THE EXPRESSION OF THE FOREHEAD AND EYE

I

Those who have not carefully followed the history of scientific progress think that the theory of evolution is solely Darwin’s work. The same thing has happened as after a victory, when public opinion lauds the name of a single general, whereas the action of others was no less efficacious and decisive in winning the battle. But in this case it would be an injustice not to award the greatest praise to Herbert Spencer, whom Darwin himself called 'the great expounder’ of the principle of evolution. So soon as 1855, in the first edition of his 'Principles of Psychology,’ Spencer maintains the doctrine of evolution, when, as he says, it was 'ridiculed in the world at large and frowned upon in the scientific world.’

In the second edition of his 'Principles of Psychology,’ Spencer added a chapter entitled, 'The Language of the Emotions,’ which is of great value to us, as it was printed a few months before Darwin published his book, 'The Expression of the Emotions.’

One of the most important ideas, physiologically speaking, which Spencer has formulated is the following: 'The molecular motion disengaged in any nerve-centre by any stimulus, tends ever to flow along lines of least resistance throughout the nervous system, exciting other nerve-centres, and setting up other discharges. The feelings of all orders, moderate as well as strong, which from instant to instant arise in consciousness, are the correlatives of nerve-waves continually being generated and continually reverberating throughout the nervous system—the perpetual nervous discharge constituted by these perpetually-generated waves, affecting both the viscera and the muscles, voluntary and involuntary.’

The ideas developed by Darwin on the origin of the expressions have such a striking resemblance, even identity, with Spencer’s doctrine, that Darwin felt himself obliged to make the following declaration in a foot-note: 'I may state, in order that I may not be accused of trespassing on Mr. Spencer’s domain, that I announced in my “Descent of Man” that I had then written a part of the present volume.’[21]

The origin of the movements of expression, as propounded by Spencer and more amply developed by Darwin in his book, does not convince me. The profound admiration which I cherish for these two great masters has made me timid in deviating from their path, but since the facts which presented themselves to me during my studies have convinced me that the same results might be obtained in another way, it is my duty to communicate those observations and experiments which point to another solution of the problem.

I shall here quote a passage from Spencer’s 'Language of the Emotions,’ thus drawing, as we say, from the well of the great philosopher himself.

'Throughout the animal kingdom, non-pleasurable feelings are most frequently and most variously excited during antagonism. Among inferior types of creatures antagonism habitually implies combat, with all its struggles and pains. Though in man there are many sources of non-pleasurable feelings other than antagonism, and though antagonism itself ends in combat only when it rises to an extreme, yet as among inferior ancestral types antagonism is the commonest and most conspicuous accompaniment of non-pleasurable feeling, and continues to be very generally an accompaniment in the human race, there is organically established a relation between non-pleasurable feeling and the muscular actions which antagonism habitually causes. Hence those external concomitants of non-pleasurable feeling which constitute what we call its expression, result from incipient muscular contractions of the kinds accompanying actual combat.

'But how does this explain the first and most general mark of non-pleasurable feeling—a frown? What have antagonism and combat to do with that corrugation of the brow which, when slight, may indicate a trifling ache or a small vexation, and when decided, may have for its cause bodily agony, or extreme grief, or violent anger? The reply is not obvious, and yet, when found, is satisfactory.

'If you want to see a distant object in bright sunshine, you are aided by putting your hand above your eyes; and in the tropics, this shading of the eyes to gain distinctness of vision is far more needful than here. In the absence of shade yielded by the hand or by a hat, the effort to see clearly in broad sunshine is always accompanied by a contraction of those muscles of the forehead which cause the eyebrows to be lowered and protruded; so making them serve as much as possible the same purpose that the hand serves.... Now if we bear in mind that during the combats of superior animals, which have various movements of attack and defence, success largely depends on quickness and clearness of vision ... it will be manifest that a slight improvement of vision, obtained by keeping the sun’s rays out of the eyes, may often be of great importance, and where the combatants are nearly equal, may determine the victory.... Hence, we may infer that during the evolution of those types from which man more immediately inherits, it must have happened that individuals in whom the nervous discharge accompanying the excitement of combat, caused an unusual contraction of these corrugating muscles of the forehead, would, other things equal, be the more likely to conquer and to leave posterity—survival of the fittest tending in their posterity to establish and increase this peculiarity.’

If this interpretation of Spencer, which Darwin expanded, were true, the consequences would be, that in the long succession of generations animals would have gradually rid themselves of that which is injurious and fatal to them. But this law does not verify itself in the least, rather do we see, in studying violent emotions, that the more serious the danger the greater is the predominance both in number and strength of injurious phenomena. We have already seen that trembling and cataplexy render us unable to flee or defend ourselves, and we shall now be convinced that in critical moments we see less distinctly than when we are tranquil.

