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CHAPTER IX.
HALLUCINATIONS.
I.
HYPNOTIC hallucination, of which we propose to give a short sketch, is undoubtedly one of the most important phenomena of hypnosis; the attention of observers has long been directed to it, and it has been the subject of numerous experiments.
In the case of a subject sensitive to suggestion, the experimenter can produce the most varied hallucinations, and it may almost be said that there is nothing which suggestion cannot create. This observation will suffice, and we need not cite the innumerable instances of hallucinations given by some authors, who are more interested in experiments which amuse than in those which instruct. It is as unprofitable to enumerate all the species of hallucination which it pleases the observer to impose upon his subject, as to describe all the forms which a piece of clay may assume in the hands of its moulder. We shall, therefore, content ourselves with giving a few instances of the way in which hypnotic hallucination may affect all the senses.
Sight. — A false appreciation of the form of an object may be suggested, so that it appears to the subject to be
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larger, smaller, or misshapen. If, for example, the idea of some deformity of face in a given person is suggested, the subject, even when some hours have elapsed since his awakening, will regard that person with an expression of disgust or horror whenever he looks that way, and, indeed, the person in question may sometimes become an object of permanent dislike. We have employed this method with success in order to break off the relations between certain hysterical patients. The illusion may be carried so far as to produce a mistake with respect to the identity of a person; an hypnotic subject will in the waking state lavish caresses on a person whom she is known to detest, if during the hypnotic sleep it has been suggested to her that she has to do with some other person to whom she is attached, and the error will sometimes persist for a whole day, until the illusion is destroyed by natural sleep or by an hysterical attack. If the presence of a person who is really absent has been evoked during the hypnotic sleep, the illusion is equally persistent, and the subject may perceive an imaginary object throughout the day. At the word of the experimenter the laboratory becomes a street, a garden, a cemetery, a lake, etc; a portrait appears on a blank sheet of paper. It may even be suggested that there is a column of figures on the paper, which the subject will add up correctly. (Babinski.)
Hearing. — Influenced by suggestion, the subject confounds the voice of an unknown person with that of an absent acquaintance; he can hear, in the midst of profound silence, voices which issue orders, which repeat insults or obscene words, etc.
Taste.— If the subject is presented with a piece of
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paper, and told that it is a cake, he will begin to eat it with relish. In other cases, he may be convinced that his food is poisoned. If the idea of a nauseous substance is suggested to him, the sensation may be so intense as to produce vomiting.
Smell. — This sense may also become the seat of erroneous impressions. The subject may, for example, believe that a bad smell is coming to him through the keyhole, etc.
Touch. — The illusions and hallucinations of touch assume still more varied forms, and all forms of cutaneous sensibility may occur together or separately. The suggestion of a wound is one of the most curious of these hallucinations; the subject's description of his suffering varies with the suggestion that the wound was given by a sharp or blunt instrument, but his description is only correct if he has previously experienced one of these accidents. It is still more remarkable that the hallucination of sight is simultaneously developed: the subject sees the blood flow, etc., and a systematic delirium ensues which is more or less persistent, and during which he complains of imaginary suffering, applies appropriate dressings, and carries his arm in a sling, just as if the wound really existed.
Muscular Sense. — If an hallucinatory object, such as a lamp-shade, is put in the subject's hands, and he is told to press it, he experiences a sensation of resistance, and IS unable to bring his hands together.
Internal Sense. — Suggestion cannot only be applied to the senses; it is possible to produce visceral hallucinations and illusions, the sensation of a foreign substance in the interior of the body, etc. But the most remarkable
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of this group of suggestions, and the one which it is the most easy to produce, are those which refer to the calls of nature. When hunger or thirst has been suggested, the subject eagerly calls for food or drink as soon as he awakes, and if they are presented to him, he swallows them with avidity. If it is suggested that he wishes to make water, the subject is scarcely awake before he assumes an embarrassing attitude and hastens to satisfy the imaginary necessity. Sensual suggestions provoke equally imperious desires, of which the consequences may be imagined.
Nor is this all. Not only do the suggestions of imaginary sensations affect the senses and the viscera, but it is possible to suggest the idea that there is a change of structure in the whole substance. The subject may, for instance, awake in amazement, saying, "I am made of glass, do not touch me," and systematic delirium may ensue from this mistaken idea. Other forms of delirium may be created at pleasure, by the suggestion of a sensation affecting one of the special senses. Richet's observations on this subject, in the Revue Philosophique of March, I884, are worthy of notice, and we subjoin a few of them.
Mme. A —, a respectable matron, underwent the following metamorphoses: — As a peasant. She rubbed her eyes and stretched herself: "What o'clock is it? Four in the morning!" She drags her feet as if wearing sabots. "I must get up and go to the stable. Now, La Rousse, turn round!" She assumes to be milking a cow. "Leave me alone, Gros- Jean; leave me alone, I say, and let me get on with my work." As an actress. Her face, so harsh and dissatisfied a moment before, assumes
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a smiling expression. "You see my skirt? My director insisted that it should be longer. In my opinion, the shorter the better; but these directors are always annoying. Do come and see me sometimes; I am always at home at three. You might pay me a visit, and bring a present with you." As Archbishop of Paris. Her face assumes a very serious expression, and she speaks slowly, in a voice sweet as honey: "I must finish writing my charge. Oh, it is you, M. le grand vicaire. What do you want? I did not wish to be disturbed. . . . Yes, this is New Year's Day, and I must go to the cathedral. . . . This is a very reverent crowd, is it not, M. le grand vicaire? There is still a sense of religion in the people, whatever happens. Let that child come near, that I may bless him." She presents an imaginary ring for the child to kiss, and throughout this scene she makes gestures of benediction to the right and left. "I have now another task in hand. I must go and pay my respects to the President of the Republic. M. le President, I give you my good wishes. The Church wishes you a long life: in spite of the cruel attacks made upon her, she knows that she has nothing to fear as long as a perfectly honest man is at the head of the Republic." She pauses, appears to listen, and says aside, "Yes, yes, only false promises!" Then aloud, "Now let us pray;" and she kneels down.
We have observed some phenomena of the same kind, but in a less developed form. On one occasion we told X — that she had become M. F — , and after some resistance she accepted the suggestion. On awaking she was unable to see M. F — , who was present; she imitated his manner, and made the gesture of putting both her hands in the pockets of an imaginary hospital apron. From
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time to time she put her hand to her lips, as if to smooth her moustache, and looked about her with assurance. But she said nothing. We asked her whether she was acquainted with X —. She hesitated for a moment, and then replied, with a contemptuous shrug of the shoulders, "Oh yes, an hysterical patient. What do you think of her? She is not too wise."
It is difficult to define the psychical nature of these transformations of personality. In our opinion the phenomenon is more complex than that of hallucination, and constitutes true delirium. Moreover, many hypnotic hallucinations — that of hearing, for instance — have a secondary tendency to produce a delirium corresponding with their character.
The form of hallucinatory suggestion may be varied. We have begun by considering the hallucinations which relate to the present time, those which are realized as soon as the suggestion is given. It is possible, in the case of some subjects, to create an hallucination which is to be realized in a given number of days, weeks, or even months. A simple affirmation is enough to effect this experiment. The patient is told that when he enters the room on the following day he will see a crow perched on the table; or that two months hence, on the 1st of January, he will see the speaker come in to wish him a happy new year. The subject remembers nothing of this when he awakes, and the suggestion remains dormant in his mind until the date fixed for its revival. We shall have more to say on the subject of these experiments. On the other hand, retrospective hallucinations, which are really hallucinations of the memory, can also
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be given. It is, for instance, impressed upon the subject that at a given moment of his past life he witnessed the commission of a crime by an old man living in the same house with him (Bernheim), and if the suggestion is clearly defined, the subject's memory will be as intense and as full of details as if the fact had actually occurred. We can see what grave consequences might ensue from these experiments from a medico-legal point of view.
Unilateral Hallucinations. — The hallucinations hitherto in question are bi-lateral; the senses all agree to deceive the subject: what the eye sees, that the hand touches, and the ear hears. By means of suggestion, however, a subject can receive a uni-lateral hallucination, as when an imaginary object is presented to him which he can only see with one eye. Dumontpallier was the first to study this phenomenon, which is common in the insane, and may be produced in several ways. For instance, the subject is told, that there is a portrait on a blank sheet of paper, and it is added, after opening the right eye only, "You see this portrait?" Then this eye is closed and the other is opened, with the words, "You no longer see anything." On awaking the hallucination remains, localized in the right eye, with which the subject sees the portrait, while for the left eye the paper remains blank. The experiment, performed in this way, is simple enough. Dumontpallier has made it more complex by giving; different hallucinations to each of the two symmetrical organs, to each eye or each ear. Thus, after hypnotizing the subject, he says to the right ear that it is a fine, sunshiny day, while another person says to the left ear that it is raining. On the right side of the subject's face there is a smile, while on the left the lip
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is drawn down, so as to display annoyance at the bad weather. The experiment is continued by the intervention of sight and hearing, and the description of a rustic fête, attended by young people of both sexes, is transmitted to the right ear. This description is perceived by the left cerebral hemisphere, as it appears from the smile on the right side of the face, while on the left there is an expression of emotion, caused by the imitation of the barking of a dog at that ear. It is said that the different expression of the two halves of the face is most striking. These bilateral hallucinations, which may also be sometimes observed in the insane, are very interesting from a psychological point of view. Dumontpallier thinks that they may be taken as a proof of the functional independence of the two cerebral hemispheres.*
In connection with this order of ideas, we will adduce a fresh fact, which we have repeatedly observed. Suppose the idea is given to the subject that a white cardboard appears red to the right eye only; if he closes the left eye while looking at the cardboard with the right eye, it appears to be of a brilliant red; if he uses both eyes, the colour appears to be pink. It is probable that the sensation of whiteness received by the left eye exerts an attenuating effect on the hallucination of the right eye, and thus produces the degradation of colour. The two following facts are connected with this experiment: — If one eye is fixed on a red square, and the other on a white surface, the sensation of red persists, but it is eclipsed from time to time as if by a white cloud. If a red image is produced in one eye after gazing fixedly at
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a green square, and the other eye is then opened on a white surface, the consecutive monocular image is soon effaced. The experiment of the unilateral hallucination of colour holds a middle place between these two; the hallucinatory red image is weakened by the sensation of whiteness received by the other eye, but it is not so much weakened as the consecutive image, and it is more weakened than the actual sensation. With the exception of these differences in intensity, the three phenomena may be referred to a single fact, belonging to the study of optics, and termed the concurrence or struggle of the two fields of vision.
