Sensory perception

“ There is a greater distinction between the two than between Sensation, the reaction of a sensory organ, and Perception, the216 combined result of sensory and cerebral reactions; or than that between Contractility, the property of the muscles, and Flying, the function of a particular group of muscles. It is not possible to have Consciousness without Sensibility; but perfectly possible to have Sensations without Consciousness. ”

“ Moreover, because these mental and bodily activities, being our own, can be rehearsed in what we call our memory without the repetition of the sensory stimulations which originally started them, and even in the presence of different ones.
In terms of mental science, colour and sound, like temperature, texture, taste and smell, are sensations; while shape is, in the most complete sense, a perception. This distinction between sensation and perception is a technicality of psychology ”

“ In the dog smell is mainly the determining factor, but the functioning of other senses are requisite to form secondary sensory elements; here too the: moment is made up of many series of various sense-elements. In the bird, in the ape, in the man, sight is the chief element in perception, but the percept arises not from visual elements alone, but from a synthesis of a multitude of elements coming from other sense-organs the visual elements often taking the lead. ”

“ In perceiving the chair yonder only the visual sensations constitute the true sensory groups that form the nucleus of the percept. The other psychic groups that are crystallized round the percept, such as weight, resistance, volume, size, shape, distance are really visuo-tacto motor groups they are largely tacto-muscular groups tinged by the sensory quality of the nucleus ”

“ When we perceive a passing automobile, our visual sensations are correlated by us with the activity of the visual centres in the back of the brain. We have in like manner learned to associate the auditory sensations involved in the experience with the auditory centres at the sides of the brain. Because we associate these and other sensations involved in this case of perception with parts of the brain separated spatially, temporally, and materially by us, we are not led to sunder the unitary process of perception of which these sensory elements are aspects. ”

“ These sensory nerves and centres of perception change the modes of the external stimuli conformably with their own nature; they give to these their particular colouring, as different wind-instruments played by the same person give forth different shades of sound with the same force of breath. The centres forming representations modify in their turn the actual relation of the phenomena to each other, in that they bring some into stronger relief, and neglect others of really equal value. ”

“ But the presence of the visual sensory area is not enough to give the visual perception of facts, nor is the presence of the auditory sensory area enough to give auditory perception. The cortical regions adjacent to the sensory areas are necessary for perception; if they are destroyed, the individual may still see, but not know the objects seen ”

“ A sensation or image then may be followed by any series of images without the intermediacy of external excitations and peripheral physiological processes. A sensation, however, cannot be followed by a series of sensations without the intermediacy of external stimulations. A sensation can only be initiated by its own appropriate stimulus and by its own specialized peripheral physiological processes. ”

“ In other words, l just as the organism is not simply an integrated compound of cells, tissues and organs, but all those lower units go to form the higher living unit, the life of the organism as a whole, so we may say that the sensory elements are not the same as the percept, they are anatomically found, on the autopsy of the percept,―the sensory elements are the lower units that help to form the it higher unit, the living percept. ”

“ In order that the ‘not-I’ should in this way prevail over the ‘I,’ the sensory nerves must properly conduct the external impressions, the cerebral centres of perception must be sensitive to the excitations of the sensory nerves, the highest centres must develop, in a sure, rapid and vigorous manner, the perceptions into ideas, unite these into conceptions and judgments, and, on occasion, transform them into acts of volition and motor impulses. ”

“ The sensory characteristics are profoundly modified in the synthesis, so much so that they cannot be directly discerned and can only be discovered by patient study. The elements do not exist freely, they are bound up in one indissoluble union of the percept. ”

“ As long as the visual stimulus operates as a stimulus on its own account, there is no apprehension, no noting, of color or light at all. To much the greater portion of sensory stimuli we react in precisely this wholly non-cognitive way. ”

“ When our sense organs are stimulated, the stimulus is conveyed by means of sensory nerves to the brain and there gives rise to sensation, the sense organs are sensitive to various kinds of stimuli, the stimulus to the eyes gives the sensation of sight, to the ears the sensation of sound and so on. ”

“ Many sensations we know nothing about; when we become aware of our sensations it is because communications are sent by nerve fibres, acting as telegraph wires, from the sensorium to the thinking brain, and this happens when we give our attention to any one of the multitudinous messages carried by the sensory nerves. ”

“ For this reason, I think, we must suppose that certain sense-stimuli and combinations of stimuli not only produce in the sensory areas of the brain the appropriate sensations, but that their effects are prolonged, overflowing into the motor channels and there causing a total reaction of the organism, the conscious aspect of which is a vague feeling. The organic resonance is too slight and diffuse to produce a true emotion ”

“ So far as these experiments go there appear to be at least four sensory factors of importance in the formation of a simple labyrinth habit: the chemical sense, touch, vision and the muscle sense. That the chemical sense and touch are valuable guiding senses is evident from even superficial observation, and of the importance of vision and the muscle sense we are certain from the experimental evidence at hand. ”

“ The idea or image bears the same relation to the sensation as a photograph bears to the original, or rather as a symbol to the thing it represents. Ideas, images, representations substitute, represent sensations, but they are not sensations. A sensory process is fundamentally different. A sensation is not an intense idea, nor is an idea a weak sensation. Ideas differ far more qualitatively from sensations than visual sensations, for instance, differ from olfactory sensations. ”

