When someone touches you on the arm, say, you need not act in any way in order to feel the touch. So what could possibly be the sensorimotor skill involved? The answer is that what we mean by feeling a touch, rather than say, hearing a sound or smelling a smell, is the fact that the perceiver has cognitive access to the fact that at this moment he could, if he wanted, do something which would modify the incoming sensory stimulation in a way that is consistent with touch, rather than with, say, vision, hearing or smell. Thus though no action is necessary, there are certain very particular actions that are possible and which, when they occur, must be accompanied by certain predictable results if the person is currently experiencing touch. This is what we mean by saying the person is "exercising his mastery of the touching skill": although he may not at this moment be doing anything at all, he is engaged with the object in the touching mode. Thus the person is feeling touch rather than seeing, hearing or smelling when at this moment he implicitly knows he can, for example, modulate the incoming sensory stimulation in certain predictable ways by say, slightly moving his arm, or taking away his arm, but not by moving his eyes or making a noise. Furthermore the person is feeling the touch on his arm because the incoming sensory input can be modified by moving his arm, but not, say his eyes or his foot. The touch is at this particular location on the arm because the person can, if he wishes, move his other hand to that exact location and create a similar sensation. Or he can move his eyes to that location and see someone touching him there, whereas if he moves his eyes somewhere else he will see no one touching him there. The feel has the smooth quality that it does, for example, because the person implicitly knows that the rules governing the changes that will occur if he moves his arm will be very particular and quite different to those governing what would happen if the touch were of a rough object.
Currently the sensorimotor approach to touch has not been worked out in detail. An interesting question will be to try to understand what constitutes the sensation of temperature: it is not clear what sensorimotor skills could be involved here. However empirical work on the "Rubber hand illusion" is compatible with the idea that the location at which a touch is felt is partly determined by correlations between the observer's visual input and the tactile stimulation: when you see someone stimulating a rubber hand and this stimulation correlates accurately with simultaneous tactile input on your own hand, you feel the sensation on the rubber hand. The Pinocchio illusion is a similar phenomenon where the felt size of one's nose can be artificially increased...
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Page last modified on Tuesday 18 of April, 2006 [01:11:10 UTC] by admin.