Nor is this all. The result is complicated if it is suggested that the cardboard appears red to the right eye, and green to the left eye. In the subjects observed by us, we have not found that there was a confusion of the two suggested colours, but a species of conflict: at first the cardboard appeared to be red, and a moment after it was green, and this alternation of colour seemed to perplex and weary the patient's sight. This second experiment may be explained like the former one, by the struggle between the two fields of vision. In the normal state we find that this struggle occurs when two different colours, such as red and blue, are simultaneously presented to the right and left eyes. The subject does not, as might have been supposed, see a composite colour, but a kind of mist floating over both colours, and occasionally displacing them. Finally, on looking through the stereo-scope at two similar images, one white and the other black, the colour of the images is not fused into a uniform grey, but a conflict takes place between the two fields of vision, so that at one time the bright, at the
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other the obscure, shade predominates, and hence there results the impression of a shining surface.* These well-known phenomena seem to explain the experiments on hallucinations which we have mentioned above.
Before going further, we must draw some psychological conclusions from the facts just enumerated. Most modern psychologists accept the law indicated by Dugald Stewart, and more regularly developed by Taine,+ according to which every image involves a momentary belief in the reality of its object. Dugald Stewart observed that few men could look from the top of a high tower without experiencing a sensation of fear, although their reason convinces them that they run no greater danger than if they were standing on the ground. ''In fact,'' as Taine adds, ''on looking suddenly down, we imagine ourselves to be suddenly thrown headlong to the bottom, and this imagination only terrifies us, because for an imperceptible moment of time it is a belief. We instinctively draw back, as if we felt ourselves falling.'' In every image presented to the mind there is, therefore, the germ of an hallucination, which only needs development. Such development occurs in the hypnotic state, in which it is only necessary to name a given object to the subject, simply to say, ''Here is a bird!'' in order that the image suggested by the experimenter's words should become an hallucination. Thus there is only a difference of degree between the idea of an object, and the hallucination of that object.
There is one striking fact to be noted, namely, that
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most of the patients whom we have employed as subjects of experiments in hallucination are, in the waking state, endowed with a special power of representing objects in a sensible form. Liébault regards this quality as the sign of individuals susceptible of hypnotism. Without fully accepting this opinion, we believe that persons who have what Galton terms the power of visualizing, are more susceptible of visual hallucinations than others. When we request one of our subjects to picture to himself an absent person, he soon declares that he sees that person as distinctly as if he were actually present. This vivid power of representation is frequently found in hysterical patients, and it explains why, when such patients are gathered together, they, by exchanging confidences or by imparting their respective impressions, reciprocally hallucinate each other.
When susceptible and hysterical subjects have been hypnotized by the same experimenter for several days, they often end by remaining in a state of permanent obsession; they are, so to speak, possessed, both by day in the waking state, and at night during their dreams. This state of mind is accompanied by spontaneous hallucinations of varying form, but of which the experimenter is always the object. One patient will have an incubus, another will be tormented, embraced, etc. If several subjects meet under the same conditions, and confidences are exchanged, a species of epidemic of hysterical delirium ensues, in which the hallucinations will be followed by impulses, acts of violence, etc., which would account for the different phases of the drama which terminated in the death of Urban Grandier. One of the present writers was present at a scene of this nature, which showed that
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such methods of experiment ought to be conducted with the utmost care.*
As we have just seen, hallucination consists in the vivid external projection of an image. But these terms have the defect of treating the image as a thing, as a unity. Yet reflection soon shows that this assumed unity is composed of numerous and heterogenous elements — that it is an association, a group, a fusion, a complexity, a multiplicity.+ The image o£ a ball is the resultant of complex sensations of sight, touch, and muscular sense. It is, therefore, interesting to know if, when an image is associated by contiguity with several others, the external projection of the first image involves that of the others. This occurs in numerous cases of hallucination which may be referred to the action of the memory. Heidenhain gave a series of hallucinations to a hypnotized student, in which he went to the hippodrome, and then to the Jardin des Plantes, where he saw the lions come out of their cages. When, some time afterwards, the subject was again hypnotized, the same series of hallucinations occurred spontaneously. So, again, if the subject was reminded of his normal life, or, rather, if an hallucinatory suggestion was made to him, the memory of subsequent events was evoked in its turn, and formed a tableau or hallucinatory scene. In this way a subject may be constrained to live over again a part of his life, and secrets are revealed which would never have been uttered in the waking state, nor even perhaps under hypnotism. We may, for example, cite the story of the singer given by
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Mesnet. If a curved stick was given to him, which he took for a gun, his military recollections revived; he loaded his gun, crouched down, took aim and fired. If a roll of paper was given to him, and a light was flashed across his eyes, recollections of his present profession of singer at a café-chantant were aroused; he unrolled the paper and sang loudly. Finally, if a story is told to the subject, and he is then hypnotized, it is not impossible that as soon as he is put upon the track, he may have an hallucination of all the events in succession, as they were related to him.
This tendency of hallucinatory images to suggest themselves shows that the law of the association of ideas by proximity may be exerted without the participation of the subject's intelligence and will. One image provokes another, in virtue of the bond which unites them, and in the same way the second suggests the third. This is one of the clearest manifestations of cerebral automatism.
In pushing the analysis a little further, it may be observed that in these kinds of hallucination it is not merely the image, taken by itself, which is externally projected, but the bond of association which unites several images. It is, in fact, this association which formulates the hallucination; it produces the successive projection of the images in the order in which they are grouped in the mind. This proves that the law laid down by Dugald Stewart with respect to the states of consciousness also applies to the relations of these states. In reply to the question, What is meant by external projection? we answer that it is the belief in the reality of a thing. The external projection of an image
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is, therefore, the belief in its reality. So that, if it is true that we are inclined to make an external projection of the associated images existing in the mind, this implies that we are inclined to believe that things are in reality associated together, just as their images are associated in the mind. This is no new idea; a considerable time has elapsed since it was formulated by Stuart Mill, and it is confirmed by the facts of hypnosis in the most striking manner.
Speaking generally, we may say that, whenever two images are in association, an implicit affirmation of the existence of a relation between two things ensues; this is an opinion which, therefore, must be referred to an association of externally projected images.
II.
One of the most striking characteristics of hypnotic hallucination is the permanence of its localization. Take the hallucination of a portrait, which is instructive in many respects. If, by means of suggestion, a portrait is caused to appear on a sheet of cardboard of which both sides are alike, the picture will always be seen on the same side of the cardboard, and in whatever direction it may be presented to him, the subject will always place it in the position which it occupied at the moment of suggestion, so that the picture may not be inverted, nor even inclined. If the cardboard is turned round, the portrait is no longer seen, and if it is turned upside down, the portrait is seen with its head downwards. The subject never mates a mistake; if his eyes are covered, or if the experimenter stands behind him while
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changing the position of the object, his answers are always in conformity with its original localization.
This fact is still more clearly shown by an experiment devised by one of the present writers.* We place a blank card on a blank sheet of paper, and with a blunt pointer, which does not, however, touch the paper, we follow the outline of the card so as to suggest the idea of a black line. We ask the subject, on awaking, to fold the paper in accordance with these imaginary lines; he holds the paper as far from him as it was at the moment of suggestion, and he folds it so as to form a rectangle which precisely covers the card.
Charcot has often repeated a curious experiment which fundamentally resembles the foregoing one. It is suggested to the subject that there is a portrait on a blank card, which is then mixed with a dozen others which appear to be precisely similar. The subject is requested, on awaking, to run his eye over these cards, which he does without understanding the reason, but when he comes to the card on which the imaginary portrait was traced he sees it at once.
All these experiments seem to imply that the hallucinatory image produced in the subject by verbal suggestion does not remain in his brain in a vague and floating state; it is probable, as one of the present writers has shown,+ that this image is associated with some external mark — a dot, for instance, or a raised spot, — some distinctive feature of the blank card which was shown to him when the suggestion was made, and this association of the
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cerebral image with an external mark would explain the series of facts of which we have given an account. One detail of these experiments is significant. If, instead of putting the pack of cards into the subject's hands, we show him the imaginary portrait while holding it two yards from his eyes, the card still appears to him to be white, although a real photograph would appear to be grey. If the card is gradually brought nearer to his eyes, the imaginary portrait becomes visible, but it must be brought much nearer than an ordinary photograph before the subject can say for whom it is meant. This peculiarity can be explained on the assumption that the hallucinatory image is evoked by distinctive marks on the card which are only visible at a short distance. So again, the subject cannot distinguish the portrait through a sheet of tissue paper placed upon the card. With the help of an opera glass, the subject can recognize the object of hallucination when it is too far for him to perceive it with his naked eye, and the same explanation applies to this experiment, although there is an air of paradox about it.
Without going further into the matter, these observations may be summed up in the following formula: The imaginary object presented by hallucination is perceived under the same conditions as if it were real. This formula has served as our guide in a series of experiments on visual hallucination, which we have endeavoured to modify by optical instruments. We proceed to indicate the most important results of these researches into what Janet terms hallucinatory optics.
