CHAPTER XX. PERCEPTION. Perception and Sensation compared.-A pure sensation we saw above, p. 12, to be an abstraction never realized in adult life. Anything which affects our sense-organs does also more than that: it arouses processes in the hemispheres which are partly due to the organization of that organ by past experiences, and the results of which in consciousness are described as ideas which the sensation suggests. The first of these ideas is that of the thing to which the sensible quality belongs. The consciousness of particular material things present to sense is nowadays called perception. The consciousness of such things may be more or less complete; it may be of the mere name of the thing and its other essential attributes, or it may be of the thing's various remoter relations. It is impossible to draw any sharp line of distinction between the barer and the richer consciousness, because the moment we get beyond the first crude sensation all our consciousness is of what is suggested, and the various suggestions shade gradually into each other, being one and all products of the same psychological machinery of association. In the directer consciousness fewer, in the remoter more, associative processes are brought into play. Sensational and reproductive brain-processes combined, then, are what give us the content of our perceptions. Every concrete particular material thing is a conflux of sensible qualities, with which we have become acquainted at various times. Some of these qualities, since they are more constant, interesting, or practically important, we regard as essential constituents of the thing. In a general way, such are the tangible shape, size, mass, etc. Other properties, being more fluctuating, we regard as more or less accidental or inessential. We call the former qualities the reality, the latter its appearances. Thus, I hear a sound, and say 'a horse-car'; but the sound is not the horse-car, it is one of the horse-car's least important manifestations. The real horse-car is a feelable, or at most a feelable and visible, thing which in my imagination the sound calls up. So when I get, as now, a brown eye-picture with lines not parallel, and with angles unlike, and call it my big solid rectangular walnut library-table, that picture is not the table. It is not even like the table as the table is for vision, when rightly seen. It is a distorted perspective view of three of the sides of what I mentally perceive (more or less) in its totality and undistorted shape. The back of the table, its square corners, its size, its heaviness, are features of which I am conscious when I look, almost as I am conscious of its name. The suggestion of the name is of course due to mere custom. But no less is that of the back, the size, weight, squareness, etc. Nature, as Reid says, is frugal in her operations, and will not be at the expense of a particular instinct to give us that knowledge which experience and habit will soon produce. Reproduced attributes tied together with presently felt attributes in the unity of a thing with a name, these are the materials out of which my actually perceived table is made. Infants must go through a long education of the eye and ear before they can perceive the realities which adults perceive. Every perception is an acquired perception. The Perceptive State of Mind is not a Compound. There is no reason, however, for supposing that this involves a 'fusion of separate sensations and ideas. The thing perceived is the object of a unique state of thought; due no doubt in part to sensational, and in part to ideational currents, but in no wise 'containing' psychically the identical 'sensations' and images which these currents would sev 314 erally have aroused if the others were not simultaneously there. We can often directly notice a sensible difference in the consciousness, between the latter case and the former. The sensible quality changes under our very eye. Take the already-quoted catch, Pas de lieu Rhône que nous: one may read this over and over again without recognizing the sounds to be identical with those of the words paddle your own canoе. As the English associations arise, the sound itself appears to change. Verbal sounds are usually perceived with their meaning at the moment of being heard. Sometimes, however, the associative irradiations are inhibited for a few moments (the mind being preoccupied with other thoughts), whilst the words linger on the ear as mere echoes of acoustic sensation. Then, usually, their interpretation suddenly occurs. But at that moment one may often surprise a change in the very feel of the word. Our own language would sound very different to us if we heard it without understanding, as we hear a foreign tongue. Rises and falls of voice, odd sibilants and other consonants, would fall on our ear in a way of which we can now form no notion. Frenchmen say that English sounds to them like the gazouillement des oiseaux-an impression which it certainly makes on no native ear. Many of us English would describe the sound of Russian in similar terms. All of us are conscious of the strong inflections of voice and explosives and gutturals of German speech in a way in which no German can be conscious of them. This is probably the reason why, if we look at an isolated printed word and repeat it long enough, it ends by assuming an entirely unnatural aspect. Let the reader try this with any word on this page. He will soon begin to wonder if it can possibly be the word he has been using all his life with that meaning. It stares at him from the paper like a glass eye, with no speculation in it. Its body is indeed there, but its soul is fled. It is reduced, by this new way of attending to it, to its sensational nudity. We never before attended to it in this way, but habitually got it clad with its meaning the moment we caught sight of it, and rapidly passed from it to the other words of the phrase. We apprehended it, in short, with a cloud of associates, and thus perceiving it, we felt it quite otherwise than as we feel it now divested and alone. Another well-known change is when we look at a landscape with our head upside-down. Perception is to a certain extent baffled by this manoeuvre; gradations of distance and other space-determinations are made uncertain; the reproductive or associative processes, in short, decline; and, simultaneously with their diminution, the colors grow richer and more varied, and the contrasts of light and shade more marked. The same thing occurs when we turn a painting bottom-upward. We lose much of its meaning, but, to compensate for the loss, we feel more freshly the value of the mere tints and shadings, and become aware of any lack of purely sensible harmony or balance which they may show. Just so, if we lie on the floor and look up at the mouth of a person talking behind us. His lower lip here takes the habitual place of the upper one upon our retina, and seems animated by the most extraordinary and unnatural mobility, a mobility which now strikes us because (the associative processes being disturbed by the unaccustomed point of view) we get it as a naked sensation and not as part of a familiar object perceived. Once more, then, we find ourselves driven to admit that when qualities of an object impress our sense and we thereupon perceive the object, the pure sensation as such of those qualities does not still exist inside of the perception and form a constituent thereof. The pure sensation is one thing and the perception another, and neither can take place at the same time with the other, because their cerebral conditions are not the same. They may resemble each other, but in no respect are they identical states of Perception is of Definite and Probable Things.-The chief cerebral conditions of perception are old paths of association radiating from the sense-impression. If a certain impression be strongly associated with the attributes of a certain thing, that thing is almost sure to be perceived when we get the impression. Examples of such things would be familiar people, places, etc., which we recognize and name at a glance. But where the impression is associated with more than one reality, so that either of two discrepant sets of residual properties may arise, the perception is doubtful and vacillating, and the most that can then be said of it is that it will be of a PROBABLE thing, of the thing which would most usually have given us that sensation. In these ambiguous cases it is interesting to note that perception is rarely abortive; some perception takes place. The two discrepant sets of associates do not neutralize each other or mix and make a blur. What we more commonly get is first one object in its completeness, and then the other in its completeness. In other words, all brain-processes are such as give rise to what we may call FIGURED consciousness. If paths are shot-through at all, they are shot-through in consistent systems, and occasion thoughts of definite objects, not mere hodge-podges of elements. Even where the brain's functions are half thrown out of gear, as in aphasia or dropping asleep, this law of figured consciousness holds good. A person who suddenly gets sleepy whilst reading aloud will read wrong; but instead of emitting a mere broth of syllables, he will make such mistakes as to read supper-time' instead of 'sovereign,' 'overthrow' instead of opposite,' or indeed utter entirely imaginary phrases, composed of several definite words, instead of phrases of the book. So in aphasia: where the disease is mild the patient's mistakes consist in using entire wrong words instead of right ones. It is only in grave lesions that he becomes quite inarticulate. These facts show how subtle is the associative link; how delicate |