My first interest in the conditions attending pain, hunger and strong emotional states was stimulated during the course of a previous series of researches on the motor activities of the alimentary canal. A summary of these researches appeared in 1911, under the title, “The Mechanical Factors of Digestion.” The studies recorded in the present volume may be regarded as a natural sequence of observations on the influence of emotional states on the digestive process, which were reported in that volume.
W. B. CANNON.
THE EFFECT OF THE EMOTIONS ON DIGESTION
Emotions favorable to normal secretion of the digestive juices—Emotions unfavorable to normal secretion of the digestive juices—Emotions favorable and unfavorable to contractions of the stomach and intestines—The disturbing effect of pain on digestion 1-21
THE GENERAL ORGANIZATION OF THE VIS-CERAt NERVES CONCERNED IN EMOTIONS
The outlying neurones—The three divisions of the outlying neurones—The extensive distribution of neurones of the “sympathetic” or thoracico-lumbar division and their arrangement for diffuse action—The arrangement of neurones of the cranial and sacral divisions for specific action—The cranial division a conserver of bodily resources—The sacral division a group of mechanisms for emptying—The sympathetic division antagonistic to both the cranial and the sacral—Neurones of the sympathetic division and adrenal secretion have the same action 22-39
METHODS OF DEMONSTRATING ADRENAL SECRETION AND ITS NERVOUS CONTROL
The evidence that splanchnic stimulation induces adrenal secretion—The question of adrenal secretion in emotional excitement—The method of securing blood from near the adrenal veins—The method of testing the blood for adrenin 40-51
ADRENAL SECRETION IN STRONG EMOTIONS AND PAIN
The evidence that adrenal secretion is increased in emotional excitement—The evidence that adrenal secretion is increased by “painful” stimulation—Confirmation of our results by other observers …. 52-65
THE INCREASE OF BLOOD SUGAR IN PAIN AND GREAT EMOTION
Glycosuria from pain—Emotional glycosuria—The role of the adrenal glands in emotional glycosuria . 66-80
IMPROVED CONTRACTION OF FATIGUED MUSCLE AFTER SPLANCHNIC STIMULATION OF THE ADRENAL GLAND
The nerve-muscle preparation—The splanchnic preparation—The effects of splanchnic stimulation on the contraction of fatigued muscle—The first rise in the muscle record—The prolonged rise in the muscle record—The two factors: arterial pressure and adrenal secretion 81-94
THE EFFECTS ON CONTRACTION OF FATIGUED MUSCLE OF VARYING THE ARTERIAL BLOOD PRESSURE
The effect of increasing arterial pressure—The effect of decreasing arterial pressure—An explanation of the effects of varying the arterial pressure—The value of increased arterial pressure in pain and strong emotion 95-109
THE SPECIFIC R6LE OF ADRENIN IN COUNTERACTING THE EFFECTS OF FATIGUE
Variations of the threshold stimulus as a measure of irritability—The method of determining the threshold stimulus—The lessening of neuro-muscular irritability by fatigue—The slow restoration of fatigued muscle to normal irritability by rest—The quick restoration of fatigued muscle to normal irritability by adrenin—The evidence that the restorative action of adrenin is specific—The point of action of adrenin in muscle 110-134
THE HASTENING OF THE COAGULATION OF BLOOD BY ADRENIN
The graphic method of measuring the coagulation time —The effects of subcutaneous injections of adrenin— The effects of intravenous injections—The hastening of coagulation by adrenin not a direct effect on the blood 135-160
THE HASTENING OF COAGULATION OF BLOOD IN PAIN AND GREAT EMOTION
Coagulation hastened by splanchnic stimulation—Coagulation not hastened by splanchnic stimulation if
the adrenal glands are absent—Coagulation hastened by “painful” stimulation—Coagulation hastened
in emotional excitement 161-183
THE UTILITY OF THE BODILY CHANGES IN PAIN AND GREAT EMOTION
