CONDITIONS OF MEMORY
A. Physical Conditions.—One of the first conditions for an effective recollection of any particular experience will be, evidently, the strength of the co-ordinations set up in the nervous system during the learning process. The permanent changes brought about in the nervous tissue as a result of conscious experience is often spoken of as the physical basis of memory. The first consideration, therefore, relative to the memorizing of knowledge is to decide the conditions favourable to establishing such nervous paths during the learning process. First among these may be mentioned the condition of the nervous tissue itself. As already seen, the more plastic and active the condition of this tissue, the more susceptible it is to receive and retain impressions. For this reason anything studied when the body is tired and the mind exhausted is not likely to be remembered. It is for the same reason, also, that knowledge acquired in youth is much more likely to be remembered than things learned late in life. The intensity and the clearness of the presentation also cause it to make a stronger impression upon the system and thus render its retention more permanent. This demands in turn that attention should be strongly focused upon the presentations during any learning process. By adding to the clearness and intensity of any impressions, attention adds to the likelihood of their retention. The evident cause of the scholar's ability to learn even relatively late in life is the fact that he brings a much greater concentration of attention to the process than is usually found in others. Repetition also, since it tends to break down any resistance to the paths which are being established in the nervous system during the learning process, is a distinct aid to retention. For this reason any knowledge acquired should be revived at intervals. This is especially true of the school knowledge being acquired by young children, and their acquisitions must be occasionally reviewed and used in various ways, if the knowledge is to become a permanent possession. A special application of the law of repetition may be noted in the fact that we remember better any topic learned, say, in four half-hours put upon it at different intervals, than we should by spending the whole two hours upon it at one time.
Another condition favourable to recall is the recency of the original experience. Anything is more easily recalled, the more recently it has been learned. The physiological cause for this seems to be that the nervous co-ordinations being recent, they are much more likely to re-establish themselves, not having yet been effaced or weakened through the lapse of time.
B. Mental Conditions.—It must be noted, however, that although there is evidently the above neural concomitant of recall, yet it is not the nervous system, but the mind, that actually recalls and remembers. The real condition of recall, therefore, is mental, and depends largely upon the number of associations formed between the ideas themselves in the original presentation. According to the law of association, different ideas arise in the mind in virtue of certain connections existing between the ideas themselves. It would be quite foreign to our present purpose to examine the theories held among philosophic psychologists regarding the principle of the association of ideas. It is evident, however, that ideas often come to our minds in consequence of the presence in consciousness of a prior idea. When we see the name "Queenston Heights," it suggests to us Sir Isaac Brock; when we see a certain house, it calls to mind the pleasant evening spent there; and when we hear the strains of solemn music, it brings to mind the memories of the dead. Equally evident is the fact that anything experienced in isolation is much harder to remember than one experienced in such a way that it may enter into a larger train of ideas. If, for instance, any one is told to call up in half an hour telephone 3827, it is more than likely that the number will be forgotten, if the person goes on with other work and depends only on the mere impression to recall the number at the proper time. This would be the case also in spite of the most vivid presentation of the number by the one giving the order or the repetition of it by the person himself. If, however, the person says, even in a casual way, "Call up 1867," and the person addressed associates the number with the Confederation of the Dominion, there is practically no possibility of the number going out of his mind. An important mental condition for recall, therefore, is that ideas should be learned in as large associations, or groups, as possible. It is for the above reason that the logical and orderly presentation of the topics in any subject and their thorough understanding by the pupil give more complete control over the subject-matter. When each lesson is taught as a disconnected item of knowledge, there seems nothing to which the ideas are anchored, and recall is relatively difficult. When, on the other hand, points of connection are established between succeeding lessons, and the pupil understands these, one topic suggests another, and the mind finds it relatively easy to recall any particular part of the related ideas.
TYPES OF RECALL
A. Involuntary.—In connection with the working of the principle of association, it is interesting to note that practically two types of recall manifest themselves. As a result of their suggestive tendency, the ideas before consciousness at any particular time have a tendency to revive old experiences which the mind may recognize as such. Here there is no effort on the part of the voluntary attention to recall the experience from the past, the operation of the law of association being, as it were, sufficient to thrust the revived image into the centre of the field of consciousness, as when the sight of a train recalls a recent trip.
B. Voluntary.—At times the mind may set out with the deliberate aim, or purpose, of reviving some forgotten experience. This is because attention is at the time engaged upon a definite problem, as when the student writing on his examination paper strives to recall the conditions of the Constitutional Act. This type is known as voluntary memory. Such a voluntary attempt at recall is, however, of the same character as the involuntary type in that both involve association. What the mind really strives for is to start a train of ideas which shall suggest the illusive ideas involved in the desired answer. Such a process of recall might be illustrated as follows:
Here a, b, c, d, e represent the forgotten series of ideas to be recalled. A, B, C, D, E represent other better known ideas, some of which are associated with the desired ones. By having the mind course over the better known facts—A, B, C, D, E, attention may finally focus upon the relation A, a, B, and thus start up the necessary revival of a, b, c, d, e.
Attention May Hinder Memory.—While active attention is thus able under proper conditions to reinforce memory, yet occasionally attention seems detrimental to memory. That such is the case will become evident from the preceding figure. If the experience a, b, c, d, e, is directly associated only with A, B, but the mind believes the association to centre in C, D, E, attention is certain to keep focused upon the sub-group—C, D, E. At an examination in history, for example, we may desire to recall the circumstances associated with the topic, "The Grand Remonstrance," and feel vaguely that this is connected with a revolutionary movement. This may cause us, however, to fix attention, not upon the civil war, but upon the revolution of 1688. In this case, instead of forcing a nervous impulse into the proper centres, attention is in reality diverting it into other channels. When, a few minutes later, we have perhaps ceased our effort to remember, the impulse seems of itself to stimulate the proper centres, and the necessary facts come to us apparently without any attentive effort.