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I HAVE distinguished illusions as primarily representing transient misrepresentations of reality and as caused by some maladjustment of functions in the sense affected. This means that the sensational impression is more or less normal and is made in the sense affected by the illusion. Hallucinations are not always so regarded. Many of them involve a stimulus in one sense and an apparent perception by another sense. All of them represent a more fixed and organic tendency to false functional action. This is so true that we might define an illusion as a false judgment and hallucination as a false fact, except that we should need to alter our ordinary conception of both judgment and fact to treat such a definition as accurate. It suffices, however, to call attention to a marked distinction between them. The primary fault for the error in hallucination is not the judgment, but the false or erroneous sensory action. But there is one characteristic of hallucination which distinguishes it clearly from intellectual errors, and this is its nature as sensory action, which represents an apparent reality while the interpreting function may remain perfectly normal.
The definition of hallucination is often paradoxical. Parish, after quoting Edmund Gurney, who said, "Every psychological phenomenon that takes the character of a sense-perception is a sense-perception," remarked: "A hallucination is then a sense-perception like any other," and adds the statement of Prof. James, "only there happens to be no object there, that is the whole difference." The difficulty of such a definition is that it cannot serve any but a provisional purpose. There is certainly a very striking resemblance between normal sensations and hallucinations, but there is also a most essential distinction. Sensation does not stand for any arbitrary or abnormal phenomenon. It does not merely represent a subjective affection of the sensorium abstracted from its appropriate stimulus or cause. Abstracting from its cause it is, of course, subjective, but in all normal psychology and in most scientific parlance it intends to obtain its accurate definition and so distinction from false experiences by its implication of an external and determinate stimulus. An hallucination accurately conceived must also be defined to distinguish it from normal sensations, whatever its resemblances to it. A sensation in ordinary psychology and philosophy stands for a subjective experience determinately related to its appropriate stimulus, as color to light, sound to aural vibration, touch to hardness, etc. The perception or judgment associated with it can be tested in various ways, and some other quality than the one perceived at first will usually be discovered. It is not so with hallucinations. It is true that "only there happens to be no object there, that is the whole difference," but this difference is very great, and is not to be suppressed by an "only." The hallucination may be exactly like the sensation in its subjection nature, but it is quite different in its causal relations, and that fact constitutes a difference of considerable magnitude. An important factor in definition of it is that its cause or stimulus is usually not determinately related to its occurrence, as is a normal sensation. The usual stimulus is what may be called a
secondary stimulus, which means that it is not coordinated with a cause like that of normal sensation.
An important distinction between illusion and hallucination is the fact that the correction of an illusion tends to make it disappear, while the discovery that an experience is an hallucination does not remove its occurrence. This means that judgment has more to do with illusions than hallucinations. It is quite natural that the judgment should assign reality to hallucinatory phenomena, but when the judgment is found to be wrong the fact does not correct the hallucination. In illusion the correction of the illusion is the correction of the judgment. This holds true more or less in the organic illusions, which, though they may continue to occur, do not deceive our minds as to the apparent reality. There is nevertheless a resemblance even here between illusions of the organic type and hallucinations. The latter tend to occur as before their correction, but are definitely related to the sensation produced and are closely allied to normal sense-perception. But in general the correction of an illusion modifies the apparent experience and even removes its influence on the judgment. The sense of apparent reality is less noticeable than in hallucinations, where the phenomena undergo no alteration as sensory appearances when we become conscious of their hallucinatory character.
I may then define an hallucination as a functional sensory reaction imitative of those sensations which are correctly correlated with an external object. This is a broad definition to include all types of the phenomena, and designs to represent both its purely subjective character and its semblance to normal sensation. The most important characteristic, however, is what is called its subjective nature. At one time this conception of it assumed that it was a spontaneous production of the mind, but later investigation has shown that hallucinations have stimuli or causes as do normal sensations, but they do not have the same normal cause. They represent abnormal and non-correlated experiences in relation to stimuli. This is to say that the reality which gives rise to them may not in any sense be as like the cause of normal sensation as the object of
sense-perception is supposed to be like what it appears to be. In normal sense-perception we have a definite and intelligible relation between object and perception, whether the sensation be regarded as representative or not. But in hallucination the experience is not representative of the cause, even when the sensation is supposed in normal perception to be representative. The relation between stimulus and hallucination is an abnormal one, or the hallucination cannot be taken as an index of the supposed external object or cause.
Before illustrating hallucinations their divisions should be indicated. The psychic researcher has divided them into
veridical and subjective or falsidical. Veridical hallucinations are supposed to point to some such external cause as is apparently indicated in the experience, and so connects the phenomenon more or less with agencies like normal sensory stimuli at least in influence. Subjective or falsidical hallucinations are supposed not to indicate their cause in any definite manner, but to be as "unreal" as dreams and the products of the imagination. For certain purposes this division is very useful, but I think it should be subordinated to a more fundamental classification based upon the principles that distinguish between external and internal stimuli or causes.
I therefore think it better to divide hallucinations into those extra-organically initiated and those intraorganically initiated, or briefly,
extra-organic and intra-organic hallucinations. By this distinction I mean that some hallucinations are caused by stimuli occurring within the physical organism and some by stimuli occurring without this organism. We may further subdivide these, if we find occasion to do so. Of the externally or extra-organically initiated hallucinations we may distinguish the veridical and the falsidical, if there be reason to suppose any of them veridical. Whether or not the division may suit reality it indicates an alleged class of phenomena claiming scientific attention and supposed to lie between purely subjective hallucinations and normal sense-perception, at least in respect of their meaning. Intra-organic or internally initiated hallucinations will be subdivided according to their causes, all of them being falsidical, that is, non-indicative of the reality represented. They are all due to abnormal conditions, and possibly no clear line of classification can be made regarding different types of them. Perhaps one distinction may be useful, namely, that which distinguishes between hallucinations correlated with what we may call
primary stimuli as opposed to those correlated with secondary stimuli. Some hallucinations arise in the sense affected by the stimulus and others arise in a sense not affected by the stimulus. Thus the stimulus may be in the ear and the hallucination may be a visual phenomenon. This secondary stimulus may be either peripheral or central, that is, it may be either in some part of the bodily tissue or in some part of the nervous system. In addition to this it may be either organic or functional, that is, it may be some physical pressure or lesion, or it may be functional disturbance of some kind. There is no way to determine this except in the individual case. The utmost that we can do in classifying the instances is to indicate these various possible sources of stimuli giving rise to hallucinations. The general knowledge of the fact that stimuli of this kind produce them is all that is necessary to protect us against the interpretation of such phenomena as representing the realities which they appear to indicate. The point to make clear is that subjective hallucinations are abnormal phenomena, and that we require some criterion for distinguishing between those which have an internal origin and those which are initiated from without.