The reflex nature of bodily responses in pain and the major emotions, and the useful character of reflexes—The utility of the increased blood sugar as a source of muscular energy—The utility of increased adrenin in the blood as an antidote to the effects of fatigue—The question whether adrenin normally secreted inhibits the use of sugar in the body—The vascular changes produced by adrenin favorable to supreme muscular exertion—The changes in respiratory function also favorable to great effort —The effects produced in asphyxia similar to those produced in pain and excitement—The utility of rapid coagulation in preventing loss of blood . 184-214
THE ENERGIZING INFLUENCE OF EMOTIONAL EXCITEMENT
“Reservoirs of power”—The excitements and energies of competitive sports—Frenzy and endurance in ceremonial and other dances—The fierce emotions and struggles of battle—The stimulating influence of witnesses and of music—The feeling of power . 215-231
CHAPTER XIII THE NATURE OF HUNGER
Appetite and hunger—The sensation of hunger—The theory that hunger is a general sensation—Weakness of the assumptions underlying the theory that hunger is a general sensation—Body need may exist without hunger—The theory that hunger is of gen-
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eral origin does not explain the quick onset and the periodicity of the sensation—The theory that hunger is of general origin does not explain the local reference—Hunger not due to emptiness of the stomach —Hunger not due to hydrochloric acid in the empty stomach—Hunger not due to turgescence of the gastric mucous membrane—Hunger the result of contractions—The “empty” stomach and intestines contract—Observations suggesting that contractions cause hunger—The concomitance of contractions and hunger in man 232-266
CHAPTER XIV THE INTERRELATIONS OF EMOTIONS
Antagonism between emotions expressed in the sympathetic and in the cranial divisions of the auto-nomic system—Antagonism between emotions expressed in the sympathetic and in the sacral divisions of the autonomic system—The function of hunger—The similarity of visceral effects in different strong emotions and suggestions as to its psychological significance 267-284
ALTERNATIVE SATISFACTIONS FOR THE FIGHTING EMOTIONS
Support for the militarist estimate of the strength of the fighting emotions and instincts—Growing opposition to the fighting emotions and instincts as displayed in war—The desirability of preserving the martial virtues—Moral substitutes for warfare—Physical substitutes for warfare—The significance of international athletic competitions 285-301
A LIST OF PUBLISHED RESEARCHES FROM THE PHYSIOLOGICAL LABORATORY IN HARVARD UNIVERSITY 302-303
BODILY CHANGES IN PAIN, HUNGER, FEAR AND RAGE
THE EFFECT OF THE EMOTIONS ON DIGESTION
The doctrine of human development from subhuman, antecedents has done much to unravel the complex nature of man. As a means of interpretation this doctrine has been directed chiefly toward the solving of puzzles in the peculiarities of anatomical structure. Thus arrangements in the human body, which are without obvious utility, receive rational explanation as being vestiges of parts useful in or characteristic of remote ancestors—parts retained in man because of agelong racial inheritance. This mode of interpretation has proved applicable also in accounting for functional peculiarities. Expressive actions and gestures—the facial appearance in anger, for example—observed in children and in widely distinct races, are found to be innate, and are best explained as the retention in human beings of responses which are similar in character in lower animals.
From this point of view biology has contributed much to clarify our ideas regarding the motives of human behavior. The social philosophies ^hich prevailed during the past century either assumed that conduct was determined by a calculated search for pleasure and avoidance of pain or they ascribed it to a vague and undefined faculty named the conscience or the moral sense. Comparative study of the behavior of men and of lower animals under various circumstances, however, especially with the purpose of learning the source of prevailing impulses, is revealing the inadequacy of the theories of the older psychologists. More and more it is appearing that in men of all races and in most of the higher animals, the springs of action are to be found in the influence of certain emotions which express themselves in characteristic instinctive acts.
