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.[80] Another diagram, Fig.88, will make the matter clear.Takethe operation represented by the previous diagram at the moment when, the muscular contractionhaving occurred, the cell K is discharging forward into M.Through the dotted line p it will,according to our third hypothesis, drain S (which, in the supposed case, has just discharged intoM by the connate path P, and caused the muscular contraction), and the result is that p will nowremain as a new path open from S to K.When next S is excited from without it will tend not onlyto discharge into M, but into K as well.K thus gets excited directly by S before it gets excited bythe incoming current from the muscle; or, translated into psychic terms: when a sensation hasonce produced a movement in us, the next time we have the sensation, it tends to suggest the ideaof the movement, even before the movement occurs.[81]Get any book for free on: www.Abika.com THE PRINCIPLES OF PSYCHOLOGY381[p.586] The same principles also apply to the relations of K and M.M, lying in the forwarddirection, drains K, and the path KM, even though it be no primary or a connate path, becomes asecondary or habitual one.Hereafter K may be aroused in any way whatsoever (not as beforefrom S or from without) and still it will tend to discharge into M; or, to express it again inpsychic terms, the idea of the movement M's sensory effects will have become an immediatelyantecedent condition to the production of the movement itself.Here, then, we have the answer to our original question of how a sensory process which, the firsttime it occurred, was the effect of a movement, can later figure as the movement's cause.It is obvious on this scheme that the cell which we have marked K may stand for the seat ofeither a resident or a remote sensation occasioned by the motor discharge.It may indifferently bea tactile, a visual, or an auditory cell.The idea of how the arm feels when raised may cause it torise; but no less may the idea of some sound which it makes in rising, or of some opticalimpression which it produces.Thus we see that the 'mental cue' may belong to either of varioussenses; and that what our diagrams lead us to infer is what really happens; namely, that in ourmovements, such as that of speech, for example, in some of us it is the tactile, in others theacoustic, Effectsbild, or memory-image, which seems most concerned in starting the articulation(Vol.I.pp.54-5).The primitive 'starters,' however, of all our movements are not Effectsbilder atall, but sensations and objects, and subsequently ideas derived therefrom.Let us now turn to the more complex and serially concatenated movements which oftenest meetus in real life.The object of our will is seldom a single muscular contraction; it is almost alwaysan orderly sequence of contractions, ending with a sensation which tells us that the goal isreached.But the several contractions of the sequence are not each distinctly willed; each earlierone seems rather, by the sensation it produces, to call its follower up, after the fashion describedin Chapter VI, where we spoke of [p.587] habitual concatenated movements being due to aseries of secondarily organized reflex arcs (Vol.I.p.116).The first contraction is the onedistinctly willed, and after willing it we let the rest of the chain rattle off of its own accord.Hownow is such an orderly concatenation of movements originally learned? or in other words, howare paths formed for the first time between one motor centre and another, so that the discharge ofthe first centre makes the others discharge in due order all along the line?The phenomenon involves a rapid alternation of motor discharges and resultant afferentimpressions, for as long a time as it lasts.They must be associated in one definite order; and theorder must once have been learned, i.e., it must have been picked out and held to more and moreexclusively out of the many other random orders which first presented themselves.The randomafferent impressions fell out, those that felt right were selected and grew together in the chain.Achain which we actively teach ourselves by stringing a lot of right-feeling impressions togetherdiffers in no essential respect from a chain which we passively learn from someone else whogives us impressions in a certain order.So to make our ideas more precise, let us take a particularconcatenated movement for an example, and let it be the recitation of the alphabet, whichsomeone in our childhood taught us to say by heart.What we have seen so far is how the idea of the sound or articulatory feeling of A may make ussay 'A,' that of B, 'B,' and so on.But what we now want to see is why the sensation that A isGet any book for free on: www.Abika.com THE PRINCIPLES OF PSYCHOLOGY382uttered should make us say 'B,' why the sensation that B is uttered should make us say 'C,' and soon.To understand this we must recall what happened when we first learned the letters in their order.Someone repeated A, B, C, D to us over and over again, and we imitated the sounds.Sensorycells corresponding to each letter were awakened in succession in such wise that each one ofthem (by virtue of our second law) must have 'drained' the cell just previously excited and left apath by which that cell tended even afterwards to discharge into the cell that drained it.Let Sa ,Sb, Sc in figure 89 stand for three of these cells.Each later one of them, as it discharges [p.588]motorwards, draws a current from the previous one, Sb from Sa, and Sc from Sb.Cell Sb havingthus drained Sa, if Sa ever gets excited again, it tends to discharge into Sb; whilst Sc havingdrained Sb, Sb later discharges into Sc, etc., etc.- all through the dotted lines.Let now the idea of the letter A arise in the mind, or, in other words, let Sa be aroused: whathappens? A current runs from Sa not only into the motor cell Ma for pronouncing that letter, butalso into the cell Sb
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