§ 5. Cognitive Continuity and Retentiveness.—The kind of continuity which we have called cognitive involves in a characteristic way the principle of retentiveness. All progress towards an end depends on the persistence of the results of previous process as the basis of succeeding change. So in this case, continuity of interest is only possible if and so far as each succeeding stage of the movement of consciousness towards an end is determined and qualified by the cumulative disposition left behind by preceding stages. At the same time this cumulative disposition is itself subject to modification by each new mode of consciousness as it emerges. Dr. Ward has given an example which partially illustrates this point.
"Suppose that in the course of a few minutes we take half a dozen glances at a strange and curious flower. We have not as many complex presentations which we might symbolise as F1, F2, F3. But rather, at first, only the general outline is noted, next the disposition of petals, stamen, etc., then the attachment of the anthers, form of the ovary, and so on......It is because the earlier apprehensions persist that the later are an advance upon them and an addition to them."*
* Locke, Essay Concerning Human Understanding, ii. x., 5.
This example excellently illustrates the working of retentiveness where there is continuity of interest. But it does so only partially and for a special case. The case adduced is one in which ''earlier apprehensions" recur as part of the same simultaneous whole with the later. The process by which the "earlier apprehensions" were originally formed is not itself repeated, inasmuch as the preparatory dispositions left behind by previous experience render it unnecessary. Hence, there is room for further advance,—for growing distinction and definition within the total presentation. But with the new distinctions the old also are combined in the same complex whole. This is one of the ways in which preformed dispositions may operate. But it is by no means the only way. The persistent traces of past experience may modify present experience and be modified by it, without reappearance of the content of the past experience in the actual moment of present consciousness.
* Article "Psychology," p. 47.
The effect of rhythmic repetition of the same stimulus is peculiarly instructive, because the external occasion of each successive impression is throughout the same, so that modifications of consciousness arising in the course of the process must be due to the working of retentiveness,to the cumulative disposition left behind by previous impressions. The sequence of physical stimuli is a, a, a,.... the sequence of mental states is a 1, a2, a3,..... The mere fact that the second a comes before consciousness as a repetition, as another of the same kind, constitutes an mportant difference between it and the first a. But, besides this, there may be a gradual modification of consciousness as the series advances, until a point is reached in which each new impression produces an effect relatively so small, in comparison with the accumulated result of previous impressions, as to be inappreciable. This is well brought out in certain experiments on what is called the "span of consciousness." The purpose of these experiments is to ascertain how many objects of a certain kind can be apprehended at once. It is found that, after hearing as many as fifteen or sixteen successive sounds at regular intervals of from 0.2 to 0.3 seconds, the subject can identify or distinguish this series as a whole from another equal or unequal to it. Counting is not admitted, and the successive sounds are of course not all simultaneously discriminated at the close of the series. A "sensationmass" alone is distinctly perceived. This is evidently a cumulative effect. Apart from special experiments in the laboratory, anyone can easily verify the statement that successive series of a rhythmic character can at their close be apprehended as a whole without mentally reproducing and discriminating in the moment of apprehension the several sequent parts which compose them. Thus, in walking, we may mentally divide our successive steps into distinct groups, and be aware without counting when one series ends and another begins. We need not even know the number of steps which are mentally connected within a single series. We may simply begin by walking a certain number of paces without counting them, and then as we proceed mark the points at which the initial series has repeated itself.
We have so far considered only the regular sequence of physically identical impressions. But the most important cases of rhythm are those in which recurrent similarity in certain respects is combined with, diversity in other respects. The rhythm of verse, which depends on a more or less uniform recurrence of long and short or of accented and unaccented syllables, may serve as an illustration. In hearing a line from Milton or Vergil we need not at any moment have more than one word actually present to consciousness. Yet this single word appears as part of the whole and is qualified in a quite specific way by its place in the whole. The sound of the word "unpremeditated" has a quite different value for consciousness in the present sentence or in a dictionary from that which it acquires in Shelley's lines:
"That from heaven, or near it, Pourest thy full heart In profuse strains of unpremeditated art."
Substitute "unstudied" for "unpremeditated," and the result is not merely one word in place of another. On the contrary, the occurrence of the wrong word is for consciousness the ruin of the whole rhythmic structure. What is true of verse is still more obviously true in the case of music. The last note of a melody may be and often is the only note of which we are aware at the moment it strikes the ear. Yet in it the entire melody is in a sense present. It comes before consciousness as part of a quite specific whole and derives a specific character from its place in that whole. The cumulative disposition generated by the ordered sequence of previous notes cooperates with the new stimulus to the organ of hearing, and the ensuing state of consciousness is the joint product of both factors mutually modifying each other. If a wrong note be struck, the whole melody is at once marred. The same happens if a note is unduly prolonged. Throughout the process the part is determined by the whole, and the whole by the part. In reading a sentence or a paragraph, when we come to the final word, the meaning of the sentence or paragraph as a whole is present to our consciousness. But it is only as a cumulative effect of previous process. What is directly given as a special datum is the last word itself and its meaning. In a similar way, the cumulative effect of one paragraph or chapter of a book qualifies and determines the meaning of another. We may set by the side of this highly complex case a very simple one. Pronounce successively the words fructify, mystify, identify, simplify; all these words terminate in the same sound. When we are just finishing or have just finished the utterance of each word, the special item of sensation before consciousness is the final sound they have in common. The preceding sounds in which they differ have vanished from consciousness; nevertheless, in each case we are aware that we have said one word and not another, that wo have said fructify and not mystify, and so on. This can only be because in each instance our consciousness, when the final sound is being pronounced, is modified by the cumulative effect of the preceding sounds.
This cumulative effect of the preceding phases of a cognitive process on the succeeding, may be called primary retentiveness, in order to distinguish it from the retentiveness which is involved in reproduction and association,processes to be discussed later on.