The Origin and Nature of the Emotions; Miscellaneous Papers

by George Washington Crile

{illust. caption = FIG. 25.—FEAR AND AGONY. "Amid this dread exuberance of woe ran naked spirits wing'd with horrid fear."— Dante's "Inferno," Canto XXIV, lines 89, 90. all the stimuli reached the brain-cells simultaneously, the cells would find themselves in equilibrium and no motor act would be performed. But if all the pain receptors of the body but one were equally stimulated, and this one stimu-lated harder than the rest, then the latter would gain possession of the final common path, the sensation of pain would be felt, and a muscular contraction would result. It is well known that when a greater pain is thrown into competition with a lesser one, the lesser is completely submerged. In this manner the school-boy initiates the novice into the mystery of the painless plucking of hair. The simultaneous, but severe application of the boot to the blindfolded victim takes complete and exclusive possession of the final common path and the hair is painlessly plucked through the triumph of the boot stimulus over the hair stimulus in the struggle for the possession of the final common path. Another argument in favor of this hypothesis that pain is an accompaniment of the release of energy in the brain- cells is found in the fact that painless stimuli received through the special senses may completely submerge the painful stimuli of physical injury; for although the stimuli to motor action, which are received through the senses of sight, hearing, and smell, cause even more powerful motor action than those caused by physical contact stimuli, yet they are not accompanied by pain. Examples of this triumph of stimulation of the special senses over contact stimulation are frequently seen in persons obsessed by anger or fear, and to a less degree in those obsessed by sexual emotion. In the fury of battle the soldier may not perceive his wound until the emotional excitation is wearing away, when the sensation of warm blood on the skin may first attract his attention. Religious fanatics are said to feel no pain when they subject themselves to self-injury. Now, since both psychic and mechanical stimuli cause motor action by the excitation ofprecisely the same mechanism in the brain, and since the more rapid release of energy from psychic stimuli submerges the physical stimuli and prevents pain, it would seem that pain must be a phenomenon which is associated with the process of releasing energy by the brain-cells. Were physical injury inflicted in a quiescent state equal to that inflicted in the emotional state, great pain and intense muscular action would be experienced. Now the emotions are as purely motor excitants as is pain. The dynamic result is the same the principal difference being the greater suddenness and the absolute specificity of the pain stimuli as compared with the more complex and less peremptory stimuli of the emotions. A further evidence that pain is a product of the release of brain-cell energy is the probability that if one could pierce the skin at many points on a limb in such a manner that antagonistic points only were equally and simultaneously stimulated, then an equilibrium in the governing brain- cells would be established and neither pain nor motion would follow. An absolute test of this assumption cannot be made but it is supported by the obtainable evidence. We will now turn to a new viewpoint, a practical as well as a fascinating one, which can best be illustrated by two case histories: A man, seventy-eight years old, whose chief complaint was obstinate constipation, was admitted to the medical ward of the Lakeside Hospital several years ago. The abdomen was but slightly distended; there was no fever, no increased leukocytosis, no muscular rigidity, and but slight general tenderness. He claimed to have lost in weight and strength during the several months previous to his admission. A tentative diagnosis of malignant tumor of the large intestine was made, but free movements weresecured rather easily, and we abandoned the idea of an exploratory operation. The patient gradually failed and died without a definite diagnosis having been made by either the medical or the surgical service. At autopsy there was found a wide-spread peritonitis arising from a perforated appendix. A child, several years old, was taken ill with some indefinite disease. A number of the ablest medical and surgical consultants of a leading medical center thoroughly and repeatedly investigated the case. Although they could make no definite diagnosis they all agreed that the trouble surely could not be appendicitis because there was neither muscular rigidity nor tenderness. The autopsy showed a gangrenous appendix and general peritonitis. How can these apparently anomalous cases be explained? These two cases are illustrations of the same principle that underlies the freedom from pain which results from the use of narcotics and anesthetics, the same principle that explains the fact that cholecystitis may occur in the aged without any other local symptoms than the presence of a mass and perhaps very slight tenderness; and that accounts in general for the lack of well-expressed disease phenomena in senility and in infancy. The reason why the aged, the very young, and the subjects of general paresis show but few symptoms of disease is that in senility the brain is deteriorated, while in infancy the brain is so undeveloped that the mechanism of association is inactive, hence pain and tenderness, which are among the oldest of the associations, are wanting. Senility and infancy are by nature normally narcotized. The senile are passing