1. The normal state of consciousness upon which the discussion of the foregoing paragraphs has been based may undergo such a variety of changes that general psychology must give up the attempt to discuss these changes in detail. Then, too, the more important of these changes, namely those which are observed in the various forms of nervous diseases, brain-diseases, and insanity, belong to special branches of pathology which border upon psychology and are more or less dependent upon it. All that psychology can do is to indicate the main psychical conditions of abnormal states. We may distinguish in general three kinds of such conditions. They may consist 1) in the abnormal character of the psychical elements, 2) in abnormalities in the way in which psychical compounds are constituted, and 3) in abnormalities in the way in which psychical compounds are combined. As a result of the intimate interconnection of these different kinds of conditions it hardly ever happens that one of these three conditions is operative alone; all three usually unite. The abnormal character of the elements results in abnormalities of the compounds, and this in turn brings about changes in the general interconnection of conscious processes.

2. The psychical elements, that is sensations and simple feelings, show only such changes as result from some disturbance in the normal relation between them and their psycho-physical conditions. In the case of sensations such changes may be reduced to an increase or decrease of the sensitivity for stimuli (hyperaesthesia and anaesthesia) resulting especially from the action of certain physiological influences within the sensory centers. The most important psychological symptom in this case is the increased excitability which is one of the most common factors of complex psychical disturbances. In similar fashion, changes in the simple feelings betray themselves in states of depression or exaltation as a decrease or increase in the affective excitability. These different states may be recognized from the way in which the emotions and volitional processes occur. Thus, changes in the psychical elements can be demonstrated only by the influence that they exercise on the character of the various psychical compounds.

3. The defects in ideational compounds arising from peripheral or central anaesthesia are generally of limited importance. They have no far-reaching effect on the interconnection of psychical processes. It is essentially different with the relative increase in the sensation which results from central hyperaesthesia. The effect of such hyperaesthesia is especially important because when it is present, reproduced sensation elements may become as intense as external sense impressions. The result may be that a pure memory image is objectified as a sense perception. This is an hallucination. Or, when elements are united which are partly from direct external stimulation, partly from reproduction, the sense impression may be essentially modified through the intensity of the reproduced elements. The result is then an illusion of fancy ¹⁾. The two abnormalities are not always distinguishable, for though in many cases particular ideas can be shown to be illusions of fancy, the presence of pure hallucinations is almost always doubtful because it is so easy to overlook some direct sensation elements. In fact, it is by no means improbable that the great majority of so-called hallucinations are illusions. These illusions are in their psychological character nothing but assimilations (p. 257 sq.). They may be defined as assimilations in which the reproduced elements predominate. Just as normal assimilations are connected with successive associations, so for the same reason, the illusions of fancy are closely related to the changes in the associative ideational processes to be discussed later (5).
 
 

1) The expression "illusions of fancy" is used when this class of illusions is to be distinguished from the sense illusions which appear in the normal state of consciousness, as for example from the radiating form of the stars, which is due to the refraction of light in the crystalline lens, or the varying apparent size of the sun or moon at the horizon and at the zenith.
 
 
 
 

4. In the case of complex affective and volitional processes the abnormal states are clearly distinguishable as states of depression and exaltation. The state of depression is due to the predominance of inhibitory, asthenic emotions, that of exaltation to a predominance of exciting, sthenic emotions, while at the same time we observe, in the first case a retardation or complete checking of resolution, in the second an exceedingly rapid, impulsive activity of the motive. In this sphere it is generally more difficult to draw the line between normal and abnormal conditions than in the sphere of ideational compounds, because even in normal mental life the affective states are continually changing. In pathological cases the change between states of depression and exaltation, which are often very striking, appear merely as intensification of the normal oscillation of the feelings and emotions about an indifference-condition (p. 92). States of depression and exaltation are especially characteristic symptoms of general psychical disturbances; their detailed discussion must therefore be left to psychical pathology. General psychical disturbances are always symptoms of diseases of the brain, so that these abnormalities in affective and volitional processes are doubtless accompanied, like abnormalities of the sensations and ideas, by physiological changes. The nature of these changes is, however, still unknown. We can only surmise, in accordance with the more complex character of affective processes, either that they are more extensive than the changes in central excitability accompanying hallucinations and illusions, or that they affect the central cortial regions directly concerned in apperceptive processes.