The primary point in the cause of hallucinations is their relation to stimulus and to normal perceptions. In normal experience we find a certain constant relation between stimulus and perception supposedly representative of the object causing the perception. Light affecting the retina elicits color, vibrations affecting the ear produce sound, physical objects affecting touch evoke the sense of resistance, and similarly with the other senses the object perceived is supposed to affect the sensorium which does the perceiving. It is quite different with hallucinations generally, and in fact it is this difference that serves as a fundamental criterion for determining when the experience is hallucinatory. The stimulus in such phenomena is not normally correlated with the sense apparently affected, but comes from some other part of the sensorium. Hence it is called a secondary stimulus. For example, a disturbance may occur in the auditory functions and the person may not hear sounds, but may see visible objects of some kind. An unusual stimulus may occur in the stomach, and we may have a nightmare. A headache may give rise to apparitions. In all these imaginary cases the relation between stimulus and sensation or apparent object is not like the normal order, and hence the stimulus is called secondary to indicate that, in respect of stimulus per se, the phenomenon resembles sensory experience, but in respect of the thing apparently perceived it is wholly different from the normal. With this explanation of the general cause of hallucinations we may proceed to some illustrations.
One of the most interesting hallucinations on record is that of Dr. Nicolai, of Berlin, who was able to record his experience and to observe it as carefully as he could observe facts in his other scientific work. I give it as quoted in the
Transactions of the Royal Society of Berlin.
"During the latter six months of the year 1790, I had endured griefs that most deeply affected me. Dr. Selle, who was accustomed to bleed me twice a year, had deemed it advisable to do so but once. On the 24th of February, 1791, after a sharp altercation, I suddenly perceived, at the distance of ten paces, a dead body, and inquired of my wife if she did not see it. My question alarmed her much, and she hastened to send for a doctor. The apparition lasted eight minutes. At four in the afternoon, the same vision reappeared. I was then alone. Much disturbed by it, I went to my wife's apartments. The vision followed me. When the first alarm subsided, I watched the phantoms, taking them for what they really were, - the results of indisposition. Full of this idea, I carefully examined them, endeavoring to trace by what association of ideas these forms were presented by my imagination. I could not, however, connect them with my occupations, my thoughts, my works. On the following day the figure of the corpse disappeared, but was replaced by a great many other figures, representing sometimes friends, but more generally strangers. None of my intimate friends were among these apparitions, which were almost exclusively composed of individuals inhabiting places more or less distant. I attempted to produce at will persons of my acquaintance, by an intense objectivity of their persons; but, although I could see two or three of them distinctly in my mind, I could not succeed in making exterior the interior perception, although I had before seen them afresh when not thinking of them. The disposition of my mind prevented me from confounding these false appearances with
reality."
After some treatment, according to the methods of the time, the apparitions disappeared. Their interest for us, however, is in the fact that the man who had them was physically well and healthy in so far as all indications went, and was a scientific observer of his experiences. Similar phenomena are often observed by physicians, but they take no account of them for the psychologist.
Dr. Boris Sidis mentioned an interesting case to me that represents very clearly the influence of determinate secondary stimuli. He had a case which represented apparitions of deceased persons. He examined the eyes and the retinas, only to find them perfectly sound. He then examined the cars and found them inflamed. He then resorted to an increase of the stimulus in hearing and found that he had increased the number of "spirits" visible When he decreased this stimulus, the number of "spirits" correspondingly decreased, showing in each case that the visions were due to the influence of disturbance in the auditory centres, and that this influence made itself apparent in phenomena associated with the healthy part of the neural organism. The apparitions were not only not real, but they were not even instigated by any stimulus on the
sensorium apparently affected.
The same author narrates an instance of nosebleed which resulted in causing everything in the field of vision to appear red. This sensation of red was also excited by a pain in the head. On another occasion the same subject had sensations of red and of pain in connection with a dream of suicide.
Dreams and deliria also illustrate hallucinations in a clear form. The specific causes are not always determinable, but the result is the same as in persistent hallucination. Only one peculiarity separates dreams from persistent hallucinations. It is the fact that they are only transient as the state of sleep. Deliria represent abnormal conditions, physical or
mental, but may accompany only a transient illness. But in both the mental machinery involved is the same as in ordinary hallucinations.
As an illustration of dream hallucination, take the case of the man who dreamed that he was walking on ice in the Arctic regions, and awakened to find that his feet were exposed outside the bedclothes. Here was a secondary stimulus with distinct tactual sensations of cold and perhaps visual appearances.
I have two dreams in my own experience which illustrate the fact very clearly, and this 'because I awakened while dreaming, and the images of what I was dreaming about still lingered as hypnogogic illusions, apparent sensory realities, for some time. In the first I saw a mountain lake with cottages on its shores, and I was standing on an elevation looking down on the scene. This vision, after-waking, lasted for, perhaps, ten seconds or more. It disappeared suddenly after I noticed crevices breaking in the rocks on which I was standing. In the second I was in my old room at my home in Ohio, and noticed the walls with a paper on them that was never on the actual wall in my experience. This apparition vanished and I discovered that I was in my bed in New York. I was wide awake when this occurred, having awakened in the dream, and continued seeing the walls in a puzzled condition, as I did not know where I was until the apparition vanished.
In both these cases I was able to note that I was apparently looking at real objects, the normal consciousness and its observation confirming what we infer from the vividness of our dream visions, namely, the sensory action of the mind as in reality. This explains why we take the visions as real, as the same feeling accompanies ordinary hallucinations. The same is true in deliria which occur on the borderline between normal consciousness and conditions in which the deliria are not remembered. I remember one of these cases in an attack of intermittent fever, when I saw the wall of the room cracking and threatening to fall. I was told what the other facts in the delirium had been. This one I remembered at the time and called attention to it. It was distinctly real to me. The vision had all the qualities, external appearance, of reality except the tactual confirmation.