through the twilight into the night; while infants are traversing through the dawn into the day. Hence it is that the diagnosis of injury and disease in the extremes oflife is beset by especial difficulties, since the entire body is as silent as are the brain, the pericardium, the mediastinum, and other symptomless areas. For the same reason, when a patient who is seriously ill with a painful disease turns upon the physician a glowing eye and an eager face, and remarks how comfortable he feels, then the end is near. This is a brilliant and fateful clinical mirage. When one reflects on the vast amount of evidence as to the origin and the purpose of pain, he is forced to conclude that pain is a phenomenon of motor stimulation, and that its principal role is the protection of the individual against the gross and the microscopic enemies in his environment. The benefits of pain are especially manifested in the urgent muscular actions by means of which the body moves away from physical injury; obstructions of the hollow viscera are overcome; rest is compelled in the acute infections— the infected points are held rigidly quiet, the muscles of the abdomen are fixed, and harmful peristalsis is arrested in peritonitis; while there is absolutely no pain in the diseases or injuries which affect those regions of the body in which in the course of evolution no pain receptors were placed, or in those diseases in which muscular inhibition or contraction is of no help. In a biologic sense pain is closely associated with the emotional stimuli, for both pain and the emotions incite motor activity for the good of the individual. The frequent occurrence of post-operative and post- traumatic pain is accounted for by the fact that the operation or the injury has lowered the threshold of the brain- cells to trauma; the brain and not the local sensitive field is the site of the pain. I have found that, by blockingthe field of operation with local anesthesia, post-operative pain is diminished; that is, since the local anesthesia prevents the strong stimuli of the trauma from reaching the brain, its threshold is not lowered. There is a close resemblance between the phenomena of pain habit, of education, of physical training, of love and of hate. In education, in pain habit, in all emotional relations, a low brain- cell threshold is established which facilitates the reception of specific stimuli; all these processes are motor acts, or are symbolic of motor acts, and we may be trained to perceive misfortune and pain as readily as we are trained to perceive mathematical formulae or moral precepts. In each and every case, readiness of perception depends, as it seems to me, upon a modified state of the brain-cells, their threshold especially, the final degree of perception possible in any individual being perhaps based on the type of potential molecules of which the brain is built. We must believe also that every impression is permanent, as only thus could an individual animal or a man be fitted by his own experience for life's battles. LAUGHTER AND CRYING What is laughter? What is its probable origin, its distribution, and its purpose? Laughter is an involuntary rhythmic contraction of certain respiratory muscles, usually accompanied by certain vocal sounds. It is a motor act of the respiratory apparatus primarily, although if intense it may involve not only the extraordinary muscles of respiration, but most of the muscles of the body. There are many degrees of laughter, from the mere brightening of the eyes, a fleeting smile, tittering andgiggling, to hysteric and convulsive laughter. Under certain circumstances, laughter may be so intense and so long continued that it leads to considerable exhaustion. The formation of tears is sometimes associated with laughter. When integrated with laughter, the nervous system can perform no other function. Crying is closely associated with laughter, and in children especially laughter and crying are readily interchanged. We postulate that laughter and weeping serve a useful purpose. According to Darwin, only man and monkeys laugh (Fig. 26); other animals exhibit certain types of facial expression accompanying various emotions, but laughter in the sense in which that word is commonly used is probably an attribute of the primates only, although it is probable that many animals find substitutes for laughter. The proneness of man to laughter is modified by age, sex, training, mental state, health, and by many other factors. Healthy, happy children are especially prone to laughter, while disease, strong emotions, fatigue, and age diminish laughter. Women laugh more than do men. The healthy, happy maturing young woman perhaps laughs most, especially when she is slightly embarrassed. What causes laughter? Good news, high spirits, tickling, hearing and seeing others laugh; droll stories; flashes of wit; passages of humor; averted injury; threatened breach of the conventions; and numerous other causes might be added. It is obvious that laughter may be produced by diverse influences, many of which are so unlike each other that it would at first sight seem improbable that a single general principle underlies all. Before presenting a hypothesis which harmonizes most of the facts, and which mayoffer an explanation of the origin and purpose of laughter, let us return for a moment to some previous considerations— that man is essentially a motor being; that all his responses to the physical forces of his environment are motor; {illust. caption = FIG. 26.—LAUGHING CHIMPANZEE. "Mike," the clever chimpanzee in the London Zoo, evidently enjoys a joke as well as any one else. (Photo by Underwood and Underwood, N. Y.)}

