OUR SENSES

Rotorua Morning Post, Volume 2, Issue 245, 7 June 1932, Page 8

OUR SENSES

CAN WE TRUST THEM? RELATIONSHIP OF PHYSICAL AND MENTAL PROCESSES PHYCHOLOGICAL PUZZLES The relationship between man's physical organism and his mental processes, with special reference to the five senses were dealt with by Mr A. D. Morrison, M.A., in a lecture on psychology under the auspices of the Hastings W.E.A. Our impressions of the outer world, Mr. Morrison said, come through the senses, and the physical conditions of the senses had a direct bearing on the nature of the impressions received. Roughly, it might be said that the whole of the human psychological organic system consisted of a mass of living cells which could be classified as receptor cells and effector cells, with a third group of connector cells represented by the nervous system as such. The receptor cells were specialised to receive various kinds of stimuli, though it might be said that their function was to transmit those stimuli to the appropriate part of the nervous system, which carried out the necessary muscular or other reactions. When one considered that fundamental receptive functions of sight, hearing, touch, taste, and smell, it was found as a fundamental truth that they were all related to one another in some way. Interference with one seemed to have some effect on all the others. "If you hold your nose," said Mr. Morrison, "you cannot taste properly, and you know the truth of the familiar observation that a blind person seems to be compensated by a quickening asd further development of all the other senses." The modern scientific point of view regarded all the senses as having something in common with a primary sense of touch. Thus, rays of light were said to impinge on the reI tina of the eye, and air waves to beat on the drum of the ear. Tiny particles rubbed against the membrance of the nose, and one must touch a thing to taste it. Functioning of Senses The surface of the eye responded to rays of light, and included a muscular system which dealt with the rays in various ways. A muscular system attended the movement of the eyeballs also, and there were three pairs of such muscles working in sympathy The receptors for-sound responded to the touch of vibrations, and were in the inner ear, which was embedded in the bone of the skull. Vibration travelled to the inner ear, and then was sent on to the nervous system by way of the auditory nerve. As to taste, insoluble substances had no taste, and the stimulus must always be in a degree in liquid form. The tongue also was a muscular body. The organ of smell was the delicate mucous membrance lining the nasal cavities, and the stimulus acting on the cells were very minute particles. Kant had defined smell as taste at a distance. In addition to the five senses, there were what were known as cutaneous sensations, such as heat, cold, pain, and pressure, and there were also several bodily sensations belonging to our internals that were receptive to various stimuli. Sight was not always so dependable as it seemed to be, Mr. Morrison continued. A grey patch against a black background, for example, looked lighter than a grey patch against a white background; the evidence of the eye was not necessarily a criterion of truth. Psychologists had made interesting discoveries of the tricks that the eye could play, chiefly _ by geometrical illusions. Mr. Morrison illustrated some of these by means of diagrams. Through green glasses everything at first looked green, but by a peculiar law of compensation the effect gradually wore off, and things appeared in their natural colours. Experiments in Taste Next to sight, hearing was the source of the most satisfying experiences. In hearing, as in sight, the mind had a great deal to do with the value of what was experienced Harmony and discord seemed to have to do with the frequency of waves, and it was said that the physical explanation was that the fibres vibrate in unison with the vibrations received, so that a whole chord might set up as many vibrations in the inner ear as there were in the sound produced, so that music was analysed as it was received. The content of the individual experience determined the meaning and value of what was heard, and what was the value of the thing heard. What was heard must be linked up with what was known before if it was to be of any value. Experimenters in taste had said that there were only four kinds of taste, and that they were differently located; they were bitter sweet, sour (acid), and salt. Some parts of the tongue yielded to all stimuli and sometimes only to one. The tip of the tongue was best for sweet or salt, the back for bitter, arid the sides for sour. If the tip of the tongue were thoroughly dried, and some sugar placed on it, nothing would be tasted. Even the simple matter of taste, therefore, must be carefully regarded as being liable to mistakes. Smell resembled taste in essentials, and one interesting thing was that there was no general name for smell other than pleasant or unpleasant. The minute particles of the odorous object were carried into the nostrils by breathing, and reached the olfaetory cells, probably in the form of vapour. Smells had been classified but there had not been much agreement on the subject. To smell one kind of thing for some time would probably affect the sense of smell with regard to otheir things, and thus it had been proved that a person whose organ was fatigued by the continual smelling of tincture of iodine found it impossible to detect the odour of alcohol. Oil of camphor began by smelling like turpentine, and ended by Smelling like nutmeg. Kinaesthetic Sensations Touch was a fundamental sense, and there were all kinds of difficulties involved in a case where simplic-