5. Connected with these changes in the sensory excitability and with states of depression and exaltation, there are, as a rule, simultaneous changes in the interconnection and course of psychical processes. Using the concept consciousness which we employ to express this interconnection (p. 228), we may call these changes abnormal changes of consciousness. So long as the abnormality is limited to the single psychical compounds, ideas, emotions, and volitions, consciousness is of course changed because of the changes in its components, but we do not speak of an abnormality of consciousness itself until the abnormality appears, not merely in the single compounds, but also in the combinations of these compounds. Such changes in the combinations always arise when the elementary disturbances become greater, because the combinations of elements into compounds and of compounds with one another, are processes which pass continuously into each other. Corresponding to the different kinds of combination which make up the interconnection of consciousness (p. 251), there may be distinguished in general three kinds of abnormalities of consciousness: 1) changes in the associations, 2) changes in the apperceptive combinations, and 3) changes in the relation of the two forms of combination.

6. Changes in associations are the first to result directly from the elementary disturbances. The increase of sensory excitability changes normal assimilations into illusions of fancy, and this results in an essential disturbance in the associative processes of recognition (p. 264). Sometimes that which is known to the subject appears to be unknown, and then again what is unknown appears familiar, according as the reproduced elements are connected with definite earlier ideas, or are derived from perceptions which have only a remote relation to one another. Then, too, the increased sensory excitability tends to accelerate the association, so that the most superficial connections, which are occasioned by accidental impressions or by habit, are the ones that predominate. The states of depression and exaltation, on the other hand, determine mainly the quality and direction of the association.

In a similar manner the elementary ideational and affective changes influence apperceptive combinations, either retarding or accelerating them, or else determining their direction. Still, in these cases all marked abnormalities in ideational or affective processes result in an increase, to a greater or less degree, of the difficulty of carrying out the processes connected with active attention, so that often, only the simpler apperceptive combinations are possible, sometimes only those are possible which through practice have become simple associations. Connected with the last mentioned fact are the changes which take place in the relation between apperceptive and associative combinations. The influences discussed thus far are in the main favorable to associations, but unfavorable to apperceptive combinations. In keeping with this is the fact that one of the most frequent symptoms of a far-reaching psychical abnormality is a great preponderance of associations. This is most obvious when the disturbance of consciousness is a continually increasing process, as it is in many cases of insanity. The observation may be made in such cases that the functions of apperception, that is, the so-called processes of imagination and understanding are more and more supplanted by associations, until finally the latter are all that remain. If the disturbance progresses still further, the associations gradually become more limited and confined to certain habitual combinations (fixed ideas). Finally this state gives place to one of complete mental paralysis.

7. Apart from mental diseases in the strict sense of the term, the irregularities of consciousness just discussed are to be found in two conditions which appear in the course of normal life, in dreams and hypnosis.

The ideas which arise in dreams come, at least to a great extent, from sensations, especially from those of the general sense, and are therefore mostly illusions of fancy, probably only seldom pure memory ideas which have become hallucinations. The decrease of apperceptive combinations in comparison with associations, is also striking and goes to explain the frequent modifications and exchanges of self-consciousness, the confusion of the judgment, etc. The characteristics of dreams which distinguish them from other similar psychical states, are to be found, not so much in these positive attributes, as in certain negative attributes. The increase of excitability is limited entirely to the sensory functions, the external volitional activity being completely inhibited in ordinary sleep and dreams. When the fanciful ideas of dreams are connected with corresponding volitional acts, we have the very infrequent phenomena of sleep-walking, which are related to certain forms of hypnosis. Motor concomitants are generally limited to articulations, and appear as talking in dreams.