that thoughts and words even are symbolic of motor acts; that in the emotions of fear, of anger, and of sexual love the whole body is integrated for acts which are not performed. These integrations stimulate the brain-cells, the ductless glands, and other parts, and the energizing secretions, among which are epinephrin, thyroid and hypophyseal secretions, are thrown into the blood-stream, while that most available fuel, glycogen, is also mobilized in the blood. This body-wide preparation for action may be designated kinetic reaction. The fact that emotion is more injurious to the body than is muscular action is well known, the difference being probably caused by the fact that when there is action the above-mentioned products of stimulation are consumed, while in stimulation without action they are not consumed and must be eliminated as waste products. Now these activating substances and the fuel glycogen may be consumed by any muscular action as well as by the particular muscular action for which the integration and consequent stimulation were made; that is, if one were provoked to such anger that he felt impelled to attack the object of his anger, one of three things might happen: First, he might perform no physical act but give expression to the emotion of anger; second, he might engage in a physical struggle and completely satisfy his anger; third, he might immediately engage in violent gymnastic exercises and thus consume all the motor-producing elements mobilized by the anger and thus clarify his body.

In these premises we find our explanation of the origin and purpose of laughter and crying, for since they consist almost wholly of muscular exertion, they serve precisely such clarifying purposes as would be served by the gymnastic exercises of an angry man. As it seems to me, the muscular action of laughter clears the system of the energizing substances which have been mobilized in various parts of the body for the performance of other actions (Figs. 27 to 29). If this be true, the first question that presents itself is, Why is the respiratory system utilized for such a clarifying purpose? Why do we not laugh with our feet and hands as well? Were laughter expressed with the hands, the monkey might fall from the tree and, if by the feet, man might fall to the ground. He would at least be ataxic. In fact, laughter has the great advantage of utilizing a group of powerful muscles which can be readily spared without seriously interfering with the maintenance of posture. Laughter, however, is only one form of muscular action which may consume the fuel thrown into the blood by excitation. That these products of excitation are often consumed by other motor acts than laughter is frequently seen in public meetings when the stamping of feet and the clapping of hands in applause gives relief to the excitation (Fig. 30). Why the noise of laughter? In order that the products of excitation may be quickly and completely consumed, the powerful group of expiratory muscles must have some resistance against which they can exert themselves strongly and at the same time provide for adequate respiratory exchange. The intermittent closure of the epiglottis serves this purpose admirably, just as the horizontal bars afford the resistance against which muscles may be exercised. The facial muscles are not in use for other purposes, hence their contractions will consume a little of the fuel. An audience excited by the words of an impassioned speaker undergoes a body-wide stimulation for action, all of which may be eliminated by laughter or by applause (Fig. 31).

Let us test this hypothesis by some practical examples. The first is an incident that accidentally occurred in our laboratory during experiments on fear which were performed as follows: A keen, snappy fox terrier was completely muzzled by winding a broad strip of adhesive plaster around his jaw so as to include all but the nostrils. When this aggressive little terrier and the rabbit found themselves in close quarters each animal became completely governed by instinct; the rabbit crouched in fear, while the terrier, with all the ancestral assurance of seizing his prey, rushed, upon the rabbit, his muzzle always glancing off and his attack ending in awkward failure.