The role which these fundamental responses in the higher organisms play in the bodily economy has received little attention. As a realm for investigation the bodily changes in emotional excitement have been left by the physiologists to the philosophers and psychologists and to the students of natural history. These students, however, have usually had too slight experience in the detailed examination of bodily functions to permit them to follow the clues which superficial observation might present. In consequence our
knowledge of emotional states has been meagre. There are, of course, many surface manifestations of excitement. The contraction of blood vessels with resulting pallor, the pouring out of “cold sweat,” the stopping of saliva-flow so that the “tongue cleaves to the roof of the mouth,” the dilation of the pupils, the rising of the hairs, the rapid beating of the heart, the hurried respiration, the trembling and twitching of the muscles, especially those about the lips—all these bodily changes are well recognized accompaniments of pain and great emotional disturbance, such as fear, horror and deep disgust. But these disturbances of the even routine of life, which have been commonly noted, are mainly superficial and therefore readily observable. Even the increased rapidity of the heart beat is noted at the surface in the pulsing of the arteries. There are, however, other organs, hidden deep in the body, which do not reveal so obviously as the structures near or in the skin, the disturbances of action which attend states of intense feeling. Special methods must be used to determine whether these deep-lying organs also are included in the complex of an emotional* agitation.
* In the use of the term “emotion” the meaning here is not restricted to violent affective states, but includes “feelings” and other affective experiences. At times, also, in order to avoid awkward expressions, the term is used in the popular manner, as if the “feeling” caused the bodily change.
Among the organs that are affected to an important degree by feelings are those concerned with digestion. And the relations of feelings to the activities of the alimentary canal are of particular interest, because recent investigations have shown that not only are the first stages of the digestive process normally started by the pleasurable taste and smell and sight of food, but also that pain and great emotional excitement can seriously interfere with the starting of the process or its continuation after it has been started. Thus there may be a conflict of feelings and of their bodily accompaniments—a conflict the interesting bearing of which we shall consider later.
EMOTIONS FAVORABLE TO NORMAL SECRETION OF THE DIGESTIVE JUICES
The feelings or affective states favorable to the digestive functions have been studied fruitfully by Pawlow, 1 of Petrograd, through ingenious experiments on dogs. By the use of careful surgical methods he was able to make a side pouch of a part of the stomach, the cavity of which was wholly separate from the main cavity in which the food was received. This pouch was supplied in a normal manner with nerves and blood vessels, and as it opened to the surface of the body, the amount and character of the gastric juice secreted by it under various conditions
could be accurately determined. Secretion by that part of the stomach wall which was included in the pouch was representative of the secretory activities* of the entire stomach. The arrangement was particularly advantageous in providing the gastric juice unmixed with food. In some of the animals thus operated upon an opening was also made in the esophagus so that when the food was swallowed, it did not pass to the stomach but dropped out on the way. All the pleasures of eating were thus experienced, and there was no necessity of stopping because of a sense of fulness. This process was called “sham feeding.” The well-being of these animals was carefully attended to, they lived the normal life of dogs, and in the course of months and years became the pets of the laboratory.
By means of sham feeding Pawlow showed that the chewing and swallowing of food which the dogs relished resulted, after a delay of about five minutes, in a flow of natural gastric juice from the side pouch of the stomach—a flow which persisted as long as the dog chewed and swallowed the food, and continued for some time after eating ceased. Evidently the presence of food in the stomach is not a prime condition for gastric secretion. And since the flow occurred only when the dogs had an appetite, and the material presented to them was agreeable, the conclusion
was justified that this was a true psychic secretion.
The mere sight or smell of a favorite food may start the pouring out of gastric juice, as was noted many years ago by Bidder and Schmidt 2 in a hungry dog which had a fistulous opening through the body wall into the stomach. This observation, reported in 1852, was confirmed later by Schiff and also still later by Pawlow. That the mouth “waters” with a flow of saliva when palatable food is seen or smelled has long been such common knowledge that the expression, “It makes my mouth water,” is at once recognized as the highest testimony to the attractiveness of an appetizing dish. That the stomach also “waters” in preparation for digesting the food which is to be taken is clearly proved by the above cited observations on the dog.
The importance of the initial psychic secretion of saliva for further digestion is indicated when, in estimating the function of taste for the pleasures of appetite, we realize that materials can be tasted only when dissolved in the mouth and thereby brought into relation with the taste organs. The saliva which “waters” the mouth assures the dissolving of dry but soluble food even when it is taken in large amount.