The origin of these researches is found in an early experiment by Brewster, which was performed in the
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following way: — It is well known that if, in the normal state, a finger is pressed upon the eye so as to divert it from its normal position, and at the same time the individual looks fixedly at some external object, his sight is doubled, and he sees two objects instead of one. Brewster performed this experiment on a subject who had visual hallucinations, and pressure on the eye caused a duplication of the imaginary object. Paterson tells us that this curious experiment was repeated in analogous circumstances by a student subject to hallucinations. When this student was crossing a garden, he perceived a phantom, wrapped in a large blue cloak, standing a little way off under a tree. The student desired to verify Brewster's famous experiment, and pressed one eyeball, which only had the effect of rendering the figure less distinct. But on looking obliquely he saw the same figure double, and of the natural size. This observation has been confirmed by others. Ball mentions an hysterical female servant who was subject to ecstatic crises in which the Virgin appeared to her in a splendid robe; pressure on the eyeball caused a duplication of the vision, and she beheld two Virgins.
This experiment of duplication has served as the point of departure for researches intended to establish the reality of the subjective phenomena produced in hypnotic subjects.* It occurred to one of the present writers to substitute a prism for pressure on the eyeball. If, when regarding external objects, a prism is placed before one eye, the objects appear to be double, and one of the images presents a deviation of which the direction
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and extent may be calculated. If, during the hypnotic sleep, it is suggested to the subject that a profile portrait is on a table of dark wood before him, he distinctly sees this portrait on awaking. If, without warning, a prism is placed before one eye, the subject is astonished to see two portraits, and the position of the false image is always in conformity with the laws of physics. Two of our subjects answered correctly in the cataleptic state, although they were unacquainted with the properties of the prism. Moreover, by concealing its edges they may be deceived as to the precise position in which it is placed. If the base of the prism is uppermost, the two images are placed one below the other, and if the base is lateral, the images are side by side. Finally, the table may be brought so near that the duplication of the image ceases, and this will serve as an index.*
This experiment with the prism is only a variation of the one performed by Brewster. The prism, as well as ocular pressure, exerts two distinct actions on the hallucinatory image — that of duplication and of deviation. Deviation by means of the prism is a more accurate phenomenon than when it is effected by ocular pressure, since, when the position of the prism and its distance from the object is known, it is not only possible to predicate its direction, but to estimate its extent. It is an interesting fact that, in the case of a given distance, the prism produces or fails to produce a duplication of the image in proportion as the sight of the eye is more or less normal This same remark applies to the vision of real objects in the waking state.
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One of the present writers* has substituted other optical instruments for the prism, in order to verify and develop the former experiments. An opera-glass brings imaginary objects nearer, or makes them appear further off, just as if the objects were real. We begin by suggesting a given hallucination, either placed upon the wall of the laboratory or, which is better, on a screen covered with white; it may be a bird perched upon the wall, a lizard which runs up it, a flower, or a picture hung upon the wall. If the subject is made to look at the hallucinatory object through an opera-glass, it appears to be nearer or more distant, according to the end of the glass presented to his eye. It is well to guard against imposture, by not allowing the subject to see which end of the glass is in use. It is the simplest arrangement to have two cards of equal size, each pierced with two openings, and fastened with sealing wax to both ends of the opera-glass. This will prevent the subject from perceiving real objects on the field of the glass, which might, owing to the changes of dimension, serve as an index of its position. For the same reason, a plain and even surface should be chosen as a background for the hallucination.
It is interesting to observe that the opera-glass will not make the object appear more or less remote unless it has been adapted to the subject's sight. Thus W— , who is short sighted, could see nothing through a glass which had been adapted to C—'s long sight. Hence the subject must be requested to adapt the glasses to his sight before he is hypnotized. A great difference may be observed in the way in which subjects are affected by the experiment. C— and D— merely declare that the
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imaginary object is at one time near, at another far off; and this change of distance does not surprise them; only if an unclean beast is the object of suggestion and he is made to appear close to them, they utter a cry of terror.
W—, who is much more intelligent, always evinces the most lively astonishment. When a bird perching on the branch of a tree is the object of suggestion, she cannot understand why it should be close to her at one moment and far from her at another. If we tell her that the bird is moving from place to place, flying nearer or further away, she rejects this explanation, and replies that the tree also seems to change its position. She finally concludes that her eyes are affected, so as to change the apparent distance of objects, which is a reasonable, if not a just conclusion. These reflections are all made during the state of somnambulism.
This experiment with the opera-glass may be modified by making use of hallucinatory portraits. The portrait of a given person may be made to appear on a square of white paper, and a series of experiments may be performed on this imaginary portrait, which are only a development of those with the opera-glass, since a final analysis must refer them all to an application of the laws of refraction. If a magnifying glass is placed before the imaginary portrait, the subject declares that it is enlarged, and if the lens is sloped, the portrait is distorted. If the sheet of paper is placed at a distance equal to twice the focal length of the lens, the portrait appears to be inverted. These experiments do not always succeed, but if under favourable conditions they are successful in only one instance, they must be accepted as genuine.
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Again, a prism with three equal facets is passed over the white paper, and the subject is requested to look through it at the portrait, beginning with its upper part; he sees two heads instead of one, and these heads are enlarged in a direction corresponding with the orientation of the prism. Now, we must observe that the surface of the paper on which the prism is placed is perfectly white and smooth, so that no one ignorant of the properties of a prism could perceive that it doubled the image of the subjacent morsel of paper. If again the paper is applied to one facet of the prism, the subject sees only a single portrait, which seems to be folded in two. These appearances all conform to the reality; the subject would see the same series of modifications if there were really a picture on the paper. Under similar conditions a doubly refracting crystal gives two images, which are modified by revolving the crystal on its axis.
The last experiment of this nature is that with the microscope. The question arises whether, if a given preparation is supposed to be mounted on a microscopic slide, and the subject is made to examine it through the microscope, the hallucinatory image will appear to him to be magnified; whether this enlargement will be sufficient to reveal to him structural details which are invisible to the naked eye; whether, for instance, he will distinguish the corpuscles in the drop of blood suggested to be on the slide, or if he will see the stomata in a fragment of vegetable, epidermis. The experiment is difficult, since most of the subjects who look at the microscopic slide fail to discover the imaginary preparation. Repeated attempts have convinced us
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that the microscope enlarges the hallucinatory image — that a spider's foot, for example, becomes enormous, — but we have not observed that hypnotic subjects discover details invisible to the naked eye.
It is much more easy to obtain the reflection of an imaginary object in a mirror. It may be suggested to the subject that an object is placed on a given point of the table, and if a mirror is placed behind that point the patient immediately sees two objects. If, for example, the appearance of one cat is suggested, a second is likewise seen, but the two objects are not always alike. On one occasion we gave to our subject the hallucination of a white cat, and the mirror caused another to appear, which was of a grey colour. The reflection of the imaginary object appeared to the subject to be just as real as the imaginary object of suggestion. Thus, when the mirror was in its place and the subject was told to look at the beautiful butterfly perched upon the table, she at once exclaimed that she saw two butterflies. When desired to catch them both, she made the gesture of seizing the one perched before the mirror, and fastened it with a pin to her bodice. This at least was done by D—, while C— refused to be so cruel as to run a pin through the butterfly. She then tried to catch the second butterfly, of which she saw the reflection in the mirror, but as her hand came in contact with the glass, she was unable to reach the spot which the butterfly seemed to occupy. It was curious to observe W—'s behaviour at such a time. After knocking her hand against the glass several times in succession, she gave it up with indignation; disregarding our orders, she absolutely refused to repeat the attempt, saying, ''I cannot
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do it, I cannot do it.'' It may easily be shown that the subject does not place the imaginary object on the surface of the mirror, but sees it within the mirror. In fact, if the mirror is advanced, withdrawn, or inclined, so that it could no longer reflect the supposed object, the double vision ceases.
These primary experiments are rude. They may be summarily explained by saying that the subject sees the mirror, and logically concludes that the object of suggestion must be reflected in it. We do not assert that this phenomenon of auto-suggestion is impossible, yet it seems to be excluded by the following experiments: — We recur to the hallucination of a portrait, which we have already employed, and shall have further occasion to employ. A prism of total reflection is placed upon the blank sheet on which there is an imaginary portrait. The resemblance of this prism to a mirror cannot warn the subject of what is to follow, and yet he never fails to see a second portrait, like the first one, when he looks at the hypothenuse facet of the prism. If the portrait is then placed opposite to a mirror, and it has been suggested that the profile is turned to the right, it appears in the mirror to be turned to the left. The reflected picture is therefore symmetrical with the hallucinatory image. If, without allowing the subject to see what is done, the paper is turned upside down, the reflected portrait also appears to be inverted, and, which is to be noted as in agreement with the laws of optics, the profile is turned to the right. We repeat that the imaginary portrait is turned to the right, and in the mirror it is turned to the left, but that if the paper is inverted, it appears to be turned to the right. Such combinations would not
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be invented, and a still more complex experiment maybe performed. An inscription of several lines may be substituted for the portrait, and in the mirror it is inverted and runs from right to left. If the paper is turned upside down, so also is the reflection of the inscription, and at the same time it ceases to run from right to left. This experiment frequently, but not invariably, succeeds, and that in a way which excludes all suspicion of fraud. Yet few persons are aware that, while reflected writing must be read from right to left, this condition ceases when the reflected writing is inverted. Such difficulties do not exist for the hypnotic subject, who only sees and does not reason.
Since the imaginary object created by hallucination acts in all respects as if it were real, it may be asked whether that object is concealed by the interposition of a screen. This depends upon the subject, and the results are extremely varied. In the simplest case the hallucination is destroyed by the screen, and the subject declares that he has ceased to see anything. In the case of other subjects the screen has not this effect, the hallucination persists, without any change of place, and if the subject is ordered to seize the object of suggestion, his hand goes to the other side of the screen in search of it. In other subjects, again, the imaginary vision is not interrupted by an opaque body, but the object is transferred to that body.