“ The hardness, the smoothness, the bodily resistance are perceived by the visual sense and are visual, but as such they, of course, differ from the sensations experienced by their appropriate sense organs, as when for instance the same sensations are given by touch or by muscular and kinesthetic sensations. Those muscular and tacto-motor sensations appearing as visual are not memory-images, but they are actual sensations, they are secondary sensations; they are secondary sensory elements which give the fullness of content to the percept, having visual sensory elements as its nucleus. ”

“ Thus, when a sensation of light instead of giving rise to a subsequent idea gives rise to a sensation of sound, for instance, we have the phenomenon of secondary sensation. Here the secondary sensations stand out free and distinct, but they are really always present in our ordinary perceptive experiences as bound up secondary sensory elements, as secondary sensations grouped round primary sensations. ”

“ The secondary sensory elements are not images, nor ideas, nor representations, different terms employed for the same state by various writers, the secondary elements of the percept are essentially sensations. Now sensations are qualitatively different from images, ideas or representations. The image of a light does not shine, the idea of a voice does not sound, and the representation of a perfume does not smell. A sensation, or presentation as it is sometimes termed, differs from an image or representation qualitatively, fundamentally. ”

“ If we inspect the percept more closely, we find that there is some important difference in the character of the various constituent sensory elements. The central elements forming the nucleus of the percept are given directly by the sense-organ stimulated by its appropriate sensory stimuli, while the subordinate sensory elements are given indirectly,―they cannot be traced to appropriate sensory stimuli exciting those particular sense-organs on the activity of which those subordinate elements depend for their manifestation. ”

“ In this new section we by no means cut loose from what is sensory in a subjective sense, for of course we become conscious of our own movements only through the sensory paths of sight and what is collectively called touch, chiefly sensations of contact, and tendon and joint sensations. ”

“ Another difference was that The Brain translated all its sensory apperceptions into visual form, i.e. into the language best understood by Man, the eye being Man's most highly developed sensory organ. ”

“ The man is insensible to sensory impressions made through the ear, the nose, the tongue, and, to a great extent, the eye; nor is he susceptible of pain from causes operating during his abnormal state. Nevertheless, it is possible so to act upon his tactile apparatus, as to give rise to those molecular changes in his sensorium, which are ordinarily the causes of associated trains of ideas. ”

“ We are here speaking of sensations, or of perceptions arising from our bodily structure; and to these perceptions it is plainly necessary that there should be a chain of communication between the part of the body affected, and the sensorium, or seat of perception in the brain. I remember being amused with the surprise of an intelligent little girl, who complained of a sore finger, and a pain “in the finger,” on hearing for the first time that the pain was not “in her finger,” but in her own perception of it. ”

“ By primary, sensory experience is meant our immediate, direct knowledge of any aspect of the world. In this field of our conscious life, we are entirely dependent upon sense organs and nerves and brain. Injuries to the eyes destroying their power to perform their ordinary work, or injuries to the optic nerve or to the visual center in the brain, make it impossible for us to see.
These facts are so self-evident that it seems useless to state them. One has but to hold his hands before his eyes to convince himself that the mind sees by means of eyes, which are physical sense organs. ”

“ It may be also of practical money value to the printer to know such facts, and to always be conscious of a fact more likely to be of practical use, namely, that the sensation of color is produced upon our sensory nerves in a manner closely analogous to that which produces the sensation of harmony: by ether waves set in motion in a different way. These sensory nerves are the most57 easily entered avenues to our pleasurable sensations; far more delicate and responsive than the different brain organs to the more obvious consciousnesses, as personal regard and literary appreciation, etc. ”

“ For illustration, it is perfectly evident that we can not understand what is taking place in an organ for receiving sensory impressions without first understanding its mechanism and the nature of the connections between it and the central part of the nervous system. ”

“ What is required will be found if we turn our attention from the sensory qualities of the imagery to the more fundamental qualities upon which its efficacy in modifying the rest of the experience depends. It has been urged above that images which are different in their sensory qualities may have the same effects. ”

“ We found that when a sense organ is stimulated by its appropriate type of stimulus, this stimulation travels through the sensory nerves and sets up an excitation in the brain. This excitation in the brain gives us sensation. We see if the eye is stimulated. ”

“ The second finds that whatever stimulus is applied to a sensory nerve, the nerve always reacts with the same sort of sensation, and conversely, that if the same stimulus affects different nerves, the sensations will belong to different senses. The psychologist, lastly, finds that all the data of sense are instinctively and invariably referred to external existences, and never to the observer's internal condition. ”

“ For a sound stimulus awakens not only a sensory process in the ear, the correlative of which is a sensation, but also incipient motor reactions, which, if carried out, would be an emotion, but which, being too slight and diffuse, produce only what we call a mood. Every sensation has a meaning for the organism in an environment where it has constantly to be on its guard for danger or assistance; every sensation is therefore connected with the mechanism of reaction, with its attendant emotions. ”

“ Sensations of touch and sight have in a pre-eminent degree a certain peculiar continuity which differentiations of extensity entail, and which we shall have presently to consider further under the title of local signs. The various sensations classed together as organic, hunger, thirst, physical pain, &c., are left to the physiologist to describe.
Our motor presentations contrast with the sensory by their want of striking qualitative differences. They are divided Movements. ”