The importance of the initial psychic secretion of gastric juice is made clear by the fact that con-
tinuance of the flow of this juice during digestion is provided by the action of its acid or its digestive products on the mucous membrane of the pyloric end of the stomach, and that secretion of the pancreatic juice and bile are called forth by the action of this same acid on the mucous membrane of the duodenum. The proper starting of the digestive process, therefore, is conditioned by the satisfactions of the palate, and the consequent flow of the first digestive fluids. The facts brought out experimentally in studies on lower animals are doubtless true also of man. Not very infrequently, because of the accidental swallowing of corrosive substances, the esophagus is so injured that, when it heals, the sides grow together and the tube is closed. Under these circumstances an opening has to be made into the stomach through the side of the body and then the individual chews his food in the usual manner, but ejects it from his mouth into a tube which is passed through the gastric opening. The food thus goes from mouth to stomach through a tube outside the chest instead of inside the chest. As long ago as 1878, Eichet, 3 who had occasion to study a girl whose esophagus was closed and who was fed through a gastric fistula, reported that whenever the girl chewed or tasted a highly sapid substance, such as sugar or lemon juice, while the stomach was empty, there flowed
from the fistula a considerable quantity of gastric juice. A number of later observers 4 have had similar cases in human beings, especially in children, and have reported in detail results which correspond remarkably with those obtained in the laboratory. Hornborg 4 found that when the little boy whom he studied chewed agreeable food a more or less active secretion of gastric juice invariably started, whereas the chewing of an indifferent substance, as gutta-percha, was followed by no secretion. All these observations clearly demonstrate that the normal flow of the first digestive fluids, the saliva and the gastric juice, is favored by the pleasurable feelings which accompany the taste and smell of food during mastication, or which are roused in anticipation of eating when choice morsels are seen or smelled.
These facts are of fundamental importance in the serving of food, especially when, through illness, the appetite is fickle. The degree of daintiness with which nourishment is served, the little attentions to esthetic details—the arrangement of the dishes, the small portions of food, the flower beside the plate—all may holp to render food pleasing to the eye and savory to the nostrils and may be the deciding factors in determining whether the restoration of strength is to begin or not.
EMOTIONS UNFAVORABLE TO THE NORMAL SECRETION OF THE DIGESTIVE JUICES
\The conditions favorable to proper digestion are wholly abolished when unpleasant feelings such as vexation and worry and anxiety, or great emotions such as anger and fear, are allowed to prevail. This fact, so far as the salivary secretion is concerned, has long been known. The dry mouth of the anxious person called upon to speak in public is a common instance; and the “ordeal of rice,” as employed in India, was a practical utilization of the knowledge that excitement is capable of inhibiting the salivary flow. When several persons were suspected of crime, the consecrated rice was given to them all to chew, and after a short time it was spit out upon the leaf of the sacred fig tree. If anyone ejected it dry, that was taken as proof that fear of being discovered had stopped the secretion, and consequently he was adjudged guilty. 5
What has long been recognized as true of the secretion of saliva has been proved true also of the secretion of gastric juice. For example, Ilornborg was unable to confirm in his little patient with a gastric fistula the observation by Pawlow that when hunger is present the mere seeing of food results in a flow of gastric juice. Ilornborg explained the difference between his and Pawlow’s results by the different ways in
which the boy and the dogs faced the situation. When food was shown, but withheld, the hungry dogs were all eagerness to secure it, and the juice very soon began to flow. The boy, on the contrary, became vexed when he could not eat at once, and began to cry; then no secretion appeared. Bogen also has reported the instance of a child with closed esophagus and gastric fistula, who sometimes fell into such a passion in consequence of vain hoping for food that the giving of the food, after the child was calmed, was not followed by any flow of the secretion.
The inhibitory influence of excitement has also been seen in lower animals under laboratory conditions. Le Conte 6 declares that in studying gastric secretion it is necessary to avoid all circumstances likely to provoke emotional reactions. In the fear which dogs manifest when first brought into strange surroundings he found that activity of the gastric glands may be completely suppressed. The suppression occurred even if the dog had eaten freely and was then disturbed —as, for example, by being tied to a table. When the animals became accustomed to the experimental procedure, it no longer had an inhibitory effect. The studies of Bickel and Sasaki 7 confirm and define more precisely this inhibitory effect of strong emotion on gastric secretion. They observed the inhibition on a dog with an