In the face of these facts we must admit that not all phenomena of fear can be explained by the theory of selection. In their extreme degrees they are morbid phenomena indicating an imperfection of the organism. One might almost say that nature had not been able to find a substance for brain and spinal cord which should be extremely sensitive, and yet should never, under the influence of exceptionally strong stimuli, exceed in its reaction those physiological limits which are best adapted to the preservation of the animal.

But before we go further, let us consider those facts which seem to contradict the hypothesis of Spencer and Darwin.

II

We all know that the pupil through which the rays of light pass, in order to reach the posterior part of the eye, dilates and contracts with great facility. In the cat its form is variable; generally elliptic, it becomes in a strong light very narrow and nearly shut, appearing like a slit scarcely wider than a hair; towards evening, or in a dark place during the day, it dilates in such a manner that the iris nearly disappears, and one can see the greenish, phosphorescent background of the eye.

The iris is like a circular curtain which closes in a strong light and opens in the dark, regulating automatically the amount of light necessary for sight without causing injury to the eye.

The perfection of our machine is such, that some indispensable mechanisms not only work automatically, without any participation of the will or consciousness, but often also without needing either spinal cord or brain, as those few nerve-cells, found in the organs in the form of microscopic ganglia, suffice for the reflex movements. This harmony by which the body assures the performance of its most important functions, by putting in motion several mechanisms at the same time, all of which are directed to the same end, is worthy of meditation.

The mechanism of these movements of the iris is very complicated; I have noticed that whenever the vessels dilate, the pupil contracts, and when the vessels contract, the pupil dilates.[22]

This relation between the blood-vessels of the iris and its movements has many important advantages; as, for instance, during sleep, when the vessels dilate, the pupil contracts, thus preventing the light from being felt too vividly. In inflammation of the eye, light exercises an irritating and injurious influence; but the vessels during inflammation are always dilated, the pupil is therefore narrower, and the light which strikes the back of the eye less intense, recovery being consequently more speedy.

After copious loss of blood, in fatigue, deep depression, in pain, and similar cases, the vessels contract and the pupil dilates, in this way allowing many things to be seen which would be imperceptible for want of light if the pupil were contracted.

All this seems perfect as an apparatus, but unfortunately it has grave defects.

Our eye is like a photographic machine, and the pupil acts like the diaphragm which photographers put before the lens, for in our eye, too, there is a lens similar to that of the photographic camera, behind the diaphragm of the iris. When there is little light, the photographer puts in a diaphragm with a wider opening, but then the picture becomes dull, because the rays of light in passing further from the centre of the lens and on its peripheral edge produce a picture with indistinct outlines. Photographers, therefore, in order to obtain a picture clear in all its parts, prefer a very strong light, and make use of a diaphragm with a very small opening. These are also the best conditions for distinct vision; for if we observe the eyes of a person who is looking into distance, or is absent-minded, and then hold a small object before him, we see that the pupil immediately contracts.

But this wonderfully perfect mechanism ceases to act as soon as the animal or the man is subjected to violent emotion. When the vessels contract during fear or a struggle, or in any other exertion, the pupil immediately dilates, and the picture loses in distinctness. If we watch fighting dogs, cats, or men, we at once perceive that the eye has become blacker, and that the pupil is at its maximum dilatation.

But how shall we explain, by means of the hypothesis of Spencer and Darwin, the fact that nocturnal animals present with equal precision the same movements in the expression of the forehead and eyes? Why, for the sake of such a small advantage as being able to see a little better when we have the light in our eyes, is there such a complicated muscular apparatus always in operation, while nature has not provided against a far more serious defect, as is the confusion of images caused by the too great dilatation of the iris?

In order to appreciate the extent of the defect of vision during emotion, I made the following experiment, together with Dr. Falchi. We took a small sample of writing from Snell’s tables, and then determined what was the greatest distance at which it could be easily read by a certain person; then, on some pretext, we scolded or reproached the subject in such a manner as to occasion a sudden and strong emotion. When we then requested the same person to read the writing, he was no longer able to do so at the same distance, but had to approach the tablet, often by a few steps, in order to see as before. A violent muscular exertion, a few turns on the trapeze or in the gymnastic rings, a race, the rapid ascent of a staircase, also diminish the acuteness of vision in a noticeable manner.

III

When one considers as a whole the symptoms by which fear reveals itself, one might almost think that it was a product of heredity and selection. Animals that are easily frightened, a disciple of Darwin would say, are those which can more easily avoid danger and save themselves; these produce young, and perpetuate their timidity in their posterity. But we know that the phenomena of fear are the morbid exaggeration of physiological facts. Animals cannot become continually more timorous by means of hereditary transmission; the necessity of struggling brings other faculties than those of flight and fear into play, and effect the preservation of the species in another way. Our organism is not such a perfect machine as to be able to resist or adapt itself to all conditions of environment; there are inevitable necessities against which selection is of no avail.