We are unable to assign a cause for these variations, which may be noted in different subjects, and sometimes in the same subject, in the course of a series of experiments. We need only remark that peculiarities of the same kind occur in the vision of real objects during
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somnambulism. In some somnambulists the vision of real objects is not destroyed by the interposition of a screen, and it is destroyed in others. It must be clearly understood that these experiments were not concerned with the wonderful phenomena of vision through a thick bandage, of which so much was said in former times, and for the demonstration of which the Burdin prize was offered by the Academy of Medicine. We have not, strictly speaking, to do with vision through a screen, but with an hallucinatory vision which persists in spite of interposed screen, which is very different. The inconstancy of these phenomena, however, decided us not to make them the object of continued study.
The logical connection of the foregoing experiments will be readily seen. The first in date and importance is that of ocular pressure. This is a curious discovery, which must serve as a starting-point for a whole series of fresh researches, and it is the first instance of experiment on hallucinations, although it has been long neglected, and has only become fruitful in our own day. The prism experiment is merely a variant on that by Brewster; instead of the mechanical deviation of the eye produced by the finger, the prism causes the deviation of the luminous ray before it enters the eye, but the result of double vision is the same. The experiment with the opera-glass, again, may be regarded as a development of that with the prism, since both instruments are founded on the laws of refraction of light. Finally, the mirror is as closely connected with the preceding experiments as in physics the phenomena of the reflection of light are connected with the phenomena of refraction. All these new facts are logically derived from Brewster's experi-
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ment, which virtually includes them all, just as the properties of lines, angles, and surfaces virtually include the whole of geometry. It is only necessary to deduce and support each deduction by experimental research.
In order to give a satisfactory explanation of these experiments, we must decide between three hypotheses. 1. A suggestion is made; the subject is aware that a prism is placed before his eyes which has the property of duplicating objects, or an opera-glass which enlarges them, etc. But this first hypothesis must be rejected, since it is evident that the subject is ignorant of the complex properties of the lens, of the simple prism, the bi-refracting prism, and of the prism of total reflection, and although the subject may be acquainted with the other instruments, such as an opera-glass, care is taken to conceal them in the performance of the experiment. Therefore, unless we suppose that the experimenter has been incautious enough to announce the result beforehand, it must be considered certain that suggestion in this sense has had nothing to do with it. 2. The optical instruments employed have modified the real objects in the subject's field of vision, and these modifications have served as an index from which he could infer similar modifications in the imaginary object. Although this second explanation is better than the former one, it appears to us insufficient. It is opposed by numerous facts already cited — by the precise localization of the hallucination on a point which the experimenter is only able to find by the aid of elaborate measurements; by the recognition of an imaginary portrait on a blank card mixed with other cards which appear to us precisely the same; by the inversion of the imaginary portrait when
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the card itself is inverted, without the suhject being aware of it, etc. We adopt a third hypothesis, which has already been indicated. 3. The hallucinatory image is associated with external and material marks, and the modifications produced by the optical instruments on these marks modify the hallucination in their turn. The following observations seem to confirm this theory.
We will first give an account of the experiments performed by Marie and Azoulay, on the duration of the perception of the imaginary object. These observers have shown that it takes a longer time to perceive an imaginary object than when the object is real.* The apparatus consists of a white strip placed on Marey's cylinder; as the cylinder revolves, the strip passes before a spy-glass of somewhat small diameter, through which the subject looks. At the moment when the subject sees the white strip, he gives an electric signal. The precise moment at which the strip passes before the glass is known, so that in order to ascertain the time of personal reaction it is only necessary to measure the period which elapsed between that moment, and the moment when the signal was given.
In the first series of experiments we estimated, in the case of an hysteric patient attended by Charcot, the time of reaction in the waking state, making use of a real white strip. This time was on an average 0-18", and it was the same in the case of a normal individual. In the state of somnambulism the time was 0-20'', that is, it was increased by 0-02"; We then, instead of employing a real white strip, suggested to the hypnotized subject that there was a white strip on a certain part of the
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blackened cylinder, although there was in fact absolutely nothing to distinguish this part of the cylinder. We told the subject to indicate the moment at which she saw the imaginary white strip. The time of reaction was 0-22". "We then awoke the subject and again estimated the time of reaction. In this case the average was 0-23".
"It remained to be seen whether this average varied during the period of suggestion. On the following day, after the lapse of twenty-four hours, we found that the time of reaction was 1-02", and after forty-eight hours it was 1-114!". We could not carry our researches further, since at the end of seventy-two hours the suggestion had vanished, and the subject could no longer see the strip on the cylinder.
"These are the two points on which we wish to insist: first, on the value of these experiments as a means of verification, since, as we were able to ascertain, simulation is absolutely impossible. However intent the subject may be, he cannot, either by sight or by the employment of some rhythm, succeed in producing such a tracing as those we have obtained, since in these tracings all the times of reaction agree almost perfectly. Therefore, the images furnished by suggestion may, as well as the real images, be checked by the graphic method. Secondly, the time of reaction increases enormously, but not in direct proportion with the duration of the suggestion.
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Seconds.
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Immediately after suggestion it is ...
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0-23'
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Twenty-four hours after it is ...
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1-02"
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This is an increase of ...
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0-79"
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Forty-eight hours after it is ...
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0-114"
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This is an increase of ...
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0-093"
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In a second series of experiments, the relative values of the time of personal reaction was the same, although each was slightly raised to the amount of 0-02or 0-03"."
The primary fact to be deduced from these experiments is that for the perception of a real object the time of reaction is 0-18"; for that of an imaginary object it is 0-23". The probable reason for this difference is that in the vision of a real colour, there is only a single phenomenon — the sensation received by the eye. On the other hand, in the vision of an imaginary colour, fixed by suggestion on an external point, two things are involved — the vision of the point, and then the appearance of the imaginary colour on that point. This double phenomenon must occupy more time than a simple sensation. Moreover, as time goes on, the association between the point in question and the hallucinatory image is relaxed, until at last it disappears, since the moment comes when the point ceases to arouse any image in the subject's mind. Hence we understand why the duration of the time of reaction increases up to the moment when the perception ceases altogether. The graphic method has the advantage of seizing these progressive modifications in the duration of the imaginary perception, delicate phenomena which completely escape from simple observation. For this reason the experiments by Marie and Azoulay have a real psychological interest, teaching us how to measure the force of a mental association as it becomes weaker.
Londe, chief of the chemical works at the clinical establishment of the Salpêtrière, informed us of the following fact, which is a remarkable instance of protracted suggestion, confirming the ideas just set forth.
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On one occasion when an hysterical patient was in a state of somnambulism he approached her, and showed her a plate, representing a view in the Pyrenees, with asses ascending the hill, and said, ''Look at your portrait. You are quite naked.'' The subject happened to see the plate when she awoke, and since she was furious at seeing herself represented in a state of nature, she jumped upon it, and broke it. Two photographs had, however, been taken from the plate, and these were carefully preserved. The patient's fury was excited whenever she saw them, since she always saw herself represented naked, and after two months had elapsed the hallucination still remained.
This extraordinarily long survival of the hallucination is easily explained by the theory of distinctive marks. In fact, photography presents to the subject an immense number of such distinctive marks, which become associated with the hallucinatory image and evoke it with invincible force by accumulating their effect; The most curious feature of this observation is that the subject did not see these distinctive marks, or, rather, it did not occur to her what they really were, since she must have seen them in order to project her hallucination. She failed to see, however, that their combination formed a view in the Pyrenees. The effort to convince the subject of her error was fruitless; she only saw her own portrait.
There is another remark to make on Londe's observation. This hallucination of the portrait existed in the case of all the proofs of the same photograph. It was first produced by the plate and then transferred to the copies printed off from it; the imaginary portraits equalled in number the printed copies. This multiplication of
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the hallucination by the multiplication of the distinctive marks somewhat resembles the phenomenon of the reflection in the mirror; at any rate, it clearly proves with what force the fictitious image was associated with the sight of the photograph, since the presentation of a new, but entirely similar copy was apt to suggest the same hallucination.
We repeat that if the hallucination of a portrait is created on a real photograph, the subject will discover the same portrait on a second copy of the photograph without the intervention of any fresh suggestion. This, which was at first an isolated experiment, led us to invent another which is logically derived from it. A blank card on which suggestion had fixed an imaginary portrait was photographed, and when we presented this photograph of the blank card to the subject, she instantly recognized the imaginary portrait. But it is evident that experiments of this kind are too delicate to be invariably successful. Just as experiments in physics sometimes miss fire, so it is with experiments in cerebral physiology. The one which succeeded had, however, a great demonstrative value, since it was the first. We made a second attempt, which completely failed, and we have made no further attempts.
This same theory of distinctive marks may explain some other points. It leads us to understand why hypnotic hallucination persists in many cases after the subject awakes, while the memory of what occurred during sleep is completely effaced, at least unless certain expedients are used to revive it. The contrast is striking. The subject is ordered to commit a murder, and on awaking, he neither remembers the order he has received.
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nor the act he is supposed to have performed. Yet if the hallucination of a bird has been given, it will be almost as vivid after awaking as it was during somnambulism, and for this we may ask the reason, since if the hallucination is an image, so also is memory. This is true, but the hallucination is an image with the addition of some external, distinctive mark, and this distinctive mark, which is still present, recalls the hallucinatory image by means of the association of ideas, like a knot tied in a pocket-handkerchief
The existence of this distinctive mark establishes a natural transition between the hallucination and the illusion of hypnotism. The two phenomena are both produced by verbal suggestion; the only difference between them is that there is a substratum for the illusion which is wanting in the hallucination; in the case of every illusion there is a real object which is more or less transformed by the suggestion. It must be admitted that this is not an essential difference, since suggestion may transform the object in a thousand ways. A book may become a hat, a dog, or a person, and precisely the same appearances may be created without the aid of any object. For those who accept the theory of distinctive marks this difference between hallucination and illusion is completely effaced, and hypnotic illusion appears to be an hallucination for which the special suggestion has selected a distinctive mark which happens to be a real object. Hence some interesting consequences ensue; the hypnotic illusion is modified, just as an hallucination is modified in accordance with the real object to which it is applied.
