, it will manifestly pay to review important memory material within the first day or two after it has once been memorized.

Divided Practice.—If to commit a certain piece of material we must go over it, say, ten different times, the results are found to be much better when the entire number of repetitions are not had in immediate succession, but with reasonable intervals between. This is due, no doubt, to the well-known fact that associations tend to take form and grow more secure even after we have ceased to think specifically of the matter in hand. The intervals allow time for the associations to form their connections. It is in this sense that James says we "learn to swim during the winter and to skate during the summer."

Forcing the Memory to Act.—In committing matter by reading it, the memory should be forced into activity just as fast as it is able to carry part of the material. If, after reading a poem over once, parts of it can be repeated without reference to the text, the memory should be compelled to reproduce these parts. So with all other material. Re-reading should be applied only at such points as the memory has not yet grasped.

Not a Memory, But Memories.—Professor James has emphasized the fact, which has often been demonstrated by experimental tests, that we do not possess a memory, but a collection of memories. Our memory may be very good in one line and poor in another. Nor can we "train our memory" in the sense of practicing it in one line and having the improvement extend equally to other lines. Committing poetry may have little or no effect in strengthening the memory for historical or scientific data. In general, the memory must be trained in the specific lines in which it is to excel. General training will not serve except as it may lead to better modes of learning what is to be memorized.

6. WHAT CONSTITUTES A GOOD MEMORY

Let us next inquire what are the qualities which enter into what we call a good memory. The merchant or politician will say, "Ability to remember well people's faces and names"; the teacher of history, "The ability to recall readily dates and events"; the teacher of mathematics, "The power to recall mathematical formulÆ"; the hotel waiter, "The ability to keep in mind half-a-dozen orders at a time"; the manager of a corporation, "The ability to recall all the necessary details connected with the running of the concern." While these answers are very divergent, yet they may all be true for the particular person testifying; for out of them all there emerges this common truth, that the best memory is the one which best serves its possessor. That is, one's memory not only must be ready and exact, but must produce the right kind of material; it must bring to us what we need in our thinking. A very easy corollary at once grows out of this fact; namely, that in order to have the memory return to us the right kind of matter, we must store it with the right kind of images and ideas, for the memory cannot give back to us anything which we have not first given into its keeping.

A Good Memory Selects Its Material.—The best memory is not necessarily the one which impartially repeats the largest number of facts of past experience. Everyone has many experiences which he never needs to have reproduced in memory; useful enough they may have been at the time, but wholly useless and irrelevant later. They have served their purpose, and should henceforth slumber in oblivion. They would be but so much rubbish and lumber if they could be recalled. Everyone has surely met that particular type of bore whose memory is so faithful to details that no incident in the story he tells, no matter however trivial, is ever omitted in the recounting. His associations work in such a tireless round of minute succession, without ever being able to take a jump or a short cut, that he is powerless to separate the wheat from the chaff; so he dumps the whole indiscriminate mass into our long-suffering ears.

Dr. Carpenter tells of a member of Parliament who could repeat long legal documents and acts of Parliament after one reading. When he was congratulated on his remarkable gift, he replied that, instead of being an advantage to him, it was often a source of great inconvenience, because when he wished to recollect anything in a document he had read, he could do it only by repeating the whole from the beginning up to the point which he wished to recall. Maudsley says that the kind of memory which enables a person "to read a photographic copy of former impressions with his mind's eye is not, indeed, commonly associated with high intellectual power," and gives as a reason that such a mind is hindered by the very wealth of material furnished by the memory from discerning the relations between separate facts upon which judgment and reasoning depend. It is likewise a common source of surprise among teachers that many of the pupils who could outstrip their classmates in learning and memory do not turn out to be able men. But this, says Whately, "is as reasonable as to wonder that a cistern if filled should not be a perpetual fountain." It is possible for one to be so lost in a tangle of trees that he cannot see the woods.

A Good Memory Requires Good Thinking.—It is not, then, mere re-presentation of facts that constitutes a good memory. The pupil who can reproduce a history lesson by the page has not necessarily as good a memory as the one who remembers fewer facts, but sees the relations between those remembered, and hence is able to choose what he will remember. Memory must be discriminative. It must fasten on that which is important and keep that for us. Therefore we can agree that "the art of remembering is the art of thinking." Discrimination must select the important out of our mental stream, and these images must be associated with as many others as possible which are already well fixed in memory, and hence are sure of recall when needed. In this way the old will always serve as a cue to call up the new.

Memory Must Be Specialized.—And not only must memory, if it is to be a good memory, omit the generally worthless, or trivial, or irrelevant, and supply the generally useful, significant, and relevant, but it must in some degree be a specialized memory. It must minister to the particular needs and requirements of its owner. Small consolation to you if you are a Latin teacher, and are able to call up the binomial theorem or the date of the fall of Constantinople when you are in dire need of a conjugation or a declension which eludes you. It is much better for the merchant and politician to have a good memory for names and faces than to be able to repeat the succession of English monarchs from Alfred the Great to Edward VII and not be able to tell John Smith from Tom Brown. It is much more desirable for the lawyer to be able to remember the necessary details of his case than to be able to recall all the various athletic records of the year; and so on.