Hallucinations can also be produced by hypnotic suggestion. The peculiarity of this fact is that they occur with perfectly healthy subjects. It is perhaps admitted by all experimenters who understand psychology that hallucination is the normal form of suggested matters. The manner of the subject indicates this, and his whole conduct toward what is suggested. The best evidence, however, of sensory effects like hallucinations will be found in those states in which the subject remembers what he had been told that he will see, hear, or feel. I remember one instance in which the hypnotic subject remembered what the suggestions were after he came out of hypnosis. The operator (not professional) suggested on one occasion that he saw certain wild animals, such as the lion, tiger, elephant, etc., and the suggestion was accompanied by remarks calculated to awaken fear of the animals. This was manifested. After he was awakened another request was made to try hypnosis a second time. He refused, saying that he did not want to go where he could see those wild animals, and on being asked to describe what he saw, he did so in just such terms as a normally conscious person would describe real objects of the kind. There are no doubt other similar cases on record, and I wish here only to give a clear illustration of the effect of hypnosis and suggestion in eliciting hallucinatory images and arousing exactly the same mental and other machinery that is active in morbid hallucinations.
An interesting phenomenon in connection with hypnotic suggestion is what the psychologist calls
negative hallucinations. Such as I have described are called positive hallucinations, and mean that an object which does not really exist can be made to appear to exist. But in a negative hallucination an object which does actually exist before sense-perception can be made to disappear at suggestion. I may be looking at a tree, and if told that I cannot see it I will not see it, and as long as the suggestion operates I cannot be made to see it. This experiment has been performed myriads of times, and is the complementary phenomenon of positive hallucination.
These illustrate sufficiently the different types of hallucination, and we have now to look at two aspects of them as mental phenomena. The first is their
causes and the second is their meaning for the psychologist. Their causes have been briefly indicated in their classification and in the distinction between sensations produced by primary stimuli and hallucinations produced by both primary and secondary stimuli. But nothing has been indicated regarding their meaning for psychology and its larger conceptions of mental phenomena and their implications.
In general the primary cause of hallucinations is some morbid condition of the organism. This holds good even when the stimulus is external and normally related to the sense affected. Normal experience represents stimuli and sense-reaction properly connected, as in touch, sight, hearing, smell, etc. The cause of the sensation is definitely correlated with its effect, and that relation is so constant and regular that we can easily ascertain why and how any particular mental experience occurs. But if any morbid condition of the organism occurs, the stimuli, internal or external, are distorted, and the effect is not representative of the cause. That is, we cannot use the normal standards for estimating or determining what the cause of the experience is. In hallucinations we cannot infer from the sensation of color that it is caused by light on the retina. We cannot infer from odors that the cause is the ordinary stimulus of the olfactory nerve. We have to seek the cause elsewhere. Most frequently it is in the organism, and is some abnormal condition either of the peripheral or of the central system, whether organic or functional in either case. For example, pressure on a nerve by inflammation or organic growth may give rise to hallucinations. An ulcer in the brain may do the same. Any stimulus due to disease may produce them in abundance. Most frequently perhaps they are found in general disturbances, so general that they could not be made intelligible without the quotation of long cases and examples. But speaking of all "fallacious perception," including illusions and hallucinations, but more particularly the latter, and of both external and internal stimuli, Parish summarizes the whole matter in the following
statements:
"The dependence of hallucinations on external stimuli is well illustrated in the following
often quoted communication from a patient:
"'Every tree which I approach, even in windless weather, seems to whisper and utter words and sentences. The carts and carriages rattle and sound in a mysterious way and creak out anecdotes. The swine grunt names and stories, and exclaim in surprise. The voices of the dogs, cocks, and hens seem to scold and reproach me, and even the geese cackle quotations.'
"To this class belong also hallucinations occurring in clouding of the cornea or lens. Perhaps the case quoted by Griesinger of the man who always saw a black goat at his side may be taken as an example. In the same way eyelashes, tears, and such like may
furnish the material for hallucinations. This is specially likely to occur, as has often been insisted, if there is any want of distinctness in the original impression. Myopia and other defects of vision which cause the sense-impression to be indistinct also predispose to fallacious perception. Zander reports that among 100 mental cases he had eight color-blind patients who all suffered from visual delusions. Leubuscher's account of the patient who mistook himself for his mistress seems to point to the same explanation, for if he saw himself in a mirror he knew his face to be his own, but if he only saw his reflection dimly in the window-pane, he took it for the image of his lady.
"The stimulus, however, need not be an objective sensory impression; it may consist in pathological or physiological irritation of the sensory centres. In the normal state both processes, as we see, are recognized as so-called sensations; but if dissociation obtains, they may become causes of false perception.
"The physiological sensory irritation may depend on changes such as metabolic processes in the centres themselves, and in the nerve-tracts leading to them. The pathological irritation may depend on morbid processes, such as meningitis, which radiate from neighboring parts of the brain; at least, cases of sensory delusion in which external impressions fail to be perceived, either owing to peripheral disturbance or because the ascending current is broken off at some intermediate point, are most easily explained by supposing an irradiation proceeding from the morbid part. Or, secondly, the pathological irritation may act from some given point in the course of the sensory path concerned; for instance, in a partly atrophied nerve the seat of excitation would be the point of transition from the morbid to the sound parts. Such cases might plausibly be explained by adopting H. E. Richter's view of hallucination as an instance of anomalous functioning of the sensorial nervous system analogous to anaesthesia dolorosa, in which, though the peripheral stimulus cannot reach the central organ, owing to the irritation of the sensory nerve at some intermediate point, the brain nevertheless receives impressions from the seat of the
irritation."
The whole system of influences instigating hallucinations is indicated in this passage, and may be summarized in the irradiation of stimuli from the natural centre of their influence. We should naturally suppose that a lesion or organic disturbance in the auditory centres would affect the machinery of hearing, and so it does. But it does not always cause hallucinations of hearing. It may affect vision, as we have seen, and this fact is explicable by the irradiation of the influences associated with the disturbance to associated centres of action. In most cases this influence is intra-organic, and associated with insanity or abnormal conditions, physiological or psychological. The hallucination will not necessarily be a symptom of insanity, but only of some disturbance in the nervous system or its functions. That disturbance may be very slight, and it will be symptomatic of serious conditions only when it extends its agency over the mental life, or persists in a manner to show that it is due to more fixed influences than those which produce illusions, dreams, deliria, or hypnotic hallucinations.
