In the meantime I pass on to that group of the dynamogenic effects of suggestion which affect the more central vital operations—either the vaso-motor system, or the neuro-muscular system, or the central sensory tracts. The effects of suggestion on character—induced changes to which we can hardly guess the nervous concomitant—will remain to be dealt with later.
First, then, as to the effects of suggestion on the vaso-motor system. Simple effects of this type form the commonest of "platform experiments." The mesmerist holds ammonia under his subject's nose, and tells him it is rose-water. The subject smells it eagerly, and his eyes do not water. The suggestion, that is to say, that the stinging vapour is inert has inhibited the vaso-motor reflexes which would ordinarily follow, and which no ordinary effort of will could restrain. Vice versâ, when the subject smells rose-water, described as ammonia, he sneezes and his eyes water. These results, which his own will could not produce, follow on the mesmerist's word. No one who sees these simple tests applied can doubt the genuineness of the influence at work. We find then, as might be expected, that action on glands and secretions constitutes a large element in hypnotic therapeutics. The literature of suggestion is full of instances where a suppressed secretion has been restored at a previously arranged moment, almost with "astronomical punctuality." And yet to what memory is that command retained? by what signal is it announced? or by what agency obeyed?
In spite of this underlying obscurity, common to every branch of suggestion, these vaso-motor phenomena are by this time so familiar that no further description of them is necessary.
This delicate responsiveness of the vaso-motor system has given rise to some curious spontaneous phenomena, and has suggested some experiments, which are probably as yet in their infancy. The main point of interest is that at this point spontaneous self-suggestion, and subsequently suggestion from without, have made a kind of first attempt at the modification of the human organism in what may be called fancy directions,—at the production of a change which has no therapeutic aim, and so to say, no physiological unity; but which is guided by an intellectual caprice along lines with which the organism is not previously familiar. I speak of the phenomenon commonly known as "stigmatisation," from the fact that its earliest spontaneous manifestations were suggested by imaginations brooding on the stigmata of Christ's passion;—the marks of wounds in hands and feet and side. This phenomenon, which was long treated both by savants and by devotees as though it must be either fraudulent or miraculous,—ou supercherie, ou miracle,—is now found (like a good many other phenomena previously deemed subject to that dilemma) to enter readily within the widening circuit of natural law. Stigmatisation is, in fact, a form of vesication; and suggested vesication—with the quasi-burns and real blisters which obediently appear in any place and pattern that is ordered—is a high development of that same vaso-motor plasticity of which the ammonia-rose-water experiment was an early example.[81]
The group of suggestive effects which we reach next in order is a wide and important one. The education of the central sensory faculties,—of our power of inwardly representing to ourselves sights and sounds, etc.,—is not less important than the education of the external senses. The powers of construction and combination which our central organs possess differ more widely in degree in different healthy individuals than the degrees of external perception itself. And the stimulating influence of hypnotism on imagination is perhaps the most conspicuous phenomenon which the whole subject offers; yet it has been little dwelt upon, save from one quite superficial point of view.
Every one knows that a hypnotised subject is easily hallucinated;—that if he is told to see a non-existent dog, he sees a dog,—that if he is told not to see Mr. A., he sees everything in the room, Mr. A. excepted. Common and conspicuous, I say, as this experiment is, even the scientific observer has too often dealt with it with the shallowness of the platform lecturer. The lecturer represents this induced hallucinability simply as an odd illustration of his own power over the subject. "I tell him to forget his name, and he forgets his name; I tell him that he has a baby on his lap, and he sees and feels and dandles it." At the best, such a hallucination is quoted as an instance of "mono-ideism." But the real kernel of the phenomenon is not the inhibition but the dynamogeny;—not the abstraction of attention or imagination from other topics, but the increased power which imagination gains under suggestion;—the development of faculty, useless, if you will, in that special form of imagining the baby, but faculty mentally of a high order—faculty in one shape or another essential to the production of almost all the most admired forms of human achievement.
On this theme I shall have much to say; yet here again it will be convenient to defer fuller discussion until I review what I have termed "sensory automatism" in a more general way. We shall then see that this quickened imaginative faculty is not educed by hypnosis alone; that it is a part of the equipment of the subliminal self, and will be better treated at length in connection with other spontaneous manifestations. Enough here to have pointed out the main fact; for when pointed out it can hardly be disputed, although its significance for the true comprehension of hypnotic phenomena has been too often overlooked.
Yet here, and in direct connection with hypnotism, certain special features of hallucinations need to be insisted upon, both as partly explaining certain more advanced hypnotic phenomena, and also as suggesting lines of important experiment. The first point is this.
Post-hypnotic hallucinations can be postponed at will. That is to say, a constant watchfulness is exercised by the subject, so that if, for example, the hypnotiser tells him that he will (when awakened) poke the fire when the hypnotiser has coughed three times, the awakened subject, although knowing nothing of the order in his waking state, will be on the look-out for the coughs, amid all other disturbances, and will poke the fire at the fore-ordained signal.[82] Moreover, when the post-hypnotic suggestion is executed there will often be a slight momentary relapse into the hypnotic state, and the subject will not afterwards be aware that he has (for instance) poked the fire at all. This means that the suggested act belongs properly to the hypnotic, not to the normal chain of memory; so that its performance involves a brief reappearance of the subliminal self which received the order.
Another characteristic of these suggested hallucinations tells in exactly the same direction. It is possible to suggest no mere isolated picture,—a black cat on the table, or the like,—but a whole complex series of responses to circumstances not at the time predictable. This point is well illustrated by what are called "negative hallucinations" or "systematised anæsthesiæ." Suppose, for instance, that I tell a hypnotised subject that when he awakes there will be no one in the room with him but myself. He awakes and remembers nothing of this order, but sees me alone in the room. Other persons present endeavour to attract his attention in various ways. Sometimes he will be quite unconscious of their noises and movements; sometimes he will perceive them, but will explain them away, as due to other causes, in the same irrational manner as one might do in a dream. Or he may perceive them, be unable to explain them, and feel considerable terror until the "negative hallucination" is dissolved by a fresh word of command. It is plain, in fact, throughout, that some element in him is at work all the time in obedience to the suggestion given,—is keeping him by ever fresh modifications of his illusion from discovering its unreality. Nothing could be more characteristic of what I have called a "middle-level centre" of the subliminal self—of some element in his nature which is potent and persistent without being completely intelligent;—a kind of dream-producer, ready at any moment to vary and defend the dream.