Most of the viscera are innervated by the sympathetic system, and the visceral manifestations of emotion indicate the dominance of sympathetic impulses. “When, for example, a cat becomes frightened, the pupils dilate, the stomach and intestines are inhibited, the heart beats rapidly, the hairs of the back and tail stand erect—all signs of nervous discharge along sympathetic paths” (Cannon). Cannon and his co-workers have further made the acute suggestion that, as adrenalin itself is capable of working the effects evoked by sympathetic stimulation, “the persistence of the emotional state, after the exciting object has disappeared, can be explained” by the persistence of the adrenalin in the blood. There is reason to believe that some of the adrenal secretion set free by nervous stimulation returning in the blood stream to the glands stimulates them to further activity, and this would tend to continue the emotional effect after the emotion has subsided. “Indeed it was the lasting effect of excitement in digestive processes which suggested” to Cannon his investigations.[[208]]
According to Féré[[209]] the pupils may dilate under the influence of asthenic emotions and contract with sthenic emotions. However that may be, the dilatation of the pupils during states of fear may be demonstrated in animals.
exert force of which he is ordinarily incapable. Or this energy, instead of being discharged into the channels being made use of by the will, and so augmenting its effects, may be so discharged as to inhibit the will, and produce paralysis of the will and muscular action.
These muscular vasomotor and secretory changes need not surprise us, as indeed they have a biological meaning. As Sherrington[[210]] has pointed out, “there is a strong bond between emotion and muscular action. Emotion ‘moves’ us, hence the word itself. If developed in intensity, it impels toward vigorous movement. Every vigorous movement of the body ... involves also the less noticeable co-operation of the viscera, especially of the circulatory and respiratory [and, I would add, the secretory glands of the skin]. The extra demand made upon the muscles that move the frame involves a heightened action of the nutrient organs which supply to the muscles the material for their energy”; and also involves a heightened action of the sweat glands to maintain the thermic equilibrium. “We should expect,” Sherrington remarks, “visceral action to occur along with the muscular expression of emotion,” and we should expect, it may be added, that through this mechanism emotion should become integrated with vasomotor, secretory, and other visceral functions.
Another physiological effect of emotion ought to be mentioned, as of recent years it has been the object of much and intensive study by numerous students and has been frequently made use of in the clinical study of mental derangements and in the study of subconscious phenomena. I refer to the so-called “psycho-galvanic reflex.” As an outcome of all the investigations which have been made by numerous students into this phenomenon, it now seems clear that there are two types of galvanic reactions, distinct from each other, which can be recognized. The one type first described by Féré[[211]] consists in an increase, brought about by emotion, of a galvanic current made to pass through the body from a galvanic cell. If a very sensitive galvanometer is put in circuit with the body and such a cell, a certain deviation of the needle of course may be noted varying in amplitude according to the resistance of the body. Now, if an idea associated with emotion—i.e., possessing a sufficient amount of affective tone—is made to enter the consciousness of the person experimented upon, there is observed an increased deflection of the needle, showing an increase of current under the influence of the emotion. The generally accepted interpretation of this increase is that it is due to diminished resistance of the skin (with which the electrodes are in contact) caused by an increase of the secretions of the sweat glands. A similar increase of current follows various sensory stimulations, such as the pricking of a pin, loud noises, etc. It may be interesting for historical reasons to quote here Féré’s statement of his observations, as they seem to be generally overlooked. In his volume, “La Pathologie des Emotions,” in 1892, he thus sums up his earlier and later observations: "I then produce various sensory stimulations—visual (colored glasses), auditory (tuning fork), gustatory, olfactory, etc. Whereupon there results a sudden deviation of the needle of the galvanometer which, for the strongest stimulations, may travel fifteen divisions (milliampères). The same deviation may also be produced under the influence of sthenic emotions, that is to say, it is produced under all the conditions where I have previously noticed an augmentation of the size of the limbs, made evident through the plethysmograph. Absence of stimulation, on the contrary, increases the resistance; in one subject the deviation was reduced by simply closing the eyes.