It is not my purpose to go into any details regarding the causes of hallucinations, nor to discuss any theory of them in general. That is the work of the student of psychiatry or abnormal psychology. It will suffice here to recognize the fact that they have some abnormal cause in the organism in most instances, and then to examine the meaning of such a fact for the student of psychology and the general public which indulges theories of apparently supernormal phenomena without any clear knowledge of the difficulties attending their speculations. The classification of hallucinations implied the different types of causes, and I may return to this as a means of separating the various problems confronting the student of abnormal and supernormal psychology.
The reader will remember that I divided hallucinations into those that are intra-organically initiated and those that may be extra-organically initiated. The intra-organic may have peripheral or central stimuli. The peripheral stimuli will represent either the primary or secondary influences. The primary stimuli will be some affection of the organism which perceives the apparent object. The secondary stimuli will be some affection whose influence irradiates to some other sensory centre than the one we should most naturally expect to be concerned. Central stimuli may be similarly divided. The primary will be an affection of the central function concerned, and the secondary will be influence irradiated from one centre to another, and both will represent psychical function of some kind as distinct from the bodily affection of peripheral stimuli. In all of them, however, both peripheral and central, the hallucination or sensory product will not involve a representative percept as in normal experience, but will be a subjective result of the mind's own making. In other words, the hallucination will be falsidical, which is to say, that it does not represent the cause of itself in terms by which our normal action and behavior are directed. The phenomena are no better than the products of imagination, in so far as reality is concerned.
It is not so easy to divide extra-organic hallucinations, as we are not so sure that we can assume different stimuli corresponding to their types. Neither can we assume without evidence that the stimuli, when. we suppose a distinction in kind between the hallucinations, can be divided as are those of intra-organic cases. We may, however, distinguish the hallucinations provisionally into what are known as apparitions or ghosts, and those of an irregular character which are related to external physical stimuli. Of course, many of the class of apparitions belong either to illusions suggested by external stimuli or to hallucinations of disease intra-organically initiated. But
I am here referring to that class of apparitions which psychic researchers regard as veridical, and which do not show the ordinary character of illusion or of hallucinations physically initiated. Many psychic researchers would remonstrate that they are not hallucinations of any kind, but representative realities, and I shall not unqualifiedly deny that contention. I can only postpone for the moment the consideration of their nature, while I accept the actual conception which the student of abnormal psychology has of them without investigating them carefully. I call them hallucinations in deference to that point of view for the sake of ascertaining their causes before pronouncing on their possibly real character. When this is effected we may find that we can also apply here the distinction between peripheral and central stimuli. But as this involves speculative considerations, which are as yet wholly undetermined and which may never be true, I think it best to distinguish them provisionally from those hallucinations determined by ordinary external stimuli, and so recognize a possible type determined by some extraordinary stimulus. I may therefore divide extra-organic hallucinations into those which are sensibly or physically initiated and those which are supersensibly or superphysically initiated. Whether the last class really exists is not now the question, as I am concerned partly with a question of definition and partly with an alleged claim whose integrity has to be examined.
The last remark and the fact that hallucinations sensibly or physically initiated are like the intra-organic type, namely, falsidical, suggest that it might be well to classify them from their characteristics rather than their causes, and then study them for their causes. A special reason for this view of the case is the fact that there is no essential difference between hallucinations determined sensibly by external or extra-organic stimuli and hallucinations determined by intra-organic stimuli, especially of the peripheral type. They are both falsidical, which is to say that they are not representative of their causes as are normal sensations, at least as these are supposed to be in our common conceptions. With the distinction, therefore, between veridical and falsidical types, we may discuss the question whether there is adequate reason for the distinction, and whether the veridical type can have any such cause as is claimed for them. It is agreed that ordinary hallucinations are not representative of their stimuli, and in fact this conception is the reason for calling them hallucinations, and only since the psychic researcher came to recognize a possibly transcendental meaning for apparitions have we heard of the distinction between veridical and falsidical hallucinations, meaning thereby that possibly one type stands for the reality of discarnate spirits. The opposing view maintains that they are all equally subjective creations. They have their causes, but these causes are not what they are taken to be by the subject of them.
The issue between the two schools of thought is clearly defined. The psychiatrist or student of abnormal psychology classifies apparitions with subjective hallucinations, and in fact is content with calling them hallucinations without qualifying them as subjective, as he regards all such experiences as subjective without distinction. His most radical opponent insists that apparitions occurring under certain circumstances are not subjective phenomena, but representative of the reality of that which they appear to be. In other words, he thinks apparitions of a certain type and occurring under given circumstances are really discarnate spirits, and hence he refuses them the character of hallucinations of any kind. This is at least the naive view of such experiences.
There are three types of apparitions which give rise to the distinction between veridical and falsidical. They are apparitions of the living, apparitions of the dying, and apparitions of the dead. Some of these are certainly explicable by ordinary causes and are to be treated as subjective or falsidical. But those which occur coincidentally with events at a distance and are not known by the subject of the experience, if they occur in sufficient numbers to compel the view that they are not due to chance, suggest some unusual cause. In the collections of the
Phantasms of the Living and of the Proceedings of the Society for Psychical Research the numbers seem great enough to exclude the application of chance coincidence, whatever the final explanation of them, and this fact has induced the final explanation of them as veridical, which means at least that they are in some way related to a definite and representative cause. But if so, why call them hallucinations of any kind? One school calls them this because it wishes to have them regarded as subjective and unreal, the other wishes to regard them as representative of reality.
The position which I wish to take in the case is one that is intermediate between the two schools. Whether this was meant by those who originally distinguished between veridical and falsidical hallucinations I have no means of deciding clearly. I imagine that it was, as there would have been no good reason for describing them as hallucinations while regarding them as veridical, unless it was meant to mediate between two points of view. But whether the position which
I wish to take in this discussion has been anticipated by others or not, it is one in which I wish to maintain the possibility that apparitions may be hallucinations in their representative character and yet correlated with just such a cause as they most naturally suggest. This is to concede one point to abnormal psychology and to deny it another in its views of the phenomena.
I shall not here undertake to prove that veridical apparitions are either supernormal facts or indicative of the causes which they at least superficially suggest. That would require a large collection of facts and a discussion as lengthy as the labors which I have quoted above. I shall merely try to show from what we know of normal and abnormal psychology and from the phenomena of ordinary and subjective hallucinations that this is possible, and hence we may leave to the future the collection of the evidence to prove it a fact. I shall therefore begin first with the general meaning of hallucinations and proceed from this to an examination of their causes.