In order to be a good memory for us, our memory must be faithful in dealing with the material which constitutes the needs of our vocations. Our memory may, and should, bring to us many things outside of our immediate vocations, else our lives will be narrow; but its chief concern and most accurate work must be along the path of our everyday requirements at its hands. And this works out well in connection with the physiological laws which were stated a little while since, providing that our vocations are along the line of our interests. For the things with which we work daily, and in which we are interested, will be often thought of together, and hence will become well associated. They will be frequently recalled, and hence more easily remembered; they will be vividly experienced as the inevitable result of interest, and this goes far to insure recall.

7. MEMORY DEVICES

Many devices have been invented for training or using the memory, and not a few worthless "systems" have been imposed by conscienceless fakers upon uninformed people. All memorizing finally must go back to the fundamental laws of brain activity and the rules growing out of these laws. There is no "royal road" to a good memory.

The Effects of Cramming.—Not a few students depend on cramming for much of their learning. If this method of study would yield as valuable permanent results, it would be by far the most sensible and economical method to use; for under the stress of necessity we often are able to accomplish results much faster than when no pressure is resting upon us. The difficulty is, however, that the results are not permanent; the facts learned do not have time to seek out and link themselves to well-established associates; learned in an hour, their retention is as ephemeral as the application which gave them to us.

Facts which are needed but temporarily and which cannot become a part of our body of permanent knowledge may profitably be learned by cramming. The lawyer needs many details for the case he is trying, which not only are valueless to him as soon as the case is decided, but would positively be in his way. He may profitably cram such facts. But those facts which are to become a permanent part of his mental equipment, such as the fundamental principles of law, he cannot cram. These he must have in a logical chain which will not leave their recall dependent upon a chance cue. Crammed facts may serve us during a recitation or an examination, but they never really become a part of us. Nothing can take the place of the logical placing of facts if they are to be remembered with facility, and be usable in thinking when recalled.

Remembering Isolated Facts.—But after all this is taken into consideration there still remain a large number of facts which refuse to fit into any connected or logical system. Or, if they do belong with some system, their connection is not very close, and we have more need for the few individual facts than for the system as a whole. Hence we must have some means of remembering such facts other than by connecting them with their logical associations. Such facts as may be typified by the multiplication table, certain dates, events, names, numbers, errands, and engagements of various kinds—all these need to be remembered accurately and quickly when the occasion for them arises. We must be able to recall them with facility, so that the occasion will not have passed by before we can secure them and we have failed to do our part because of the lapse.

With facts of this type the means of securing a good memory are the same as in the case of logical memory, except that we must of necessity forego the linking to naturally related associates. We can, however, take advantage of the three laws which have been given. If these methods are used faithfully, then we have done what we can in the way of insuring the recall of facts of this type, unless we associate them with some artificial cue, such as tying a thread around our finger to remember an errand, or learning the multiplication table by singing it. We are not to be too ready to excuse ourselves, however, if we have forgotten to mail the letter or deliver the message; for our attention may have been very lax when we recorded the direction in the first place, and we may never have taken the trouble to think of the matter between the time it was given into our keeping and the time we were to perform the errand.

Mnemonic Devices.—Many ingenious devices have been invented to assist the memory. No doubt each one of you has some way of your own of remembering certain things committed to you, or some much-needed fact which has a tendency to elude you. You may not tie the traditional string around your finger or place your watch in the wrong pocket; but if not, you have invented some method which suits your convenience better. While many books have been written, and many lectures given exploiting mnemonic systems, they are, however, all founded upon the same general principle: namely, that of association of ideas in the mind. They all make use of the same basis for memory that any of us use every time we remember anything, from the commonest event which occurred last hour to the most abstruse bit of philosophy which we may have in our minds. They all tie the fact to be remembered to some other fact which is sure of recall, and then trust the old fact to bring the new along with it when it again comes into the mind.

Artificial devices may be permissible in remembering the class of facts which have no logical associates in which we can relate them; but even then I cannot help feeling that if we should use the same care and ingenuity in carefully recording the seemingly unrelated facts that we do in working out the device and making the association in it, we should discover hidden relations for most of the facts we wish to remember, and we should be able to insure their recall as certainly and in a better way than through the device. Then, also, we should not be in danger of handing over to the device various facts for which we should discover relations, thus placing them in the logical body of our usable knowledge where they belong.

8. PROBLEMS IN OBSERVATION AND INTROSPECTION

1. Carefully consider your own powers of memory and see whether you can decide which of the four types of brain you have. Apply similar tests to your classmates or a group of school children whom you have a chance to observe. Be sure to take into account the effects of past training or habits of memory.

2. Watch in your own memorizing and also that of school children for failures in recall caused by lack of proper associations. Why is it particularly hard to commit what one does not understand?

3. Observe a class in a recitation or an examination and seek to discover whether any defects of memory revealed are to be explained by lack of (1) repetition, (2) recency, (3) vividness in learning.

4. Make a study of your own class and also of a group of children in school to discover their methods of memorizing. Have in mind the rules for memorizing given in section 5 of this chapter.

5. Observe by introspection your method of recall of historical events you have studied, and note whether images form an important part of your memory material; or does your recall consist chiefly of bare facts? In how far does this depend on your method of learning the facts in the first place?

6. Carefully consider your experience from cramming your lessons. Does the material learned in this way stay with you? Do you understand it and find yourself able to use it as well as stuff learned during a longer interval and with more time for associations to form?