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.Readers versed in psychological literature will have missed, in our account thus far, the usualinvocation of 'the muscular sense.' This word is used with extreme vagueness to cover allresident sensations, whether of motion or position, in our members, and even to designate thesupposed feeling of efferent discharge from the brain.We shall later see good reason to deny theexistence of the latter feeling.We have accounted.for the better part at least of the residentGet any book for free on: www.Abika.com THE PRINCIPLES OF PSYCHOLOGY125feelings of motion in limbs by the sensibility of the articular surfaces.The skin and ligamentsalso must have feelings awakened as they are stretched or squeezed in flexion or extension.AndI am inclined to think that the sensations of our contracting muscles themselves probably play assmall a part in building up our exact knowledge of space as any class of sensations which wepossess.The muscles, indeed, play an all-important part, but it is through the remote effect oftheir contractions on other sensitive parts, not through their own resident sensations beingaroused.In other words, muscular contraction is only indirectly instrumental, in giving us space-perceptions, by its effects on surfaces.In skin and retina it produces a motion of the stimulusupon the surface; in joints it produces a motion of the surfaces upon each other -- such motionbeing by far the [p.198] most delicate manner of exciting the surfaces in question.One istempted to doubt whether the muscular sensibility as such plays even a subordinate part as signof these more immediately geometrical perceptions which are so uniformly associated with it aseffects of the contraction objectively viewed.For this opinion many reasons can be assigned.First, it seems a priori improbable that suchorgans as muscles should give us feelings whose variations bear any exact proportion to thespaces traversed when they contract.As G.E.Müller says, [58] their sensory nerves must beexcited either chemically or by mechanical compression whilst the contractions last, and inneither case can the excitement be proportionate to the position into which the limb is thrown.The chemical state of the muscle depends on the previous work more than on the actually presentcontraction; and the internal pressure of it depends on the resistance offered more than on theshortening attained.The intrinsic muscular sensation are likely therefore to be merely those ofmassive strain or fatigue, and to carry no accurate discrimination with them of lengths of pathmoved through.Empirically we find this probability confirmed by many facts.The judicious A.W.Volkmanobserves [59] that:''Muscular feeling gives tolerably fine evidence as to the existence of movement, but hardly anydirect information about its extent or direction.We are not aware that the contractions of asupinator longus have a wider range than those of a supinator brevis; and that the fibres of abipenniform muscle contract in opposite directions is a fact of which the muscular feeling itselfgives not the slightest intimation.Muscle-feeling belong to that class of general sensations whichtell us of our inner states, but not of outer relations ; it does not belong among the sense-perceiving senses."E.H.Weber in his article Tastsinn called attention to the fact that muscular movements as largeand strong as those of the diaphragm go on continually without our perceiving them as motion.G.H.Lewes makes the same remark.When we think of our muscular sensations as movementsin space, it is [p.199] because we have ingrained with them in our imagination a movement on asurface simultaneously felt."Thus whenever we breathe there is a contraction of the muscles of the ribs and the diaphragm.Since we see the chest expanding, we know it as a movement and can only think of it as such.But the diaphragm itself is not seen, and consequently by no one who is not physiologicallyGet any book for free on: www.Abika.com THE PRINCIPLES OF PSYCHOLOGY126enlightened on the point is this diaphragm thought of in movement.Nay, even when told by aphysiologist that the diaphragm moves at each breathing, every one who has not seen it movingdown- ward pictures it as an upward movement, because the chest moves upward." [60]A personal experience of my own seems strongly to corroborate this view.For years I have beenfamiliar, during the act of gaping, with a large, round, smooth sensation in tile region of thethroat, a sensation characteristic of gaping and nothing else, but which, although I had oftenwondered about it, never suggested to my mind the motion of anything.The reader probablyknows from his own experience exactly what feeling I mean.It was not till one of my studentstold me, that I learned its objective cause.If we look into the mirror while gaping, we see that atthe moment we have this feeling the hanging palate rises by the contraction of its intrinsicmuscles.The contraction of these muscles and the compression of the palatine mucousmembrane are what occasion the feeling; and I was at first astonished that, coming from so smallan organ, it could appear so voluminous.Now the curious point is this -- that no sooner had Ilearned by the eye its objective space-significance, than I found myself enabled mentally to feelit as a movement upwards of a body in the situation of the uvula.When I now have it, my fancyinjects it, so to speak, with the image of the rising uvula; and it absorbs the image easily andnaturally.In a word, a, muscular contraction gave me a sensation whereof I was unable duringforty years to interpret a motor meaning, of which two glances of the eye made me permanentlythe master.To my mind no further proof is needed of the fact that muscular contraction, merelyas such, need not be perceived directly as so much motion through space.[p.200]Take again the contractions of the muscles which make the eyeball rotate.The feeling of these issupposed by many writers to play the chief part in our perceptions of extent.The space seenbetween two things means, according to these authors, nothing but the amount of contractionwhich is needed to carry the fovea from the first thing to the second [ Pobierz caÅ‚ość w formacie PDF ]