The first general meaning of hallucinations is the fact that they attest the subjective activity of the organism or of the mind in the production of apparent reality. We found that even in normal
sense-perception we had to admit or suppose that the organism or mind was a factor in its perceptions. Color, sound, odor, temperature, etc., were not representative of the stimuli even in normal sensations. The mind's reactions partook of the nature of its own action, as any physical object will react against impact according to its own inner structure and does not represent the merely transmitted energy of the object affecting it. A bell was the illustration of this law. The bell produces a sound according to its own nature rather than according to the sole nature of its cause or impact upon it. This being the law of physical phenomena, we must not be surprised at its occurrence in organic beings. So it is clearly illustrated in sensation and mental reactions, which are not supposed to represent the nature of external causes, or to be constituted by them. Hallucinations are particular proof of this view, and they serve as this evidence with special force because the argument holds good on the supposition that normal
sense-perception is representative. No matter how firmly "common sense" way adhere to the conviction that objects in the external world are exactly as they appear, it cannot maintain for a moment that the apparent objects in hallucinations are correspondent or representative of the apparent reality. It is precisely because we discover that they do not represent what we experience in normal perception that we distinguish them as hallucinations and imply that the cause of them is not there as in normal sensations. Similar phenomena occur even in normal experience, such as phosphenes when pressure is exerted on the eyeballs, or "seeing stars" when a blow on the head occurs. In hallucination of all types as recognized by psychiatry this disparity between stimulus and reaction or sensory product is the marked feature of the phenomena, and we feel compelled to regard the effect as a subjective product, whatever its cause. We do not dream of assigning it objective reality, at least in any such form or matter as we ascribe to normal stimuli.
The consequence is that we reinforce the doctrine that the mind is a primary factor in the nature of its experiences. Whatever doubt about such a view may be maintained in normal experience, we can have no doubt about its capacity in the abnormal to reproduce a simulation of reality in its hallucinations, and the same conclusion is sustained by dreams and deliria. When we find that normal experience also has its subjective aspect the result seems still more conclusive, and the subjective nature of mental products, even with any theory of their causes, seems so well secured that no question of it as a fact can be raised. We find a point at which the phenomena of hallucinations and normal experience unite, and this is the subjective action of the mind in the production of its phenomena. The only difference between the normal and the hallucinatory facts is their different relation to stimulus. Neither are supposed to
represent reality, but only to indicate it, the one showing a definite and regular relation to certain stimuli and the other an apparently accidental and irregular one. But in the actual appearance of the reality as presented to consciousness there is no constitutive or internal difference. Consequently with the assumption that even in all normal experience the sensations are subjective facts and not representative of the cause, we have this idea more emphatically indicated in hallucinations, and it enables us to say that the fact apparent in the hallucination is not real. Hence the implication in our ability to say that apparitions are hallucinations is that they do not stand for any such reality as normal experience would indicate.
The defendant of the "reality" of apparitions or of the external facts which they are supposed to indicate will have to admit the cogency of this contention. Hallucinations, whatever their causes, are such subjective phenomena that the classification of any fact with them must carry with it the implication that no such reality is indicated as is superficially apparent, and this suffices to exorcise "spirits" in the case, if we are obliged to use as our criterion of reality the standards of normal experience, as reflected in the ideas of "common sense" or representative perception.
But without disputing this general view of the case, there are certain important facts which even psychiatry will have to admit, and which may indicate that its standard of judgment in such matters is precisely the representative one which its own doctrine of hallucinations claims to reject. If it concludes that hallucinations do not represent reality, it does so on the ground that normal experience does this in some sense. But with the fact that normal experience is quite as subjective as the abnormal and is yet indicative of external reality in its own assumptions, the student may return to the principle of normal experience and ask if that may not be applicable also to the abnormal, especially as there is similarity of kind in the two types of phenomena and as the admission must be made that hallucinations have stimuli external to the centres of reaction. This is simply to say that we cannot assume the naive standards of normal sense-perception as valid representatively for determining the subjective nature of hallucinations, and then turn around to admit the subjective nature of sense-phenomena while we admit them to be indicative of a non-representative cause, without having to face the possibility that hallucinations may be indicative of external causes when they are not representative of them. We may simply press the fact that in normal experience the determination of reality is not effected by any representative relation between stimulus and sensation, but by the uniformity of certain causal relations which are supposed to involve externality without indicating its nature. With that in view we may be able to reconstruct the meaning of hallucinations.
The older meaning of hallucinations was that they were wholly subjective affairs, and they were even regarded as spontaneous productions of the mind, as opposed to externally produced normal sensations. This naive view has been greatly changed, and they are now regarded as subject to the law of causation in much the same way as normal experience. Before applying this to apparitions it will be well to examine the general explanation of hallucinations which relates them as closely to normal sensations as their other characteristics distinguishes them from these. If apparitions are to be classified with hallucinations generally, and especially, of the purely subjective type, we must expect them to accord with the same laws of causality. On the other hand, if hallucinations show certain definite relations to external causes, we may have reason to press this resemblance to normal experience as a significant fact in support of a view not at first suggested by them. I shall therefore summarize the principles and implications involved in subjective hallucinations as a qualification of that import which psychiatry has so long assigned them. I shall then take up the special case of apparitions and see how the doctrine may apply to them.
1. In the views of abnormal psychology the universal doctrine seems to be that hallucinations are, in some sense of the term, "externally" initiated or caused. The externality may be nothing more than foreign to the nervous centre reacting to produce them. But they are no longer held to be spontaneous Phenomena. They are related to causes precisely as normal experience is related, with the exception that the relation is not a normal one. Of course this "external" or extra-organic initiation is more apparent in the case of hallucinations instigated by peripheral and external stimuli, and the hallucination is due to abnormal conditions of the sensorium affected. The relation to normal experience is here fairly close. But the "external" initiation is no less true of the purely subjective hallucinations. This is unquestionable in the case of peripheral instances due to lesions or morbid conditions in the bodily tissue. The psychiatrist also believes, and in many instances he has the proof, that hallucinations centrally instigated, or produced by morbid psychical functions, are no less subject to causation that is "external" in the widest sense. The consequence is that, while we admit in hallucinations a difference in relation to reality as supposed by normal experience and a representative theory of perception, we assume that the same law of causality applies to them as to normal experience, namely, that they have an "external" cause, even though that "externality" be nothing more than foreign to the centres concerned- Some of them, as we have seen, have a true external cause, and all of them differ from normal sensations only in a correlation with that cause which is at least less representative of its nature than in normal experience. We conceive a certain relation between a blow on the head and the tactual sensation, but when it results in "seeing stars," we do not conceive that the relation between the "stars" and their cause is the same intimate or supposedly representative one that we conceive in the sensation responding to the blow. This is the whole difference between normal sensations and hallucinations. The external cause is there, but it is not so related to the effect that we can perceive it in the same way that it is perceived in normal instances.