In my opinion, although we may accept the principle of Spencer and Darwin as an explanation of many things, we yet cannot extend it to all phenomena. Spencer and Darwin were not physiologists enough; in their studies of the emotions they did not sufficiently seek the causes of the phenomena observed by them in the functions of the organism. There are, so to speak, hierarchies in the parts composing our machine, for all functions are not equally important. But in the whole of the vital economy one notices the preponderance and supremacy of the blood-vessels. It is so indispensable that the organism should profit by all the material procurable for the nutrition of the nerve-centres, that the circulation of the blood in all parts (therefore in the eye also) is subordinated to this prime object.

In this way it seems to me the fact may be explained that the blood-vessels of the iris contract during strong emotions, notwithstanding that this produces excessive dilatation of the pupil, and that the back of the eye becomes anÆmic, although this contraction of the vessels of the retina is disadvantageous to distinct vision.

We often hear persons, speaking of some great fright, say: 'I was like one struck blind, I could see nothing.’ Travellers tell of serpents blind with fear, that bit the shadows and branches of the trees, blunting their teeth and shedding their poison fruitlessly.

Darwin maintains that there are two distinct causes for the frown which every little difficulty in a train of thought produces. One is very similar to that propounded by Spencer, of which we have already spoken; the other runs as follows: 'The earliest and almost sole expression seen during the first days of infancy, and then often exhibited, is that displayed during the act of screaming; and screaming is excited, both at first and for some time afterwards, by every distressing or displeasing sensation and emotion,—by hunger, pain, anger, jealousy, fear, &c. At such times the muscles round the eyes are strongly contracted; and this, as I believe, explains to a large extent the act of frowning during the remainder of our lives.’[23]

This explanation does not seem to me satisfactory, because it only pushes the question further back, and we must still ask: But why does the child frown when it cries? But, indeed, it suffices to render Darwin’s hypothesis improbable, if we call to mind that new-born children frown before they shed a single tear.

The following is the explanation which I offer of this phenomenon.

When we look intently at an object, we must contract all internal and external muscles of the eye. This is indispensable in order to effect the adjustment by which we modify the curvature of the lens in the interior of the eye; that is to say, we alter the lens according to the distance, in the same way as anyone looking through a telescope adjusts it by lengthening or shortening the tube. We have already seen that the pupil must contract when we contemplate an object close to us; thus we cannot direct our gaze towards our nose without a contraction of the pupil.

The most important movement of the external muscles of the eye is that by means of which we produce a convergence of the visual rays from both eyes on the object of attention. Thus, whereas the two eyes are parallel when we are absent-minded or gazing into distance, they converge when fixed on an object near us, as the hands would meet in order to take hold of it. All these movements are effected by a single nerve, called the motor-oculi, between which and the facial nerve there is a certain sympathy, as may be seen in the unconscious movement of the eyelids and forehead when we exercise the eye. And vice versa, when we close the lids, we move the eyeball without intending to do so. We may convince ourselves of this if we hold one eye shut with a finger and then close the lid of the other; immediately we feel the eyeball under the finger turn downwards.

The muscles of the eye contract also when we exert ourselves; for instance, if we try by night to look at a small distant light, at the same time lifting a heavy weight, or exerting ourselves in some other way, we see the light double, owing to the involuntary convergence of the eyes. I have photographed several persons during physical exertion, and many of them have quite the appearance of suffering, so pronounced is the contraction of the muscles of the forehead, although it was quite unnecessary. The arrangements of our organism are such that the energy, the tension of the nervous system diffuses itself in various directions, without the possibility, in certain cases, of restricting its influence to limited muscular groups. Thus, if we try to move the ear, the muscles which raise the corner of the mouth also contract; if we merely tell someone to close his eyes, we see the other facial muscles move, often causing involuntary grimaces. Again, we cannot move one eye to the right and the other to the left. Very few can turn the pupil upwards without raising the eyelids, or move the eyebrows separately. All this is due to the difficulty of localising the action of the will in the nervous fibres leading only to certain muscles; several groups of fibres seem always drawn simultaneously into the sphere of action, except when there has been much practice in discerning and selecting the fibres which shall accomplish an isolated movement, or when an intentional effort is made, which, however, is a matter of much difficulty.

When animals look attentively at some object, they turn their ears towards it. This movement, which they make in order to collect the sounds, must be preceded by a contraction of the muscles of the forehead and of those serving to turn the auricle of the ear. It is very probable that these movements, noticeable also in monkeys, have been preserved in man, although in attention he no longer moves the ears but only the muscles of the forehead.

