_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]
[21] Ch. Darwin: _The Expression of the Emotions_. London, 1872, p. 10.
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]
[22] A. Mosso: _Sui movimenti idraulici dell’ iride_. R. Accademia di
Torino, 1875.
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]
[23] Ch. Darwin: _The Expression of the Emotions_, p. 225.
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.