2. In normal experience the determination of causes of sensation is dependent on the directness or immediacy of the connection between certain facts and the uniformity of that connection in different individuals. It is not in the likeness of the object perceived to the sensation produced. That sensations are representative of the object is not assumed for a moment. The antithesis, if we may so speak, between sensation and cause may be as great as between hallucinations and their causes. The primary question is the uniformity of the coexistence and sequence in certain facts and their universality or multiplication in human experience generally. The cause in such cases means the fact which we have experienced as the antecedent or associate of the effect or event to be accounted for, and what we can expect to find when its presence is conjectured. In hallucinations this normal experience has not taught us to expect any particular cause either for the individual or for the race. If we could get any such uniformity of connection between hallucinations and their particular causes, we might form a different conception both of them and their associated facts. But it is the capricious and ununiform relations that prevent us in most cases from attaching the same kind of meaning to their occurrence that we assign to the connections of normal sensations. But if we did find a certain fixed connection between subjective experiences and certain definite external events, we should be justified in supposing something like the causes which we assume in normal phenomena. But this uniformity would have to extend to like relations in different individuals, in order to exclude purely subjective influences.
3. In some cases we do find a certain uniformity between the hallucination and its cause. Often in fainting fits the subject sees a certain apparition; it may be a light, a human form, or any arbitrary object whatever. A similar phenomenon is often noticeable with epileptics. Others, at times of physical exhaustion, see certain types of apparitions. But two facts are noticeable in these phenomena. First, the apparent object is not such as can be tested by the other senses. Secondly, the same apparition is not perceptible by others under like morbid conditions. It is these facts which force on us the view that the phenomena are subjective productions. The cases are intra-organic, whether the stimulus be external or internal. Hence, though we find certain uniformities of
coexistence and sequence in hallucinations supposed, they are not of the character to justify the assumption of a foreign reality of any particular type. The utmost that could be conjectured was that something foreign had affected the organism. We should have to discover certain uniformities of extra-organic stimuli and subjective experiences in which some identity of meaning could be observed before we could ascribe an objective meaning resembling normal experience to the subjective phenomena. When the hallucination is due to intra-organic stimuli there can be no assumption of external realities either like or unlike the apparent object of perception. We must have hallucinations related to extra-organic stimuli, and so related that their uniformity with the individual or a multiple of individuals will justify the conjecture in favor of a special type of cause or stimulus.
4. Now apparitions of the veridical type seem to conform to this very condition of external causality
inferable from the circumstances. Those apparitions not correlated with any special event external to the organism in which they occur are of course intra-organic and subjective. But what we call veridical apparitions are so related to an objective and external event, namely, purely extra-organic causes, that they seem to conform to the standards by which we determine external reality in normal experience. It is not the fact that the apparitions represent human forms, living or dead, that makes them interesting, but the fact that they coincide with certain events not known to the percipient of them. This circumstance cannot be forgotten. It is the crucial circumstance in the whole question. Of course if such phenomena occurred in such a way to suggest chance coincidence the matter might be quite different. But their grouping about an event occurring at the time and outside the knowledge of the subject of them is the important fact to be accounted for, and not the form in which the experience takes. Hence it is not the fact of an apparition that creates curiosity, but its coincidence with the event which the apparition seems to indicate. It is this coincidence that requires explanation. That coincidence is found in most cases to be with some friend's thoughts or experimental effort to produce an apparition of himself, or with a serious illness, or very frequently with the fact of death or dying. If such phenomena, measured against similar occurrences which do not indicate coincidence of any kind, were explicable by chance, we should not feel any temptation to treat them more seriously. But if reports of them be true, comparatively few occur in which a coincidence of some kind cannot be detected, and it seems that the coincidental instances are so frequent, related as they are to certain critical conditions in the life or thoughts of the perceived person, that chance does not appear to be their proper explanation. There is often, or perhaps usually, just enough indication in the experience or apparition to point definitely to the person or events concerned, and the causal relation seems as well substantiated as any instance of such causal relation traceable to intra-organic stimuli when the hallucination is supposedly subjective. With the proof that chance coincidence does not explain the occurrence of the apparition and that the events which must be assumed to be the causal agent are not intra-organic, we are placed in a situation where we must choose between considering apparitions an exceptional type of hallucination, if hallucinations they be, and their reality after the conception of the naive mind.
I shall not here attempt to give the evidence that there are such apparitions involving an external cause, as so often claimed, because I am concerned only with its possibility until more evidence can be collected. But it may be worth mentioning that the records already made by the Society for Psychical Research show such formidable suggestions of such an explanation that the matter will have to be considered from that point of view. The investigators did emphatically assert that the calculation proved they were not due to chance. They did not attempt to offer a positive explanation, telepathic or otherwise, leaving this matter to the individual student. If not due to chance and if due to external causes, whether the thoughts of living or deceased persons, they point to causes which have to be treated quite differently from the usual causes recognized in psychiatry. The only question that will remain is whether we shall still speak and think of apparitions as hallucinations, even when qualified as veridical.
5. If apparitions are instigated by the causes which they apparently indicate, the stimulus is certainly a very delicate one, and represents an unusual process. There are two things to establish in this question. The first is that delicate stimuli can produce hallucinations, and second that apparitions may be regarded as hallucinatory without making them purely subjective in their causation or meaning. The same facts will bear upon the solution of both problems.
That very delicate stimuli will result in hallucinations is a part of the fundamental conceptions of psychiatry. In normal sense-perception the stimuli seem to be coarser, so to speak, than those which excite similar products subjectively in the phenomena of hallucinations. Irradiation in secondary stimuli represents very delicate agencies. They are not effective in ordinary conditions, and often represent influences on the organism that lie below the threshold of consciousness; that is, that are not intense enough to produce an effect on the normal sensorium.