We have seen that in the case of hallucination these
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modifications consist in phenomena of deviation, duplication, etc., produced by optical instruments. In the case of illusion, since the distinctive mark is not a mark, but a real object, and often a person, it may be spontaneously modified, and this adds a fresh complication to the experiment. A gentleman named X— was transformed by suggestion into a dog. The subject no longer saw X— , who ceased to exist for her, but she ascribed all his gestures and movements to the dog which had been suggested to her. Hence it followed that the illusion had not the fixed character habitual in hallucination, but constantly varied, and all the changes which took place in X— reacted on the illusion. On one occasion we pointed out X— to one of our subjects, saying, ''Do you see that person? She is a nurse, carrying an infant.'' The hallucination persisted on awaking, and the subject looked at the nurse and child with feminine curiosity. Strangely enough, she watched X—'s gestures, and ascribed them to the nurse, so that the real and the imaginary were closely intermingled. When X— raised his hands, she said angrily, ''Wretched woman, is that the way to carry an infant? Do you wish to kill it?"
Hypnotic illusion leads us by a logical transition to the ordinary and physiological illusion of the senses, which occurs in so many different circumstances, and of which every one has had experience. The cause of these two illusions is not the same, since hypnotic illusion is produced by verbal suggestion, that is, from within, and the illusion of common life is generally produced by the imperfect perception of external objects, that is, from without. Yet it cannot be doubted, in
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spite of this difference in the formative process, that every kind of illusion is formed by the synthesis of two elements — the external element and the false image constructed by the mind and projected on the object. We may add the ordinary illusion may, like the other, be magnified by a lens, reflected by a mirror, etc., as some of our observations prove. In this case these optical modifications seem to be quite natural, since the false image is associated with an external object. It is, however, an interesting fact that a common law dominates the whole series of phenomena, hallucination, hypnotic illusion, and normal illusion.
Nor does the series end here. The normal illusion of the senses is directly connected with the external perception, that is, with the normal act by which we enter into relations with external and present objects. External perception is termed by Taine a true hallucination. Certainly this act is, like illusion, a synthesis of external sensations with internal images. The study of the mechanism of perception by one of the present writers leads to the conclusion that it presents on a small scale the phenomena which occur on a large scale in hypnotic hallucination — deviation, duplication, and enlargement of the mental images. Hallucination must, therefore, be a disease of external perception.*
The theory of distinctive marks may be extended to hallucinations which are given for some remote period; a singular fact which conflicts with our scientific experience, so that doubt has been thrown upon it.
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Bernheim * said to S—, formerly a sergeant, when he was in a state of somnambulism, "On what day will you be at liberty during the first week of the month of October?" He replied, "On Wednesday." "Then, listen to me. Go to Dr. Liebault on the first Wednesday in October, and you will see the President of the Republic, who will give you a medal and a pension." He said that he would go, but remembered nothing of it when he awoke. On the 3rd of October, however, sixty-three days after the suggestion, S— presented himself at Dr. Lidbault's, at ten minutes to eleven. On entering he met and saluted F—, and then, without paying attention to any one, he went to the left side of the library, made a respectful salute, and uttered the words, "Your Excellency." As he spoke rather low. Dr. Liébault went up to him, and at that moment he extended his right hand, saying, "I thank your Excellency." Liébault asked to whom he was speaking, and he replied, "To the President of the Republic."
Beaunis informed the Société de psychologie physiologique (April, 1885) of another instance of post-hypnotic hallucination, which was realized six months after the suggestion. On the 14th of July, 1884, he told a hypnotized young woman that she would see him enter her room on the following 1st of January, and wish her a happy new year. And so, in fact, it was. On New Year's Day the young woman saw Beaunis (who was in reality in Paris) enter her room, wish her a happy new year, and disappear. Suggestions of dreams which would occur on some subsequent night have also been given. Our observations lead us to believe that hallucinations
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given for some remote period really take effect. The length of the intervening period is less surprising than the fact that they are realized at the fixed hour.
It may be asked whether hypnotic subjects possess an abstract power of measuring time. We think it more probable that the occurrence of the hallucination at the moment assigned beforehand is produced by some external circumstance, and that if this circumstance, which acts as a stimulus, is removed, the latent existence of the hallucination may be indefinitely prolonged. It must be observed that in the experiments by Bernheim and Beaunis the day fixed for its fulfilment bore a distinctive mark. In the one case it was the first Wednesday of October, in the other the 1st of January. These dates perhaps served as the subject's distinctive mark; it was as if he had been told that the hallucination would occur when the experimenter clapped his hands, and the advent of the moment which had been named served as a kind of signal. This explanation must, however, be regarded as provisional, and the question, like so many others, remains open.
III.
We next propose to describe a series of hypnotic experiments which seem to throw some light on the still obscure problem of the physiology of hallucinations. In fact, the new phenomena with which we are about to acquaint our readers appear to show that hallucination is produced by an excitement of the sensory centres. If the conclusion is not new, it is, at any rate, interesting, and although it has often been set forth by physicians of
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the insane, no complete proof of the hypothesis has hitherto been given. Such a proof is furnished by the careful study of hypnotic phenomena.
We must, however, hasten to add that we are less anxious to develop a theory than to register a certain number of facts which are interesting in themselves inasmuch as they are facts. The conclusions which we draw from them with respect to the physiology of hallucinations are merely the bond which serves to connect very varied observations, and it is these alone which have any value. The regular observation of any phenomenon remains as a definite acquisition to science, whatever afterwards ensues, while the future of theories is uncertain.
1. Achromatopsia. — We will first consider achromatopsy, or colour-blindness. Paul Richer, in his Etudes cliniques sur l'hystero-epilepsie, was the first to show that in the case of most hysterical subjects it is impossible for their vision to accept hallucinations of colour. Since the eye has lost its chromatic sensitiveness, it cannot see the colours of an imaginary object.
As one of the present writers has shown, the same rule seems to apply to the spontaneous hallucinations of insanity. We observed in the St. Anne asylum, of which Dr. Magnan is in charge, an insane, hysterical patient who was constantly haunted by the image of a man dressed in red. The left side of this woman's body was affected by anaesthesia and achromatopsia, and when her right eye was closed, she continued to see the hallucination with her left eye, but instead of being dressed in red, the man appeared to be in grey, and enveloped in mist.*
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Since the fact is proved, it has still to be explained. It may be considered strange that a somnambulist subject is capable of receiving all sorts of hallucinations, however absurd they may be; that in the course of a few minutes she may be surprised by the appearance of a ball, a public fête, the overturning of a carriage, a tumultuous crowd, an insurrection, a conflict before barricades, succeeded by a quiet, moonlit night, revealing the bodies of the dead. The patient who sees all this may laugh, weep, be amazed, or utter cries of terror, in correspondence with the scenes unrolled before her; but when the attempt is made to display some coloured object to her, the experimenter's power is suddenly arrested, and the automaton, who is so docile in all other respects, obstinately asserts that she does not see the colours suggested to her. For instance, if the eye which remains open has lost the perception of violet, it is impossible for that colour to enter into any of her hallucinations, unless the other eye, which retains the sense of that colour, is opened. This is a striking fact, but it will cease to appear absurd when we bestow upon it sufficient reflection. It can be satisfactorily explained when we consider the seat of achromatopsia, and the probable seat of the hallucination.
It is now almost certain that hysterical achromatopsia results from a functional disturbance of the cerebral cortex, and not from any lesion of the retina, or of the media of visual perception. All that we know of the nervous disturbances of hysteria leads us to believe that they do not involve these media, and that we must regard achromatopsia as a functional disturbance of the cortical cells concerned with the perception of
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colour. This belief leads to the conclusion that if this functional disturbance is the same hindrance to the hallucination as to the perception of a given colour, it is probably because these two phenomena, perception and hallucination, employ the same class of nervous elements. In other words, hallucination occurs in the centres in which the impressions of the senses are received, and it results from an excitement of the sensory centres.
It may be objected that in the case of some hypnotized subjects achromatopsia is no hindrance to the suggestion of coloured hallucinations, but we find it easy to explain this deviation from the rule. The achromatopsy of hysterical subjects depends on hemi-ansesthesia, and there is nothing definite in this lesion. It is not so much a paralysis as a paresia, a slothfulness of the nervous elements. These elements no longer respond to the call of their normal excitant, the coloured ray, yet it is not surprising that they should react when approached from a different direction, by an excitement which proceeds from the auditory centres, and which is merely verbal suggestion.
2. The phenomena of contrast. — There is another fact which shows, still more clearly than the one just given, that hallucination and sensation have the same seat in the brain, namely, the property with which the hallucinatory image is endowed of producing the same effects of contrast as those produced by sensation. Parinaud, the head of the ophthalmological laboratory of nervous diseases at the Salpêtrière, has been good enough to send us the following paper, relating to hitherto unpublished experiments, which are of an extremely interesting character: —
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"Hallucinations of colour may develop phenomena of chromatic contrast as readily as, and with even greater intensity, than the actual perception of colour.
"If, for instance, a piece of paper divided by a line is presented to a hypnotized subject, and it is suggested to her that one half is red, the sensation of the complementary colour, green, occurs on the other half. If, after awaking, the sensation of red remains, so also does the sensation of green.
"In order to understand the meaning of this fact, I must refer to the following experiment, relating to chromatic contrast, which I communicated to the Société de Biologie in July, 1882.
