When a strong emotion is awakened in consciousness there are a large number of physiological reactions, for the most part visceral, which can be noted. Some of these may be graphically recorded and measured by means of instruments of precision. These physiological reactions are numerous and have been extensively described by Féré[[198]] among others. The earlier work of Mosso upon the disturbances of the respiration and vasomotor apparatus induced by sensory stimulation is well known.
More recently considerable experimental work has been done, particularly by German investigators, to determine the influence of affective states upon the circulation and respiration.
Modifications of the peripheral circulation, manifested through pallor or turgescence of the skin and measured by changes recorded by the plethismograph in the volume of the limbs; modifications of the volume of the heart and of the rhythm and force of the beats recorded by the sphygmograph, and of arterial tension measured by the sphygmomonometer are common phenomena. (Fear is more particularly accompanied by pallor, and shame by turgescence—blushing. Anger in some is manifested by pallor and in others by turgescence, and so on.) Changes in rate of the heart-beats belong to popular knowledge. It is not so well known, even to physiologists that the volume of the heart may be affected by emotion. In several series of observations made under conditions of emotional excitement upon a large number of healthy men, candidates for civil service appointments, I recorded in a high percentage not only alterations in the rate and rhythm and force of the heart-beat, but temporary dilatation of the heart lasting during the period of excitement.[[199]] This dilatation in some cases was sufficient to lead to insufficiency of the mitral valve and to give rise to murmurs. The examination was purposely conducted so as to induce a high degree of emotional excitement, at least in many men. In another series of observations (not published) the arterial tension was measured, and it was found, as would be expected, that an increase of tension accompanied the cardiac excitation under emotion.[[200]]
Fig. 2. J., acute katatonic stupor. b is a wave selected from the
series in which 6 is sudden call by name. The galvanometer curve (a)
is slight, but the change in the pneumograph curve is notable.
(Peterson and Jung.[[201]])
As to the respiratory apparatus the effect of emotion in altering the rate and depth of respiration may be shown by the pneumograph; by this method the effects of slight emotion that otherwise would escape observation may be detected. Such a disturbance of respiration is shown in the tracing, Fig. 2.
That emotion will profoundly affect the respiration has of course been common knowledge from time immemorial, and has been made use of by writers of fiction and actors for dramatic effect. The same may be said of modifications of the functioning of the whole respiratory apparatus, including the nostrils and the mouth; and likewise of the decrease or increase of secretions (dryness of the mouth from fear, and “foaming” from anger). These are among the well known physiological effects of emotions.
Increase of sweat sometimes amounting to an outpour, and alterations in the amount of the various glandular secretions (salivary, gastric, etc.), and rigor are important phenomena.
The remarkable researches of Pawlow[[202]] and his co-workers in Russia on the work of the digestive glands, and those of Cannon[[203]] in America on the movements of the stomach and intestines have revealed that these functions are influenced in an astonishing degree by psychical factors.
Although it has long been known that the sight of food under certain conditions would call forth a secretion of gastric juice in a hungry dog (Bidder and Smith, 1852), and common observation has told us that emotion strongly affects the gastrointestinal functions, increasing or diminishing the secretions of saliva and gastric juice, and even producing dyspeptic disturbances and diarrhœa, it has remained for Pawlow and his co-workers to demonstrate the important part which the “appetite,” as a psychical state, plays in the process of digestion. In hungry dogs a large quantity of gastric juice, rich in ferment, is poured out when food is swallowed, and even at the sight of food, and it was proved that this outpouring was due to psychical influences. Simply teasing and tempting the animal with food cause secretions, and food associations in the environment may have the same effect. “If the dog has not eaten for a long time every movement, the going out of the room, the appearance of the attendant who ordinarily feeds the animal—in a word, every triviality—may give rise to excitation of the gastric glands.” (Pawlow, p. 73.) This first secreted juice is called “appetite juice,” and is an important factor in the complicated process of digestion. “The appetite is the first and mightiest exciter of the secretory nerves of the stomach.” (Pawlow, p. 75.) Pawlow’s results have been confirmed in man by Hornborg, Umber, Bickel, and Cade and Latarjet. The mere chewing of appetizing food, for instance, is followed by a copious discharge of gastric juice, while chewing of rubber and distasteful substances has a negative result. Depressing emotions inhibit the secretion of juice (Bickel). More than this, Cannon,[[204]] in his very remarkable experiments on the movements of the stomach and intestines, found that in animals (cat, rabbit, dog, etc.), gastric peristalsis is stopped whenever the animal manifests signs of rage, distress, or even anxiety. “Any signs of emotional disturbance, even the restlessness and continual mewing which may be taken to indicate uneasiness and discomfort, were accompanied in the cat by total cessation of the segmentation movements of the small intestines, and of antiperistalsis in the proximal colon.” Bickel and Sasaki have confirmed in dogs these emotional effects obtained by Pawlow and Cannon.