“Since these facts were first described at the Biological Society I have been enabled to make more exact observations by using the process recommended by A. Vigouroux (De la résistance électrique chez[chez] les mélancoliques, Th. 1890, p. 17), and I have ascertained that under the influence of painful emotions or tonic emotions the electrical resistance may, in hystericals, instantaneously vary from 4,000 to 60,000 ohms.”
It will be noticed that Féré attributed the variations of the current to variations of resistance of the body induced by sensations and emotions.
The method of obtaining the psycho-galvanic reaction may be varied in many ways, the underlying principle being the same, namely, the arousing of an emotion of some kind. This may be simply through imagined ideas, or by expectant attention, sensory stimulation, suggested thoughts, verbal stimuli, etc. According to Peterson and Jung,[[212]] “excluding the effect of attention, we find that every stimulus accompanied by an emotion causes a rise in the electric curve, and directly in proportion to the liveliness and actuality of the emotion aroused. The galvanometer is therefore a measurer of the amount of emotional tone, and becomes a new instrument of precision in psychological research.” This last statement can hardly be said to be justified, as we have no means of measuring the “liveliness and actuality” of an emotion and, therefore, of co-relating it with a galvanic current, nor have we any grounds for assuming that the secretion of sweat (upon which the diminished resistance of the body presumably depends) is proportionate to the liveliness of the emotion, or, indeed, even that it always occurs. It is enough to say that the galvanic current is in general a means of detecting the presence of emotion.
The second type of galvanic reaction, as shown by Sidis and Kalmus,[[213]] does not depend upon the diminished resistance of the body to a galvanic current passing from without through the body, but is a current originating within the body under the influence of emotion. Sidis and Kalmus concluded that “active psycho-physiological processes, sensory and emotional processes, with the exception of purely ideational ones, initiated in a living organism, bring about electromotive forces with consequent galvanometric deflections.” In a later series of experiments Sidis and Nelson[[214]] came to the conclusion that the origin of the electromotive force causing the galvanic deflection was in the muscles.[[215]] Wells and Forbes,[[216]] on the other hand, conclude from their own investigation that the origin of the galvanic current is to be found in the sweat gland activity and believe the muscular origin improbable. From a clinical standpoint the question is unimportant.
Sensory disturbances. On the sensory side the effect of emotions, particularly unpleasant ones, in awakening “thrills” and all sorts of sensations in different parts of the body is a matter of everyday observation. Nausea, dizziness, headache, pains of different kinds are common accompaniments. Such reactions, however, largely vary as idiosyncrasies of the individual, and are obviously not open to experimentation or measurement. Whether they should be spoken of as physiological or aberrant reactions is a matter of terminology. They are, however, of common occurrence. In pathological conditions disagreeable sensations accompanying fear, grief, disgust, and other distressing forms of emotion often play a prominent part, and as symptoms contribute to the syndromes of the psychosis. The following quaintly described case quoted by Cannon from Burton’s Anatomy of Melancholy is as good as a more modern illustration: “A gentlewoman of the same city saw a fat hog cut up; when the entrails were opened, and a noisome savour offended her nose, she much disliked, and would not longer abide; a physician in presence told her, as that hog, so was she full of filthy excrements, and aggravated the matter by some other loathsome instances, insomuch this nice gentlewoman apprehended it so deeply that she fell forthwith a vomiting; was so mightily distempered in mind and body that, with all his art and persuasion, for some months after, he could not restore her to herself again; she could not forget or remove the object out of her sight.” Cannon remarks: “Truly, here was a moving circle of causation, in which the physician himself probably played the part of a recurrent augmenter of the trouble. The first disgust disturbed the stomach, and the disturbance of the stomach, in turn, aroused in the mind greater disgust, and thus between them the influences continued to and fro until digestion was impaired and serious functional derangement supervened. The stomach is ‘king of the belly,’ quotes Burton, ‘for if he is affected all the rest suffer with him.’”