This experiment was repeated many times and each time provoked the serious-minded scientific visitors who witnessed it to laughter. Why? Because the spectacle of a savage little terrier rushing upon an innocent rabbit as if to mangle it integrated the body of the onlooker with a strong desire to exert muscular action to prevent the cruelty. This integration caused a conversion of the potential energy in the brain-cells into kinetic energy, and there resulted a discharge into the blood-stream of activating internal secretions for the purpose of producing muscular action. Instantly and unexpectedly the danger passed and the preparation for muscular action intended for use in the protection of the rabbit was not needed. This fuel was consumed by the neutral muscular action of laughter, which thus afforded relief.

A common example of the same nature is that encountered on the street when a pedestrian slips on a banana peel and, just as he is about to tumble, recovers his equilibrium. The onlookers secure relief from the integration to run to his rescue by laughing. On the other hand, should the same pedestrian fall and fracture his skull the motor integration of the onlookers would be consumed by rendering physical assistance—hence there would be no laughter. In children almost any unexpected phenomenon, such as a sudden "booing" from behind a door, is attended by laughter, and in like manner the kinetic reaction produced by the innumerable threats of danger which are suddenly averted, a breach of the conventions, a sudden relief from acute nervous tension; a surprise—indeed, any excitant to which there is no predetermined method of giving a physical response— may be neutralized by the excitation of the mechanism of laughter.

In the same way the laughter excited by jokes may be explained. An analysis of a joke shows that it is composed of two parts— the first, in which is presented a subject that acts as a stimulus to action, and the second, in which the story turns suddenly so that the stimulus to action is unexpectedly withdrawn. The subject matter of the joke affects each hearer according to the type of stimuli that commonly excites that individual. Hence it is that a joke may convulse one person while it bores another, and so there are jokes of the classes, bankers' jokes, politicians' jokes, the jokes of professional men, of the plebeian, of the artist, etc. If the joke fails, the integration products of the excitation may be used in physical resentment (Fig. 32).

Another type of laughter is that associated with the ticklish points of certain parts of the body, the soles of the feet and certain parts of the trunk and of the abdomen. The excitation of the ticklish receptors, like pain, compels self-defensive motor acts. This response is of phylogenetic origin, and may be awakened only by stimuli which are too light to be painful. In this connection it is of interest to note that a superficial, insect-like contact with the skin rarely provokes laughter, and that the tickling of the nasal, oral, and pulmonary tracts does not produce laughter. The ticklish points that cause laughter are rather deeply placed, and a certain type of physical contact is required to constitute an adequate stimulus. That is, the contact must arouse a phylogenetic association with a physical struggle or with physical exertion. In the foot, the adequate stimuli for laughter are such contacts as resemble or suggest piercing by stones or rough objects.. The intention of the one who tickles must be known; if his intention be playful, laughter results, whereas if injury be intended, then an effort toward escape or defense is excited, but no laughter. If deep tickling of the ribs is known to be malicious, it will excite physical resentment and not laughter. Self-tickling rarely causes laughter for the reason that auto-tickling can cause only a known degree of stimulation, so that there results no excessive integration which requires relief by the neutral muscular activity of laughter. In fact, one never sees purposeful acts and laughter associated. According to its severity, an isolated stimulus causes either an action or laughter. The ticklish points in our bodies were probably developed as a means of defense against serious attacks and of escape from injurious contacts.

Anger, fear, and grief are also strong excitants and, therefore, are stimuli to motor activity. It is obvious that whatever the excitant the physico-chemical action of the brain and the ductless glands cannot be reversed—the effect of the stimulus cannot be recalled, therefore either a purposeful muscular act or a neutralizing act must be performed or else the liberated energy must smoulder in the various parts of the body.

It is on this hypothesis that the origin and the purpose of laughter and crying may be understood. Even a superficial analysis of the phenomena of both laughter and crying show them to be without any external motor purpose; the respiratory mechanism is intermittently stimulated and inhibited; and the shoulder and arm muscles, indeed, many muscles of the trunk and the extremities are, as far as any external design is concerned, purposelessly contracted and released until the kinetic energy mobilized by excitation is utilized. During this time the facial expression gives the index to the mental state.