Still better illustrations of this delicacy is the fact that the state of mind will give rise to illusions and hallucinations. I have already called attention to the circumstance that mental preoccupation will distort a sensory impression so as to change its appearance. The illustration of reading words wrongly is an instance. The state of the mind produces an apparent reality which is not represented by the stimulus at all. In the more morbid forms of mental influence this is still more striking. The mind may be so intensely occupied as to wholly ignore its sensations and apparently see objects that represent nothing but its thoughts and expectations. It is very common among the insane, and can be produced, as indicated above, by hypnotic suggestion. In such instances mere thoughts give rise to apparent realities. This is probably the case in dreams. This means that mere mental states can produce on the sensorium the effect of actual sensory stimuli. With this once granted, it is only a question of evidence whether similar extra-organic stimuli might not produce the same result. Such illustrations as I have given are of the intra-organic type, and we should only have to obtain evidence of telepathy to extend the same possibilities to the extra-organic stimuli having the character of mental states.
Before taking up this question of extra-organic mental stimuli, I must call attention to another type of mental influence on hallucinations. I refer to the transmission of causal influence from subconscious states to the normal consciousness. This may be illustrated in the phenomena of crystal visions, where latent memories are evoked in such a manner as to appear as sensory realities. But the most important type of these mental stimuli eliciting hallucination and involving transmission of influence from subconscious to conscious action is illustrated in cases of secondary personality, where the subliminal action seems to deliberately influence the normal consciousness to see realities when they are not actually present. The best instance of this is the case related by Dr. Morton Prince.
This case to which I refer is a remarkable one of multiple personality. I cannot here undertake to explain it fully for the lay reader. The chapter on secondary personality will explain it sufficiently. All that we need to know at present is that our minds are capable of subconscious action not known or remembered by our normal stream of consciousness, and so may simulate the action of an independent person. Many think that this subconscious action is another person, but there is no excuse in this day for this belief, natural as it may be for those who measure their own personality by that of which they are conscious. The one thing that distinguishes the two or more personalities in all of us is the fact that the memory connection between these different streams or groups of mental states is severed. One set of ideas is dissociated from others, and the normally conscious states are especially dissociated from the subconscious ones. They may interact and produce effects on each other, but not of the kind involving any memory of the fact, or any consciousness of it, or conscious voluntary relation to the effect. With this preliminary account of what we mean by secondary or multiple personality, we are prepared to understand the following facts in the remarkable case of Dr. Prince.
It was one of several personalities, but my purposes here require me to take account of only two of them. One of them, which I may call A, was a mischievous, impish little witch, if I may so describe her, full of tricks and jokes which she would play on another personality, which I shall call B. The interesting point here, however, is that A was able to induce hallucinations in B. For certain purposes A, who did not like the other personality, would induce all sorts of hallucinations in B, such as spiders, toads, sensations of cold, absence of limbs, etc. This means that the subconscious personality was able to produce in the surface consciousness the appearance of physical objects, and so illustrates in a peculiar form the fact that mere mental states can give rise to hallucinatory phenomena; a fact, of course, sufficiently well known in insanity, but not so clearly shown there as in the intelligent and deliberate efforts of A to influence B in the case before us. This A would describe afterward in automatic writing what she had done and why she had done it. The story must be read to be appreciated, and I can only emphasize here the fact that one state of consciousness not introspectively known to another could induce an hallucination which was cognizable by the other. The fact illustrates an indirect mode of communication between two streams or groups of mental states, and the capacity of producing apparently real effects or objects there.
All these illustrations of delicate causes of hallucination are intra-organic. It remains to show that similar extra-organic stimuli can produce like effects. With the phenomena of hyperaesthesia we ought not to think it impossible. Moreover, with such experiments as Lehman and Hansen performed, in which unconscious "whispering" or involuntary sounds produced by merely thinking of objects had the effect of sensations on a percipient, in which there was no consciousness of the stimuli, we may well imagine what may be possible in hyperaesthesia. There is no hard and fast line between what may be produced by intra-organic stimuli of a delicate character and extra-organic stimuli of a like nature. Let us see whether there is any evidence of such phenomena.
6. The phenomena of telepathy exhibits the influence of delicate extra-organic stimuli. I cannot here undertake to show that what is called telepathy is a fact, but must refer readers to the data in the
Proceedings of the Society for Psychical Research for this conclusion. I can only indicate what I mean by the term. To me it denotes nothing more than a coincidence between two persons' thoughts which requires a causal explanation. By this
I mean, of course, that the phenomena educed in its support are not explicable by chance coincidence, but show some causal nexus which has yet to be determined in its mode of action. Whatever that mode of action, the phenomena exhibit the supernormal influence of one mind upon another in a manner not explicable by the ordinary agencies of sense. In some way the thoughts of one person make themselves known to the mind of another. The fact is very rare, and is much more rare than the general public supposes. But it occurs often enough for us to suppose that extra-organic stimuli of the nature of mental states can produce effects on the minds of others. The only question that remains is, whether these effects ever take the form of hallucinations.
There has not been as careful observation in most of the experiments illustrating telepathy as there should have been for the mental states of the percipient. Apparently in most instances the thoughts of the agent were obtained by the percipient without any hallucinatory tendencies, as no report on this matter was made. But in certain cases where the imagination and memory of the percipient were participants in the results, which still contained enough identity with the thought or drawing of the agent to prove coincidence, there is trace of hallucinatory influences. In one set of experiments which I myself performed there were very clear evidences of hallucinatory effects. The subject described what he saw, saying that he saw many geometrical figures floating before his vision and that he picked out the most vivid instances. These turned out in each case to be the correct ones. In a spontaneous instance a man was smoking a cigarette and suddenly saw a phantasm of his brother's face with the hand on the side of his head, the skull having been crushed in. In a moment the door-bell rang, and a reporter said that the percipient's brother had had his skull fractured on the side of the head. Inquiry at once over the telephone at the newspaper office confirmed the facts, but it was said that he was not so badly hurt as at first supposed. Knowing where the brother was to be at that hour, inquiry was made over the telephone at this place, and the brother responded to say that he was well and having a good time, no accident of the kind having occurred. It was a case of mistaken identity in the newspaper office. The important point is that the percipient had an apparition of his brother, though the reporter's mind probably did not have a visual picture of the brother before it. The thought of the reporter appeared as a physical object, and as a remembered object in the experience of the percipient. That the phenomenon was hallucinatory there can be no doubt, though it was veridical and not merely subjective. The incident, of course, is not evidence of telepathy as we should like to have it, but that phenomenon once proved, we can readily accept this instance, which came to me from a perfectly reliable source, as illustration of the claims in question. Another instance which I have on record shows hallucinatory effects of telepathy at great distances. The percipient saw apparitions of the agent's thoughts, that is, apparitions of the objects he was thinking about.
