§ 2. Good and Bad Memory. — The marks of a good memory are, (1) The rapidity with which the power of recalling an experience is acquired; (2) The length of time during which the power of remembering lasts without being refreshed; (3) The rapidity and accuracy of the actual revival. Some persons can learn quickly and easily, but soon forget; others take a long time to learn, but also retain for a long time what they have once learned. Even when memory is retentive, so that what is once learned is not easily forgotten, there may yet be slowness and hesitancy in the actual process of reminiscence.

As a fourth mark of good memory, we may mention its serviceableness, or in other words the readiness with which it reproduces what is relevant to the prevailing interest of the moment. A memory may be extremely extensive without being in this sense serviceable. Dominic Sampson's mind, for instance, was like "the magazine of a pawnbroker, stowed with goods of every description, but so cumbrously piled together, and in such total disorganisation, that the owner can never lay his hands on any one article at the moment he has occasion for it."* Those who cram for examinations often realise this in a painful manner. So long as the questions are straightforward, so that the answers may be taken directly from the books they have used, they may find no difficulty. But as soon as a question is asked which requires them to record their acquired knowledge in a different order and manner from that in which it is given in their textbook, they break down. The materials for an answer may really be contained in what they have learned, and yet they may not be able to recall what is wanted, because the particular question has never been associated in their minds with the particular answer.

* Guy Mannering, ch. xxxix.

The rapidity with which the power of recalling is acquired depends to a large extent on the keenness of the interest attaching to the original experience. Much that attracts attention only transiently and faintly fails to be remembered at all. It is to be noted that we tend to remember, not only what is in itself interesting, but also connected circumstances which may in themselves have little interest. A young child takes little interest in the alphabet for its own sake, but if the letters are made of gingerbread, it is more likely to remember them. So far as the power of acquiring a memory does not depend on interest, it must be set down to the account of congenital constitution. But it may be doubted how far congenital constitution gives the power of remembering without giving capacity for interest in what is remembered. Mozart as a boy of fourteen years old could write down from memory an extremely complex piece of music after having heard it only once; but the musical genius of Mozart caused him to take a most intense and absorbing interest in the actual hearing. Some idiots show remarkable power of memory. They can for instance repeat long lists of disconnected words which they have heard only once. Probably this is connected with the fact that the range of interest in the idiot is excessively narrow and correspondingly concentrated. They are scarcely capable of apprehending any relations except those of bare contiguity in time and space. Hence their remarkable powers of recalling series of objects which are only connected in this manner. There are no other divergent lines of association to compete with those which are formed by the mere sequence of external impressions.

Differences in the length of time during which the power of recall is retained also depend largely on interest. It is to be remarked that the kind of interest which facilitates the acquisition of memory is not necessarily the same as that which is most effective in causing its permanent retention. The barrister learns the facts bearing on a particular case, but rapidly forgets many of them, which have only a transient interest, when the case is over. The properly legal aspects of the case, on the contrary, will tend to be retained because he has in them a permanent interest.

Another very important factor in determining duration of the power of recall is the frequency with which the remembered experience has been repeated. A boy learning a passage by heart will go over it again and again until he has thoroughly stamped it in. Differences in the retentiveness of memory which are not traceable either to interest or to frequent repetition must be referred to congenital constitution. Here again it is doubtful how far congenital constitution can favour memory without favouring interest.

The conditions on which serviceableness depends are of a different kind. A man who can readily recall what he needs at the time he needs it is said to have his knowledge wellarranged or organised. The mass of his acquirements may be much smaller than that of another man whose knowledge takes the form of cumbrous and disjointed erudition. Yet his memory may be incomparably more effective both for practical and theoretical purposes, and even in the answering of examination papers. To understand the distinction we must note that a man may be perfectly able to call something to mind when a certain prompting cue is given, and quite unable to do so in the absence of this cue. I may be quite able to recall a line of verse if I have first heard or recalled the previous lines; but I may be quite unable to recall the same line of verse as a quotation illustrating some point in which I am interested at the moment. The reason is that I have never thought of the meaning of this line of verse, or of similar objects, in connexion with this particular point or similar points. It is not necessary that the particular line of verse should have been thought of in a special connexion for it to be recalled in this connexion. All that is necessary is that the general kind of relation involved should be more or less familiar to the mind. I may for instance wish to illustrate the fact that in poetic metaphor the connexion between the metaphorical expression and the reality which it expresses is often identity in the form of combination of a complex whole rather than identity in the nature of its material constituents. For this purpose I may quote Tennyson's line,

"A doubtful throne is ice in summer seas."

A throne is not in the least like ice, nor the dangers to which it is exposed like the warmth of summer seas. There is only analogy of relation. Now for this line of Tennyson to occur to me as an illustration of my point, it is not necessary that I should have thought of it before in this connexion. But it is necessary that I should previously have thought of other similar illustrations. The more I have done this, so as to familiarise myself with this kind of mental transition, the more readily shall I be able both to recall old illustrations and to produce new ones. Thus we may say that the serviceableness of memory depends on our forming the right kind of associations. The tendency of A to recall B in a certain kind of relation, r, depends on our having previously attended to A and B in this relation, or to things similar to A and B in similar relations.