1921] on The Electrical Expression of Human Emotion 285 



disturbing effect of any real interference with his comfort. The 

 emotive effects of my threatening language must be allowed to 

 subside. You cannot expect to study rings made by throwing a stone 

 into a pond unless the pond is quiet ; you must wait for it to get 

 still. When he comes to rest Mr. X. Y. will react smartly and 

 obviously in response to the suddenly threatened pin-prick or to a 

 real pin-prick. [Trials by pin and matches. Real and imaginary 

 pin-pricks and burns.] 



You now, perhaps, feel fairly well satisfied that a statement made 

 a few minutes ago is correct. In the upper limb of a normal person 

 emotive responses to slight excitations are confined to the palm of 

 the hand. The only other part of the body in which they occur is 

 the sole of the foot, but this I shall ask you to take on trust ; it 

 really is not necessary that the actual evidence should be brought 

 into court, ^t would merely be a repetition of what you have just 

 witnessed ; and this lantern-plate (Fig. 1) will, after all, afford us 

 the quickest, as well as the most conclusive, evidence. 



5. I shall venture to trespass just a little further upon Mr. X. Y.'s 

 endurance to make good one further point, although it is a point 

 that you may already have noticed. 



This palmar emotive response is, in my view, to be regarded as 

 caused by a sudden augmentation of electrical conductivity in a 

 membrane or membranes in the fourth arm of the Wheatstone square. 

 That augmentation of conductivity is to be understood as produced 

 by a sudden dilatation of ultramicroscopic pores in this membrane or 

 membranes. I am not speaking of visible pores, but of invisible pores 

 such as are postulated in theories of electrical conduction and of 

 osmotic phenomena. I imagine that these invisible pores suddenly 

 dilate when the emotive impulse through efferent nerves reaches the 

 living membrane, just as we see the pupil of the eye dilate with an 

 emotion of surprise. And with this image in my mind I find it 

 extremely interesting to recognise and measure what a very long- 

 time it takes for any given stimulus tc produce its effect. It takes 

 two seconds before the threat of a pin-prick — or, for the matter of 

 that, an actual pin-prick — or a single induction shock, brings about 

 the sudden dilatation of pores or increased permeability and the 

 increased electrical conductivity that are signified to us by the 

 movement of the spot of light. How is this long lag of two seconds 

 to be accounted for ? Does it occur on the afferent side ? Assuredly 

 not. A delay of this sort might be expected to amount to at most 

 one-fifth of a second. Moreover, if we miss out the afferent side 

 altogether, and bring about the response by an artificial explosion 

 down efferent nerves, we shall find the same long delay of two 

 seconds between the muscular movement and the emotive movement, 

 both of which are taking place at the periphery. Therefore, the 

 chief business of the long delay takes place at the periphery, in the 

 skin of the palm of the hand, and its great length is a token that 



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