But if experimental phenomena are scarce, there is a type which the believer in their telepathic explanation will have to accept as supporting the doctrine which I am indicating. Coincidental dreams and apparitions of the living, if they are, explained by telepathy, will have to be regarded as telepathically initiated hallucinations. The number of such phenomena is very great and it would require several volumes simply to quote them. I can only refer the reader to
Phantasms of the Living (2 Vols.) and the Proceedings of the Society for Psychical Research for innumerable instances. They represent definite visual and auditory phantasms in connection with the actual or supposable thoughts of others at a distance, and if explicable by telepathy must be regarded as hallucinations thus instigated. In any case, they represent extra-organic stimuli of a delicate type, and most probably, in many cases most certainly, coincidental with the thoughts of definite persons so indicated in the experience.
7. If thoughts of the living can produce hallucinations at a distance, it is but a step to the supposition that the dead, if they actually survive death, can produce similar effects. Of course we have first to produce evidence that they do survive before we can explain any individual instance of apparition of the deceased by such capacities. But it will be only a matter of the frequency of them, of the conditions under which they occur. and of the supernormal information communicated by them, to prove that personal consciousness does survive, and the evidence for this may carry with it the indications of the phenomena which I am discussing. There are on record a sufficient number of apparitions of the dead to suggest, if they do not prove, that they have an explanation similar to the apparitions of the living; namely, as telepathically induced by the person involved in the apparition. Of course if we do not accept the explanation that coincidental dreams and apparitions of the living are telepathic, we should hardly refer the apparitions of the dead to the same type of cause, though we should probably have to accept an explanation which involved the survival of personality after death, whatever else we had to assume to explain the differences in the whole class. But assume that telepathy is involved in coincidental dreams and apparitions of the living, and the theory that hallucination is the effect by which the identity of the person or event is manifested becomes a foregone conclusion, and the most natural interpretation which would follow for apparitions of the dead would be that they were telepathically initiated hallucinations instigated by the deceased.
The consequence of this is that "spirit clothes" ought not to give the psychologist any perplexity. He manifests no special perplexity at the appearance of clothes in apparitions of the living. There is difficulty in the apparitions of clothes of the living, but neither is it more than the difficulty of telepathic phantasms of any kind, nor is it so great as the common mind must suppose in apparitions of the dead taken for indicating the reality of what appears. The common mind comes to these phenomena with the representative theory of perception, and with this we cannot easily accept the realistic interpretation of apparitions of the dead. We cannot easily believe, if we can at all believe, that the dead, assuming that they exist, duplicate the phenomena of the physical world to such an extent. But after accepting without hesitation the phenomena of clothes and other physical accompaniments in the apparitions of the living, and accepting them as telepathic hallucinations, there ought not to
be any difficulty in explaining apparitions of "spirit clothes" in the same way. To him who does not accept the representative theory of sense-perception the case is clearly possible, and it harmonizes completely with the whole doctrine of hallucination which supposes external causes of the phenomena, but does not conceive those causes as representative in their effects. They are much less apparently so than normal experience, but exhibit a complete antithesis between what seems to be and what is taken to be the real cause.
This view of sense-perception is clearly indicated in telepathic hallucinations. The phantasm cannot be easily assumed to
represent the thought of the agent. The phantasm takes the form of a sensory object, when it is hallucinatory at all in telepathic coincidence, while we never conceive inner states of consciousness or thoughts as having sensory form. The fact that many of the telepathic messages do not take the sensory or hallucinatory form, but are mere thought-impressions or unconscious and automatic reproductions of what is in the mind of the agent, shows unmistakably that the form which the evidence of telepathy takes is not necessary to its character. The distinction between the cause and the effect is then clear, and the same general principles apply to the interpretation of such coincidences as we apply in normal experience. The only question which we have to answer is whether the coincidence between the thoughts of living persons and the apparitions of the living shows that the
phenomena are not due to chance; and once admit causality into their explanation, we have extraorganic agencies of a mental type to reckon with, and there may be no limit to their influence in producing similar coincidences. All that we should require would be extreme caution in estimating the evidence or the claims that such causes actually did operate.
8. The conclusion of this discussion is that we do not require to wholly deny that apparitions of the dead are hallucinations. We have found a point of view in which we can mediate between this explanation of them and the claim that they indicate an objective reality occasioning them. The fact is that the doctrine which explains them as subjective hallucinations, meaning that they do not indicate the objective cause apparent in them, is subject to two difficulties. The first is that it ignores the evidence that the experiences are objectively or extra-organically initiated. In other words, it assumes chance where it would not do so in the subjective experiences. The second is that its contention obtains its force entirely from the assumption of the representative theory of sense-perception. This theory supposes that in normal experience the external object is represented by sensation, that we see it exactly as its nature appears to be. Accepting this view of normal experience, the contrast or antithesis between it and what is found to be the case in hallucinations serves as an evidence of the subjective nature of the latter and conceals the circumstance that hallucinations have causes analogous with the causes of normal sensations. Hence when we give up the representative theory of normal experience, we find that the relation between it and hallucinatory sensations is closer than we at first suppose and that the only thing required to establish an objective or extra-organic stimulus for hallucinations is such a uniform and general coincidence between the hallucination and a cause which we would have to assume in the normal instances that we should be forced to postulate the external reality to account for the fact. That is to say, if we find a certain type of subjective experiences coincidental with extra-organic events to an extent beyond chance, we will have to conclude to the external causality, precisely as we do in all other scientific phenomena. It is a question of the number of coincidences between external and internal events, and when this is supposed to be causal the other matter is determined as it is in all other instances. We may call the subjective effect hallucination if we like, but the fact will not eliminate the principle of causality from it nor the special cause which the facts suggest, though the phenomena do not represent the nature of that cause any more than they do in subjective hallucinations. We simply distinguish the cases as veridical to indicate that they have a given objective cause, such as the facts justify us in supposing.
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