"A card which is half white and half green on one side, and wholly white on the other, is marked in the centre on both sides with a spot intended to fix the vision. For half a minute the eyes are fixed on the parti-coloured side, and then the card is turned and the eyes are fixed on the central spot of the white side. On the half which corresponds to the green half a red tint appears, which is merely the definitive after-image, and on the other half the complementary green tint is seen. The after-image of red has, therefore, developed by induction the sensation of green in the part of the retina which had only received the impression of white. This experiment, which may be varied in different ways, so as to establish the fact that we have to do with positive sensations, and not with any error of judgment, shows that every impression of colour leads to a more or less persistent modification of the nervous elements which produce the after-image
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and that this modification causes, in the parts not affected, a modification in the opposite direction which develops the complementary sensation, by a phenomenon analogous to that which occurs in a magnetized body.
The image of hallucination acts like the after-image, and may likewise cause an induced sensation, so that it corresponds with a material modification of the nervous centres.
In order that the experiment should succeed, it is necessary that the subject should retain the perception of the suggested colour, for we know that the perception of colours is frequently affected by hysterical amblyopia. If there is any blindness with respect to this colour, the suggested sensation is confused, and the induced sensation does not occur. When the subject is able to distinguish all the colours in the waking state, she can also distinguish their complementary colours. When only unable to distinguish certain colours, which is often the case, a singular result follows. Suppose that the subject sees red, and cannot see green, the hallucination of green cannot develop the induced sensation of red; yet the hallucination of red, which she sees, may develop the induced sensation of green, which she cannot see."
It clearly appears from these experiments that from the point of view of simultaneous contrast, the hallucinatory image acts precisely as a real sensation would do, whence it may be concluded that the two phenomena effect the vibration of the same keys of the cerebral instrument. They are, however, distinguished by the following difference. When a real sensation of colour is experienced, the sensation results from an excitement of
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the retina, and it reaches the centre of visual sensation by the paths of vision, by the optic nerve, the chiasma, the optic tracts, etc. The sensation of colour suggested by words, that is, the hallucinatory image, results from the excitement of the organ of hearing, and it is reflected in the centre of auditory sensation before it reaches the centre of vision. With the exception, however, of this difference in the process of excitement, we repeat that the hallucination and the real sensation appear to correspond with the same physiological process, since otherwise the same effects of chromatic contrast would not occur in both cases.
3. Subjective Sensations. — Parinaud's researches into the simultaneous contrast naturally led to the inquiry whether hallucinations produce subjective sensations, since these two orders of phenomena are closely allied.
Let it be remembered, for the sake of clearness, that the term of objective sensations is given to the perception of images which follows the impression on the sight of a luminous or bright object. The image which ensues is positive or negative, according to the conditions under which it is seen. In the positive image we have the representation of the object as it really is; its colour and the relatively luminous intensity of its parts are maintained. Conversely, in the negative image the light parts of the object appear to be dark, and the dark parts to be light; and its general colour is exchanged for the complementary colour.
The production of after-images is a normal phenomenon which constantly, but with varying intensity, accompanies the exercise of external vision. We have ascertained that hallucinatory vision is subject to
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the same conditions; every hallucination of some persistence is succeeded, on its disappearance, by an after-image, just as in the case of ordinary sensations which affect the retina.*
This phenomenon was first observed, several years ago, by the physiologist Gruithuisen. Observing what occurred in his dreams, he states that "sometimes a bright, fantastic image was succeeded by one of the same form, but indistinct. Sometimes, again, after dreaming of violet fluor-spar, or burning coals, he perceived a yellow patch on a blue ground."+
We had occasion to verify the exactness of this observation in our treatment of hypnotic patients. The somnambulist subject was requested to look attentively at a square of white paper, with a black spot in the centre, designed to fix her vision. At the same time the suggestion was made that the paper was of a red or green colour. A second square of paper, likewise marked in the centre with a black spot, was then produced, and as soon as the subject had fixed her eyes on the spot, she exclaimed that the spot was surrounded by a coloured square, and the colour indicated was complementary to that which had been made to appear by means of suggestion. This complementary colour is the negative image left by the hallucinatory colour; it lasts but a short while, it is effaced, is lost, or dies, as the subject says, and it resembles in all respects a normal, negative image.
This experiment was repeated by Charcot before a numerous assembly, during one of his lectures on aphasia.
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That eminent professor demonstrated that, in order to ensure success, care must be taken to define the nature of the suggested colour. For instance, if only the colour red is suggested, the subject may either see the shade of red, of which green is the complementary colour, or the orange-red, of which blue is complementary. These contradictory results are impossible when the colour which the subject is intended to see is made clear by a comparison. It may be remarked in passing, that this experiment is a peremptory reply to those who still believe in the existence of a general simulation. It would be unreasonable to maintain that an hysterical woman, who scarcely knows how to read or write, has the theory of complementary colours at her fingers' ends. Our subjects have always answered correctly, and, which is more important, the correct answer has been given when the experiment was performed for the first time.*
It must be remembered that analogous phenomena occur in the mental vision of normal individuals. The persistent idea of a brilliant colour develops an after-image of the complementary colour, just as a real sensation does.+ If we close our eyes and fix our minds for a long while on an image of some vivid colour, and then open our eyes to look at a white surface, we shall, for a brief space, see the object of our imagination, but of the complementary colour. One of the present writers successfully repeated this experiment, which is difficult and demands from the subject a great power of visualiza-
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tion. He was able to picture to himself the idea of red, so intensely that at the end of a few minutes he was able to see a green patch upon the white paper; but, strangely enough, repeated efforts were required before he was able to associate an outline with the colour, so as to reproduce under the form of a subjective image the idea of a coloured cross or circle.
These facts show the close connection which unites sensation, hallucination, and memory. These three phenomena are evidently based on the same physiological operation, and are effected in the same region of the nervous centres. Thus, whether it is a real impression of the colour red, whether the colour is pictured by the memory, or again, whether it is seen by an hallucination, it is always the same cell which vibrates.
4. The Mixture of Imaginary Colours. — Since it is interesting to develop an experiment, so as to consider a fact in every aspect, we sought to discover what would result from the mixture of imaginary colours. We wished to know whether an hypnotic subject could make white out of the suggested colours of combined red and green. The process which, after many attempts, we found to be the most convenient, does not involve much preparation. Two squares of coloured cardboard are placed on a table at a little distance from each other, and a piece of glass is held before the eye at such an angle as to admit a direct view of one of the squares, and at the same time a reflected image of the second square; in this way it is easy to place one image over the other, and thus to mix their colours. The result may be varied in manifold ways by employing differently coloured squares. After this arrangement is made, a series of blank cards are
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shown to the subject, and it is suggested to him that they are coloured. Care is taken each time to define the suggested colour by showing to the subject, by way of pattern, one of the coloured cards which were used for the previous experiment. In this way the imaginary colours of the white cards are absolutely the same as the real colours on the other cards.
The subject may then, with a piece of glass and his collection of cards coloured by suggestion, effect the same mixture of colours as the experimenter, who can on each occasion verify the exactitude of the result by the combination of the real colours. Under these rigorous conditions, which leave no scope for erroneous suggestions, the imaginary colours give the resultant shades which are in conformity with optical laws. Hence we may conclude that the hallucination of a colour is a suggested sensation which occupies the same region of the cerebrum as a real sensation.
5. Phenomena observed with reference to the Eye. — We now come to a consecutive series of clinical observations and of experiments which furnish a valuable argument in proof of our thesis, and which are perhaps the most decisive of all. When a lesion of the brain produces sensory disturbances in the integuments of the eye, visual disturbances also occur, such as achromatopsia, or concentric or lateral contraction of the field of vision. This has been shown by numerous observations.* This singular relation between the general sensitiveness of the eye and its
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special sensitiveness is particularly apparent in the hemi-anaesthesia of hysterical patients. In fact, in these cases, the insensibility of one-half of the body not only extends to the skin and mucous membrane, but also to the other organs of the senses: sight, smell, and hearing are likewise affected on the same side; in a word, there is, as a rule, a sensitivo-sensorial hemi-ansesthesia. Under these conditions the general sensitiveness of the eye, the sensitiveness of the conjunctiva and of the cornea, is always in correspondence with the special sensitiveness of that organ. Thus the hemi-anaesthetic hysterical patients whom we have observed, and in whom there was neither contraction of the field of vision, nor achromatopsia, retained the sensitiveness of the conjunctiva. Those who had lost the power of seeing one or more colours, or whose field of vision was more or less relatively contracted, did not only experience anaesthesia of the conjunctiva, but also of the cornea. In this latter case, if while the subject is looking intently at any object, the conjunctiva and the cornea are touched by a strip of paper, the eye and eyelids do not move as long as the foreign substance does not come in front of the pupil. The reflex movement of the eye and eyelid which occurs in the latter case is exclusively produced by the excitement of the retina, which has lost the perception of colour, but still distinguishes light and shade.
In those who are simply hemi-anaesthetic, or who are totally anaesthetic with a predominance on one side, magnetization, statical electrization, etc., will effect a transfer of the anaesthesia, so as to furnish a counter-proof, affording constant results.
This relation between cutaneous and sensorial in-
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sensibility does not only exist when the anaesthesia extends to one-half of the body, but when it is more restricted. When statical electrization has destroyed the hysterical ansesthesia, after an interval which varies in different subjects, insensibility reappears in a localized region, which does not correspond with the distribution of the nerves. In the case of one of our patients, insensibility first returned to a limited zone round the eye, which included the cornea and the conjunctiva, and visual anaesthesia was reproduced, simultaneously with the limited anaesthesia of the skin.*
Another proof of the relation which exists between the special sensitiveness of the eye, and the sensitiveness of the conjunctiva, may be found in the observations we made on three hysterical and hypnotic patients at the Salpêtrière. Two phases of catalepsy may be distinguished, as far as the eye is concerned: First, in profound catalepsy, such as is produced by a sudden noise, the eyes remain fixed, with no movement of the eyelids. In this state it is possible to touch the conjunctiva without producing any reflex action. Secondly, when an object is moved to and fro before the subject's eyes, so as to fix his gaze on the moving object. If in this case the conjunctiva is touched, there is an immediate reaction of the eyelids, as in a healthy subject, although the insensibility of the rest of the body is maintained. The experiment may be repeated at pleasure by again throwing the subject into a state of profound catalepsy, and the result is always the same;
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as soon as the fixed gaze ceases, the sensitiveness of the conjunctiva returns. The object which is moved to and fro excites the special sensitiveness of the eye, just as under other circumstances a strong local excitement brings back the sensitiveness of the skin, and together with the function of sight the sensitiveness of the external membrane of the eye returns.
