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Rh bias and so induced, like the upholders of this innervation theory, to look for evidence of subjective activity in the wrong place, have been led to doubt or to deny the reality of this activity altogether. In fact, this theory, while it lasted, tended to sustain an undue separation of so-called “sensory” from so-called “motor” presentations, as if living experience were literally an alternation of two independent states, one wholly passive and the other wholly active, corresponding to the anatomical distinction of organs of sense and organs of movement. The subject of experience or Ego does not pass to and fro between a sensorium commune or intelligence department and a motorium commune or executive, is not in successive intervals receptive and active, still less always passive, but rather always actively en rapport with an active Non-Ego, commonly called the External World.

17. In treating apart of the differentiation of our sensory and motor continua, as resulting merely in a number of

distinguishable sensations and movements, we have been compelled by the exigencies of exposition to leave out of sight another process which really advances pari passu with this differentiation, viz. the integration or synthesis of these proximately elementary presentations into those complex presentations which are called percepts, intuitions, sensori-motor reactions and the like. It is, of course, not to be supposed that in the evolution of mind any creature attained to such variety of distinct sensations and movements as a human being possesses without making even the first step towards building up this material into the most rudimentary knowledge and action. On the contrary, there is every reason to think, as has been said already incidentally, that further differentiation was helped by previous integration, that perception prepared the way for distincter sensations, and purposive action for more various movements. This process of synthesis, which is in the truest sense a psychical process, deserves some general consideration before we proceed to the several complexes that result from it. Most complexes, certainly the most important, are consequences of that principle of subjective selection whereby interesting sensations lead through the intervention of feeling to movements; and the movements that turn out to subserve such interest come to have a share in it. In this way—which we need not stay to examine more closely now—it happens that a certain sensation, comparatively intense, and a certain movement, definite enough to control that sensation, engage attention, to the more or less complete exclusion of the other less intense sensations and more diffused movements that accompany them. Apart from this intervention of controlling movements, the presentation-continuum, however much differentiated, would remain for all purposes of knowledge little better than the disconnected manifold for which Kant took it. At the same time it is to be remembered that the subject obtains command of particular movements out of all the mass involved in emotional expression only because such movements prove on occurrence adapted to control certain sensations. A long process, in which natural selection probably played the chief part at the outset—subjective selection becoming more prominent as the process advanced-must have been necessary to secure as much purposive movement—as even a worm displays. We must look to subjective interest to explain, so far as psychological explanation is possible, those syntheses of motor and sensory presentations which we call spatial perception and the intuitions of material things. For example, some of the earliest lessons of this kind seem to be acquired as we may presently see, in the process of exploring the body by means of the limbs,—a process for which grounds in subjective interest can obviously never be wanting.

Perception sometimes means only the recognition of a sensation or movement as distinct from its original presentation,

thus implying the more or less definite revival of certain residua of past experience which resembled the present. More frequently it is used as the equivalent of what has been otherwise called the “localization and projection” of sensations—that is to say, of sensations apprehended either as affections of some part of

our own body regarded as extended or as states of some foreign body beyond it. According to a former usage, strictly taken, there might be perception without any spatial presentation at all; a sensation that had been attended to a few times might be perceived as familiar. According to the latter, an entirely new sensation, provided it were complicated with motor experiences in the way required for its localization or projection, would be perceived. But as a matter of fact actual perception probably invariably includes both cases: impressions which we recognize we also localize or project, and impressions which are localized or projected are never entirely new—they are, at least, perceived as sounds or colours or aches, &c. It will, however, frequently happen that we are specially concerned with only one side of the whole process, as is the case with a tea-taster or a colour-mixer on the one hand, or, on the other, with the patient who is perplexed to decide whether what he sees and hears is “subjective,” or whether it is “real.” But there is still a distinction called for: perception as we now know it involves not only recognition (or assimilation) and localization, or “spatial reference,” as it is not very happily termed, but it usually involves “objective reference” as well. We may perceive sound or light without any presentation of that which sounds or shines; but none the less we do not regard such sound or light as merely the object of our attention, as having only immanent existence, but as the quality or change or state of a thing, an object distinct not only from the subject attending but from all presentations whatever to which it attends. Here again the actual separation is impossible, because this factor in perception has been so intertwined throughout our mental development with the other two. Still a careful psychological analysis will show that such “reification,” as we might almost call it, has depended on special circumstances, which we can at any rate conceive absent. These special circumstances are briefly the constant conjunctions and successions of impressions, for which psychology can give no reason, and the constant movements to which they prompt. Thus we receive together, e.g. those impressions we now recognize as severally the scent, colour, and “feel” of the rose we pluck and handle. We might call each a “percept,” and the whole a “complex percept.” But there is more in such a complex than a sum of partial percepts; there is the apprehension or intuition of the rose as a thing having this scent, colour and texture. We have, then, under perception to consider (a) the recognition and (b) the localization of impressions, and (c) the intuition of things.

18. The range of the terms recognition or assimilation of impressions is wide: between the simplest mental process they

may be supposed to denote and the most complex there is a great difference. The penguin that watched unmoved the first landing of man upon its lonely rock becomes as wild and wary as more civilized fowl after two or three visits from its molester: it then recognizes that featherless biped. His friends at home also recognize him though altered by years of peril and exposure. In the latter case some trick of voice or manner, some “striking” feature, calls up and sustains a crowd of memories of the traveller in the past-events leading on to the present scene. The two recognitions are widely different, and it is from states of mind more like the latter than the former that psychologists have usually drawn their description of perception. At the outset, they say, we have a primary presentation or impression P, and after sundry repetitions there remains a mass or a series of P residua, p₁p₂p₃. . . ; perception ensues when, sooner or later, Pn “calls up” and associates itself with these representations or ideas. Much of our later perception, and especially when we are at all interested, awakens, no doubt, both distinct memories and distinct expectations; but, since these imply previous perceptions, it is obvious that the earliest form of recognition, or, as we might better call it, assimilation, must be free from such complications, can have nothing in it answering to the overt judgment, Pn is a P. Assimilation involves retentiveness and differentiation, as we have seen, and prepares the way for re-presentation; but in itself there is no confronting