In our nature psychic processes are so closely connected with their external sensory manifestations that it is impossible to check the manifestation of nervous activity in the muscles whenever the ideas appear to which these external movements stand in a permanent relation, even when this external communication is quite unnecessary. Thus we see that a man lost in thought gesticulates, making a hundred involuntary movements, and sometimes speaks, although no one is with him to whom he need communicate his ideas. And so it happens that we reproduce the characteristic movements of attention in forehead and eye whenever, in the various contingencies of life or in the development of ideas, an obstacle hinders the progress of thought. As soon as we begin any work which demands greater force of attention and reflection, we immediately and involuntarily put into action the mechanism of forehead and eye, which has always been made use of in intently scrutinising objects.

IV

All will have noticed that when we look intently at anything, all other objects become the more indistinct the further they are removed from the point of attention. This is because we have only one point in our eye in which vision reaches a maximum of acuteness. This point is called the fovea centralis, because it looks like a little dimple or funnel of two-tenths of a millimetre in diameter. If the image of an object falls at a distance of only a few millimetres from the fovea centralis, the eye can no longer accurately distinguish the colours. Red and green give an impression of palish yellow, violet appears blue. A little further distant, yellow and blue disappear completely, and only light and dark are perceived. This anatomical disposition of the elements destined to perceive the image and colour of objects obliges us to move the eye and bring it into relation with all parts of an object if we wish to examine it minutely. On this account no organ has such precise movements as the eye. If we look at our eye in a mirror, and move our head up and down, to the right and to the left, we see to our astonishment that the eye can remain fixed and motionless. Let the reader repeat this experiment in order to conceive the facility and precision with which the eye fixes on one point which we wish to look at attentively. The restlessness of the eye contemplating an unknown figure, the agitation which is visible in a man when he is afraid of another, and therefore examines him from head to foot in order to be ready to defend himself, or escape an impending danger, is an inevitable consequence of the structure of the eye, which cannot contemplate and embrace a wide field without moving.

When the object is not small enough to be embraced by the simple movements of the eye in its orbit, we bend and turn the head, or move the trunk to right or left; if that does not suffice, we move the whole body. Actors represent fear by exaggerating the attitude peculiar to one intently observing an object.

These movements are so spontaneous and natural, that it costs an effort to keep head and body still when looking at an object situated on one side of us. A feeling of profound contempt, hatred, or pride is necessary before we can pass close to a man with head stiff and erect.

V

Anyone who studies the parts of a machine can judge of the accuracy of its movements, because the structure of a machine represents its function; the dead organism is, therefore, no less important a field for observation and study to the physiologist than the living organism.

When we see, on opening the skull, that three nerves leave the brain to move the eye, and that six muscles are attached to this little ball weighing on an average seven grammes, we may conclude at once that perhaps no other organ has the same variety, independence, and rapidity of movement.

The eye is indeed unrivalled in the complication of its muscles and the number and variety of its nerves by any other organ except the tongue. This explains why both have their own language, and how they are able, by the infinite variation of their movements, to express every emotion of the mind.

The life of the eye lies entirely in its movement. A well-made glass eye which can follow the movements of the real eye can scarcely be distinguished from the latter when placed in the orbit, but when it remains motionless it gives to the countenance a dreadful, spectral appearance.

I have studied the expression of the eye in those born blind. These poor people, who could not even see dim shadows of objects, nor distinguish night from day, as though a sevenfold bandage covered their eyes, used to play instruments and be happy together, nor would anyone have thought that in them the eye was dead, insensible for ever to light; but it was only its movements which gave it an expression of joy and amiability, which inspired confidence and tenderness.

How eloquent is the eye of a dying friend looking at us for the last time, and seeming to reflect all the sadness of an existence fading while still full of hope and aspirations! The eye does not change for many hours, but when you come back to look at the cold semblance of your friend, and bid him a last farewell, the immovable look, the staring eye of death arrests you on the threshold; in it you read the anguish of pain, the horror of an overwhelming misfortune.

There are also in the pupil of the eye vivid expressions which are almost entirely unknown. It is curious to note in the eye of a dog, when quiet, how the pupil dilates and contracts at every emotion. This cannot arise from his looking at near or distant objects. The iris, like the blood-vessels, reflects every little emotion. We do not know these delicate shades in the language of the emotions, because the analysis of physical facts accompanying the expression of the passions has not yet become sufficiently minute and accurate. Between the maximum dilatation of the pupil, so characteristic of fear, and its greatest contraction in sleep, perfect calm and weariness, is the whole intermediate series of movements in which the passions are revealed. There are little alterations in the diameter of the pupil which pass unnoticed, unless one can look closely at the eye, but, by attentively observing a great number of persons, I have convinced myself that it is possible to read the effects of the passions in the movements of the pupil. When the edge of the iris grows narrower and the middle of the eye blacker and larger, it is a sign that we are agitated by a strong emotion which we try in vain to conceal, because the eye, as the poets say, is the window of the soul, through which we look into the depths of the heart.