These facts appear to indicate that in some indeterminate region of the brain there are sensory centres common to the organs of the senses and to the integuments by which they are covered.*
This long preamble brings us to the observations in which we are more immediately interested, which regard the physiology of hallucinations. One of the present writers has ascertained that when a cataleptic subject receives a visual hallucination, the general sensitiveness of the eye is often profoundly modified. We have just seen that in the cataleptic state the conjunctiva and the cornea, with the exception of the region of the pupil, are generally insensitive. In the case of the subject P—, as soon as a visual hallucination was developed, the sensitiveness of the external membranes of the eye returned; the membranes could not be touched by any foreign body without producing reflex action of the eyelids.+ An hallucination arouses the general sensitiveness of the eye, just as it is aroused by waving a real object before the subject's eyes. This is surely a proof that visual hallucination excites the visual centres.
A second experiment displays the same fact under
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another form. In M—'s case the visual hallucination usually persisted for three or four minutes after awaking. As soon as this subject awoke, she complained of pain in the eyes and constantly rubbed them, only ceasing to do so when the hallucination disappeared. We saw this behaviour repeated more than forty times without attaching any importance to it, so true is it that we only see what we expect to see. And yet the phenomenon is curious; the hyperaesthesia, or rather the dysaesthesia, of the integuments of the eye is produced by the visual hallucination, since it lasts for the same period and disappears at the same time. If an hallucination brings about this modification of the cutaneous sensitiveness of the eye, it is probable that it excites the special sensitiveness of that organ, in other words, the centre of vision.* We observed another form of the same phenomenon in the subject X—. We suggested to her the hallucination of a bird perched on her finger, suggesting at the same time that she only saw the bird with her right eye. The hallucination persisted after awaking; the subject fondled the bird without being aware that she only saw it with one eye, for both eyes were open, nor did it occur to her to close one of them. After a while she complained of pain in the right eye, saying that she felt as if sand had got into it, and she only put her hand to this eye. It should be observed that persons aflfected by conjunctivis complain of the same sensation of sand in the eye. The localization of the pain in the right eye proves that the dysaesthesia depended on the hallucination.
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Each of these facts, taken alone, is insignificant, but they are in logical agreement and connection, and appear to prove that visual hallucination has its seat in the visual centre. After studying the influence of hallucination on the organs of the senses, and on the eye in particular, we must mention the observation made by one of the present writers* on the state of the pupil in subjects of hallucination. He observed in the first place that in the hallucinations which accompany the third period of a strong hysterical attack, the diameter of the pupil varies with the assumed distance of the hallucinatory object. This interesting fact also occurs in the hallucinations produced by hypnotism. This was what we observed in the case of two hysterical patients with whom it was possible to hold oral communication during catalepsy. When we desired them to look at a bird perched on a steeple, or flying high in the air, the pupil was gradually dilated until its normal diameter was almost doubled. When we caused the bird to fly down, the pupil gradually contracted, and the same phenomenon was reproduced as often as the idea of any moving object was evoked.
"The modifications of the pupil produced in this manner in a cataleptic subject, who continued to display all the phenomena peculiar to catalepsy, show that the fictitious object of hallucination is seen just as if it actually existed, and its supposed movements produces efforts of accommodation which are governed by the same
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laws as if it were a real object. We, therefore, have to do with a true hallucination, and not with any imposture."
IV.
We have now to observe how hallucination is affected by aesthesiogens. We have had frequent occasion to speak of aesthesio-genic agents. The term is applied to certain agents which, according to Burq, whose observations have been confirmed and extended by other scientific men, have the property of acting on the sensibility and motor power of a certain category of subjects. The magnet is the aesthesiogen to which we have most frequently had recourse. There is nothing mysterious about this agent; compared by physics to a solenoid, it acts like a faint electric current on the nervous system, and produces a continuous peripheral excitement. Its mode of action has, moreover, been clearly established by one of the present writers.*
We need not in this place prove the reality of aesthesiogenic influence, in order to reply to those who only see in these agents the effects of suggestion and of expectant attention, since we have already had occasion to explain this point. It only remains to show that in the following experiments we took sufficient care to eliminate suggestion and expectant attention. These were the points on which we insisted: 1. Since these researches were new to us, we were in many cases unable to foresee what would occur, and especially with respect to the polarization of emotions, so that suggestion
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on our part was impossible. 2. We repeated the experiments on absolutely fresh subjects, and obtained the same results. 3. The same effect was produced when the magnet was concealed under a cloth. 4. This was also the case when the magnet was made invisible by suggestion. 5. We made use of a wooden magnet, and nothing occurred, although if there had been any results they could not have afforded a counter-proof, since they might have been explained by the recollection of a previous peripheral excitement. 6. The experiments made under somnambulism were in logical connection with those made under lethargy and catalepsy, although in these two latter states we have found our subjects incapable of receiving any complex suggestion. We think that under these conditions the results we have obtained must be considered due to aesthesiogens, and not to unconscious suggestion.
Many observers may attempt to verify our experiments, and if they fail they will declare them to be false, or to have been produced by suggestion. Let them remember Claude Bernard's remark, that for the most part a negative experiment only proves that it has been imperfectly understood. It is clear that aesthesiogens only act on a certain class of subjects; this was admitted at the outset by all observers who have studied this question. Since our experiments with aesthesiogens are only the logical development of the experiments in metallo-therapeutics made by Burq and his successors, they are clearly subject to the same conditions. Our researches will not be invalidated by showing that they failed with the first subject who was presented to them; such an argument would be irrational. We do not dis-
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believe the phenomenon of neuro-muscular hyper-excitability, because it cannot be produced in a healthy subject, not affected by hysteria. Our present and future opponents are recommended to perform their experiments exclusively on the hysterical patients who display the features of profound hypnotism, and in those whose sensitiveness and muscular strength are modified by the application of magnetism.
We have observed that in the case of some subjects affected by profound hypnotism, unilateral hallucination may be transferred by the magnet, like a contracture or an hysterical paralysis.*
Contrary to what occurs in contractures, the transferred hallucination of vision is not symmetrical with the initial hallucination. It is suggested to the subject that he sees a portrait in profile on a card, and that this profile is turned to the right; it is added that he only sees this profile with the right eye, not with the left. By applying a magnet the hallucination is transferred from the right to the left eye; if the subject is then asked to which side the profile is turned, he says, as before, that it is turned to the right, although symmetry demands that it should be turned to the left.
During the transfer, the subject spontaneously complains of pain in the head, shooting from side to side. This pain is not diffused but local, and its seat is noteworthy. The cranio-cerebral topography established by one of the present writers+ enables us to show that the point where pain is confidently indicated by the subject
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coincides, in the case of certain forms of hallucinations, with the sensory centres of the cerebral cortex, just as they have been established by the physiological and anatomical researches of late years (Fig. 9). This is
Fig. 9. — Cranio-cerebral topography. — B, Bregma; C, Point corresponding with the outer extremity of the coronal suture; L, Lambda, corresponding with the parieto-occipital fissure; C S, Fissure of Sylvius; R R', Sulcus of Rolando; K, Its anterior extremity, about three centimeters behind the outer extremity of the coronal suture; R', Its posterior extremity, forty-five millimeters behind the bregma; A A, (Condylo-alveolar plane; B O, Auriculo-bregmatio plane; G L, Plane passing through the minimum frontal transverse diameter and the lambda; K E, Section passing between the two folds of the third frontal convolution at the point C, which corresponds with the external extremity of the coronal suture, and just touching the head of the caudate nucleus; R' H, Section passing through the posterior extremity of the sulcus of Rolando, and behind the posterior border of the optic thalamus: N M, Horizontal plane passing over the upper surface of the corpus callosum, and below the grey nuclei.
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especially the case with the most important hallucinations, those of sight and hearing. Thus, in the transfer of an hallucination of vision, the point is a little behind and above the pinna of the ear, corresponding with the region of which the destruction causes blindness and hemianopia; it is, therefore, the posterior part of the lower parietal lobule.
In the transfer of an hallucination of hearing, the pain is seated in the centre of the space included between the anterior part of the pinna of the ear and the external, angular process of the frontal bone. The pain almost corresponds with the centre of the temporo-sphenoidal lobe, and approximatively with the region of which the destruction causes deafness. For the sense of taste, the point is above the external occipital crest, two centimeters from the median line. For the sense of smell, it is one centimeter above that line. These two latter localizations are not in agreement with the results of anatomical and clinical researches, and demand revision.
It may be asked how this coincidence should be interpreted: whether it proves that the physiological process in correspondence with the hallucination is seated in the sensory centres of the cerebral cortex, behind the motor zone, or if we are only to regard it as one of the reflex acts, termed in physiology, an echo of pain. We cannot decide this question, since it is only certain that in the case of some subjects there is a special relation between some points of the external covering of the head, and certain nervous centres of which the exact locality is still undefined. On this account the seat of the pain of transference must be estimated as an objective sign.
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In another experiment on the same subjects, we obtained a demonstration of the same relation between certain points of the hairy scalp and certain sensory functions. This was in experiments on partial somnambulism.* If the subject is thrown into a state of total catalepsy, and those points of the scalp which become painful during the transfer are then mechanically excited by the finger or by some other blunt object, curious results are produced. On exciting that point of the scalp which corresponds with the centre of vision, both the subject's eyes are affected by somnambulism; they lose their cataleptic fixity, and follow the movements of the finger. If the point corresponding with the auditory centre is excited in a similar way, somnambulism affects the organ of hearing, and the subject who, up to that movement is completely insensible to the voice, hears the orders addressed to him and attempts to execute them, so far as his limbs, which are still cataleptic, allow.
