Psychologists have of course gone very deeply into the question of what the causes of association may be; and some of them have tried to show that contiguity and similarity are not two radically diverse laws, but that either presupposes the presence of the other. I myself am disposed to think that the phenomena of association depend on our cerebral constitution, and are not immediate consequences of our being rational beings. In other words, when we shall have become disembodied spirits, it may be that our trains of consciousness will follow different laws. These questions are discussed in the books on psychology, and I hope that some of you will be interested in following them there. But I will, on the present occasion, ignore them entirely; for, as teachers, it is the fact of association that practically concerns you, let its grounds be spiritual or cerebral, or what they may, and let its laws be reducible, or non-reducible, to one. Your pupils, whatever else they are, are at any rate little pieces of associating machinery. Their education consists in the organizing within them of determinate tendencies to associate one thing with another,—impressions with consequences, these with reactions, those with results, and so on indefinitely. The more copious the associative systems, the completer the individual's adaptations to the world.
The teacher can formulate his function to himself therefore in terms of 'association' as well as in terms of 'native and acquired reaction.' It is mainly that of building up useful systems of association in the pupil's mind. This description sounds wider than the one I began by giving. But, when one thinks that our trains of association, whatever they may be, normally issue in acquired reactions or behavior, one sees that in a general way the same mass of facts is covered by both formulas.
It is astonishing how many mental operations we can explain when we have once grasped the principles of association. The great problem which association undertakes to solve is, Why does just this particular field of consciousness, constituted in this particular way, now appear before my mind? It may be a field of objects imagined; it may be of objects remembered or of objects perceived; it may include an action resolved on. In either case, when the field is analyzed into its parts, those parts can be shown to have proceeded from parts of fields previously before consciousness, in consequence of one or other of the laws of association just laid down. Those laws run the mind: interest, shifting hither and thither, deflects it; and attention, as we shall later see, steers it and keeps it from too zigzag a course.
To grasp these factors clearly gives one a solid and simple understanding of the psychological machinery. The 'nature,' the 'character,' of an individual means really nothing but the habitual form of his associations. To break up bad associations or wrong ones, to build others in, to guide the associative tendencies into the most fruitful channels, is the educator's principal task. But here, as with all other simple principles, the difficulty lies in the application. Psychology can state the laws: concrete tact and talent alone can work them to useful results.
Meanwhile it is a matter of the commonest experience that our minds may pass from one object to another by various intermediary fields of consciousness. The indeterminateness of our paths of association in concreto is thus almost as striking a feature of them as the uniformity of their abstract form. Start from any idea whatever, and the entire range of your ideas is potentially at your disposal. If we take as the associative starting-point, or cue, some simple word which I pronounce before you, there is no limit to the possible diversity of suggestions which it may set up in your minds. Suppose I say 'blue,' for example: some of you may think of the blue sky and hot weather from which we now are suffering, then go off on thoughts of summer clothing, or possibly of meteorology at large; others may think of the spectrum and the physiology of color-vision, and glide into X-rays and recent physical speculations; others may think of blue ribbons, or of the blue flowers on a friend's hat, and proceed on lines of personal reminiscence. To others, again, etymology and linguistic thoughts may be suggested; or blue may be 'apperceived' as a synonym for melancholy, and a train of associates connected with morbid psychology may proceed to unroll themselves.
In the same person, the same word heard at different times will provoke, in consequence of the varying marginal preoccupations, either one of a number of diverse possible associative sequences. Professor Münsterberg performed this experiment methodically, using the same words four times over, at three-month intervals, as 'cues' for four different persons who were the subjects of observation. He found almost no constancy in their associations taken at these different times. In short, the entire potential content of one's consciousness is accessible from any one of its points. This is why we can never work the laws of association forward: starting from the present field as a cue, we can never cipher out in advance just what the person will be thinking of five minutes later. The elements which may become prepotent in the process, the parts of each successive field round which the associations shall chiefly turn, the possible bifurcations of suggestion, are so numerous and ambiguous as to be indeterminable before the fact. But, although we cannot work the laws of association forward, we can always work them backwards. We cannot say now what we shall find ourselves thinking of five minutes hence; but, whatever it may be, we shall then be able to trace it through intermediary links of contiguity or similarity to what we are thinking now. What so baffles our prevision is the shifting part played by the margin and focus—in fact, by each element by itself of the margin or focus—in calling up the next ideas.
For example, I am reciting 'Locksley Hall,' in order to divert my mind from a state of suspense that I am in concerning the will of a relative that is dead. The will still remains in the mental background as an extremely marginal or ultra-marginal portion of my field of consciousness; but the poem fairly keeps my attention from it, until I come to the line, "I, the heir of all the ages, in the foremost files of time." The words 'I, the heir,' immediately make an electric connection with the marginal thought of the will; that, in turn, makes my heart beat with anticipation of my possible legacy, so that I throw down the book and pace the floor excitedly with visions of my future fortune pouring through my mind. Any portion of the field of consciousness that has more potentialities of emotional excitement than another may thus be roused to predominant activity; and the shifting play of interest now in one portion, now in another, deflects the currents in all sorts of zigzag ways, the mental activity running hither and thither as the sparks run in burnt-up paper.
One more point, and I shall have said as much to you as seems necessary about the process of association.
You just saw how a single exciting word may call up its own associates prepotently, and deflect our whole train of thinking from the previous track. The fact is that every portion of the field tends to call up its own associates; but, if these associates be severally different, there is rivalry, and as soon as one or a few begin to be effective the others seem to get siphoned out, as it were, and left behind. Seldom, however, as in our example, does the process seem to turn round a single item in the mental field, or even round the entire field that is immediately in the act of passing. It is a matter of constellation, into which portions of fields that are already past especially seem to enter and have their say. Thus, to go back to 'Locksley Hall,' each word as I recite it in its due order is suggested not solely by the previous word now expiring on my lips, but it is rather the effect of all the previous words, taken together, of the verse. "Ages," for example, calls up "in the foremost files of time," when preceded by "I, the heir of all the"—; but, when preceded by "for I doubt not through the,"—it calls up "one increasing purpose runs." Similarly, if I write on the blackboard the letters A B C D E F,... they probably suggest to you G H I.... But, if I write A B A D D E F, if they suggest anything, they suggest as their complement E C T or E F I C I E N C Y. The result depending on the total constellation, even though most of the single items be the same.
My practical reason for mentioning this law is this, that it follows from it that, in working associations into your pupils' minds, you must not rely on single cues, but multiply the cues as much as possible. Couple the desired reaction with numerous constellations of antecedents,—don't always ask the question, for example, in the same way; don't use the same kind of data in numerical problems; vary your illustrations, etc., as much as you can. When we come to the subject of memory, we shall learn still more about this.