We have seen what effect is exerted by the aesthesiogen on unilateral hallucinations; it displaces, and subjects them to a series of oscillations. When the hallucination is bilateral, the result is different; it is not a transfer, but what we have termed a polarization.+ Of this we will give some instances.
The usual hallucination of a bird perched on her finger was given to a somnambulist subject. While she was caressing the imaginary bird, she was awakened, and a magnet was brought close to her head. After the lapse of a few minutes, she suddenly paused, raised her eyes
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and looked about her in astonishment. The bird which she supposed to be on her finger had disappeared. She looked about the room, and finally discovered it, since we heard her say, So you leave me thus! The bird presently disappeared again, and once more reappeared. The subject complained from time to time of pain in the head at the point already described by us as corresponding with the centre of vision.
The magnet exerts the same suspensive effect on a real perception. For instance, after awaking one of our subjects, we showed her a Chinese gong and the pad with which it was sounded. The sight of the instrument alarmed the subject, and as soon as it was struck, she fell into a state of catalepsy. After this preparatory experiment, she was awakened and requested to look attentively at the gong, and meanwhile a small magnet was brought close to her head. In the course of a minute she asserted that she could not see the instrument, and that it had completely disappeared, and when the gong was sounded, more loudly than before, she did not fall into a state of catalepsy, but only looked about her with an air of some surprise. Hence it appears that the magnet in some sense paralysed the vision of the gong; the perception of this object was replaced by a corresponding anaesthesia, so that the noise of the gong no longer produced catalepsy.
We have also ascertained that the magnet destroys a suggested memory, just as it destroys both real and imaginary vision. This analogous effect is intelligible, since all these phenomena have a common basis. Memory is an image, and so also is hallucination, and an image is only a faint copy of an anterior sensation.
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Memory, hallucination, and true perception are distinguished by the secondary states of consciousness which accompany the suggestion of the image. In the case of memory, this state consists in the reasoning which localizes the image in the past. In hallucination and true perception these states consist in reasoning which localizes the image in the external world. But these localizations in space and time are secondary, accessory, superadded acts.
One experiment on polarization clearly shows the connecting link between these three phenomena. When one of our subjects was in the waking state, we spoke to her of the gong, begging her to describe its form, colour, size, and use. She repeatedly told us that she saw it distinctly in her mind. When her attention had been firmly fixed on the idea of this object, we applied the magnet, and in the course of a minute she had a difficulty in picturing the gong to herself, and ended in being unable to understand us when we spoke of it. We then took the gong off a table which stood near, and offered it to the subject, who did not see it. Even when it was sounded with considerable force, she only gave a slight start. But after waiting a few seconds, a consecutive oscillation took place; her recollection of the gong returned, together with the vision of the instrument, and then a slight stroke upon the gong sufficed to throw the subject into a state of catalepsy.
Thus we see that the suppression, or rather the paralysis of memory, produced by the application of the magnet, induces a corresponding paralysis of the perception of the object. Since the subject was unable to picture the gong to herself, she was also unable to see it when it was presented to her.
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The foregoing account describes the action of the magnet on a sensation, an hallucination, a memory, either by suppressing them or by substituting a corresponding
Fig. 10. — Red cross.
paralysis. There is an additional element in polarization, the production of a complementary phenomenon. This
Fig. 11. — Rose-coloured cross with green rays between its arms.
is shown by the following experiment, to which we must limit our description. We have seen that after looking intently at a red cross, and then on a white
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surface, a green cross appears as the consecutive sensation; in the subjective image the primitive colour is replaced by its complementary, but the form of the cross still persists. The same thing occurs when the hallucination of a red cross is evoked, or when the same coloured figure is presented to the imagination with sufficient intensity.
Fig; 12. — The cross has disappeared, leaving a space. The green rays have become elongated and of a darker shade.
If we inform one of our subjects, W— or C— while in the waking state, that the cross we have just drawn on a piece of white paper is coloured red, and if we then request him to consider this cross attentively while a magnet is, without his knowledge, placed behind his head, we have the following result: the subject sees green rays appear between the arms of the cross, these rays gradually become elongated and at the same time
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the original red tint of the cross changes to pink. For an instant the cross appears to be green, and then all colour disappears from the original figure, and the subject perceives a blank cross, a space surrounded by the persistent green rays (Fig. 12, p. 271). If at this moment a red cross is placed over the outlined figure, the subject is unable to see it. The magnet produces analogous effects on the memory of coloured objects.
It would be interesting to apply similar experiments to the senses of taste, smell, and hearing, in order to ascertain whether in the case of these sensory organs it is possible to establish a theory of complementary sensations, comparable to those of vision. We have merely had occasion to observe that under the influence of the magnet a suggested impression of heat is replaced by an impression of cold, which causes shivering.
V.
In the case of some subjects, the hallucination begins and ends during somnambulism. In others it is more permanent, and persists during the waking state. It will be easily understood that the duration of post-hypnotic hallucination is very variable, since it depends on many circumstances. In the case of subjects whose hypnotic hallucinations continue in the waking state, it is interesting to inquire what the hallucination becomes in its new environment. It might at first appear that the subject would on awaking correct her hallucination and in some sense expel it from her intelligence, but this is by no means the case. In subjects affected by profound hypnotism the hallucina-
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tion which persists in the waking state is accompanied by blind confidence. It is useless to tell the subject that she is the victim of an illusion, and that the portrait which she thinks she sees is an imaginary vision. She regards such language as a mockery, and if it is repeated the subject becomes uneasy and assumes a distracted air, and indeed on one occasion an hysterical attack appeared to be imminent. These facts seem to show that a conviction of the reality of the hallucination is an essential part of the phenomenon; the hallucination does not merely consist in the external projection of a sensible image, but in the condition of mind which accompanies the projection of this image.
On one occasion we informed our subject before hypnotizing her, that we were going to suggest an hallucination, and we agreed that she should, on awaking, make every effort to correct the hallucination and regard it as false. After hypnotizing her, we gave her the suggestion that a gold ten-franc piece, bearing the effigy of Napoleon III., was lying on the table. When she awoke, she still saw this coin. We said to the subject, "You know what we agreed upon. We gave you an hallucination, and the gold coin is not really there." She looked at us with a stupefied air, or I might almost say in a stupor, our words seemed to her so amazing. The mere idea that it was possible to doubt the existence of a piece of money which she saw and touched seemed to disturb her intelligence. But she soon recovered herself, and positively declared that she saw the coin, that it was a real coin, and that we were laughing at her in asserting the contrary. It was impossible to infuse the slightest doubt into her mind. The hallucination might be destroyed
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by suggestion, but as long as it remained, the subject believed it with all her might.
On the other hand, many writers have declared that it was only necessary to tell the subject that the hallucination was suggested to destroy his belief in the reality of the vision. We have only met with this submission in our subjects when the hallucination was fading away, and had lost its intensity.
We have still to say how the hallucination which has been produced may be destroyed. It is often very important to leave no trace of a sensory disturbance which may have dangerous consequences for those who are brought in contact with the patient. Any subject of hallucination is as dangerous as some explosive substance. In many cases the hallucination is spontaneously effaced, and this mode of disappearance has been well described by some subjects. The imaginary object loses its distinctness of outline, it becomes transparent, and ceases to conceal the real objects before which it is placed, and it finally seems to melt into air (Richer). In other cases, the hallucination disappears during the waking state, after an interval which varies with the subject. Some are in despair when the imaginary object disappears. One subject, to whom Bernheim had given imaginary rings, bracelets, and fans, implored him to leave her in possession of these gifts, since experience had taught her their fugitive nature. Others try to find some mode of accounting for this strange disappearance.
X—, who, at the end of a few days, saw the portraits which had been suggested to him fade away, and the cards become blank, explained the fact by saying that the photographs had been badly focused.
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The simplest mode of destroying the hallucination is to assure the subject that he has seen, heard, and felt nothing. Sometimes he resists this intimation. The magnet may also be employed, if the subject is sensitive to this aesthesiogen; we have already seen that the magnet rapidly destroys a bilateral hallucination. For the most part, the hallucination and all recollection of it disappears together; such amnesia may even occur when the hallucination has been produced in the waking state, and this is a valuable note by which we may ascertain the sincerity of the experiment.
This is the place for mentioning some curious phenomena. A somnambulist was shown a real scent bottle, which was on the table, and it was then removed, and she was told that it was still there. On awaking she saw the imaginary scent bottle, and was unable to see, smell, or in any way perceive the real one. It was placed in her hand, passed over her face, struck with a key, and she was not the least aware of it. The perception of the real object was completely paralysed by the imaginary vision of the same object.
Here is another example. The hallucination was given to X that one of the present writers attended a ball which is annually given at the Salpêtrière; she saw him distinctly and spoke to him several times during the ball. He came to the Salpêtrière on duty on the following day, in reality this time, and not in hallucination. X— saw, but did not recognize him, taking him for a stranger. It was necessary to hypnotize her in order to restore the perception of his person.
An hallucination may also be destroyed by a simple physical excitement. It is suggested to a somnambulist
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that she hears a letter repeated, L, for example. On awaking she continues to hear the same sound. On opening her mouth it is ascertained that the movements of her tongue coincide with each mental act of hearing. If this movement is checked by an energetic pressure, the hallucination disappears. It also disappears if the subject protrudes her tongue, and keeps it in this constrained attitude, or again if a contracture is produced.
We see, therefore, that an hallucination may be destroyed by three different processes, by suggestion, by physical excitement, and by the magnet. It is probable that the two latter agents really act by suggestion.
Hallucination, of which we have now described the chief characteristics, stands at the beginning of a series of much more complex and more obscure phenomena; it may therefore serve as the preparation and introduction to the study of these higher phenomena, among which we may mention the conceptions of delirium.