8. Hypnosis is the name applied to certain states related to sleep and dreams and produced by means of certain definite psychical agencies. Consciousness is here generally in a condition halfway between waking and sleeping. The main cause of hypnosis is suggestion, that is, the communication of an idea strong in affective tone. This communication generally takes the form of a command from some other person (outward suggestion), but may sometimes be given by the subject himself, when it is called autosuggestion. The command or resolution to sleep, to make certain movements, to perceive certain objects which are not present, or not to perceive objects which are present, etc., — these are the most frequent suggestions. Monotonous stimuli, especially tactual stimuli are helpful auxiliaries. Then, too, there is a certain disposition of the nervous system of unknown character, which is necessary for the rise of the hypnotic state and this disposition is decidedly increased when the state is repeatedly produced.

The first symptom of hypnosis is the more or less complete inhibition of external volitional acts. This is connected with a concentration of the attention on one thing, generally the command of the hypnotizer (automatism). The subject not only sleeps at command, but retains in this state any position which is given him, however unnatural (hypnotic catalepsy). If the sleep becomes still deeper the subject makes, to all appearances automatically, the movements which he is directed to make, and he shows that ideas suggested to him appear like real objects (somnambulism). In this last state it is possible to give either motor or sensory suggestions which are to go into effect when the subject awakes, or even at some later time (terminal suggestions). The phenomena that accompany such "posthypnotic effects" render it probable that the after-effects are due either to a partial persistence of the hypnosis or (in the case of terminal suggestions) to a renewal of the hypnotic state.

9. It appears from all these phenomena that sleep and hypnosis are related states, differing only in the fact that their mode of origin is different. They have as common characteristics the inhibition of processes of volition and attention, and a disposition toward aroused excitability in the sensory centers which brings about an assimilation of the sense impressions and thus results in illusions of fancy. The characteristics which distinguish sleep and hypnosis are to be found in the fact that in sleep we observe the complete inhibition of volition, especially the inhibition of the apperceptive function and of every phase of motor function, while in hypnosis we find the concentration of the passive attention on one thing. This concentration is conditioned by suggestion and is at the same time favorable to the reception of further suggestions. These differences are, however, not absolute, for in sleep-walking the will is not completely inhibited, while, on the other hand, it is inhibited in the first lethargic stages of hypnosis just as in ordinary sleep.

Sleep, dreams, and hypnosis are, accordingly, in all probability, essentially the same in their psycho-physical conditions. These conditions consist in the specially modified dispositions to sensation and volitional reactions, and can, therefore, like all such dispositions, be explained on their physiological side only by assuming changes in the activity of certain central regions. These changes have not yet been investigated directly. Still, we may assume from the psychological symptoms that the physiological conditions consist, as a rule, in the inhibition of activity in the regions connected with processes of volition and apperception, and in increased excitability of the sensory centers.

9a. It is then, strictly speaking, a physiological problem to formulate a theory of sleep, dreams, and hypnosis. Apart from the general assumption based on psychological symptoms, of an inhibition of activity in certain parts of the cerebral cortex, and increase in the activity of other parts, we can apply only one general neurological principle with any degree of probability. This is the principle of compensation of functions, according to which the inhibition of the activity of one region is always connected with an increase in the activity of the other interrelated areas. This interrelation may be either direct, neurodynamic, or indirect, vasomotoric. The first is probably due to the fact that energy which accumulates in one region as the result of inhibition, is discharged through the connecting fibers into other central regions. The second is due to contraction of the capillaries as a result of inhibition and a compensating dilation of the blood-vessels in other regions. The increased blood supply due to this dilation is in turn attended by an increase in the activity of the region in question. Judging from the psychological symptoms, one of the essential differences between dreams and hypnosis seems to consist in the fact that in dreams the central regions which are related to apperception are in a more or less completely inactive state, so that all stimulations flow, according to the principle of compensation, to the sensory centers. In hypnosis, on the other hand, it is possible for different regions within the apperception center itself to be so related that while certain of these regions are partially inhibited, others are correspondingly more open to excitation. This line of inference seems to be justified by the examination of certain states of partial hypnosis which may arise through an increased disposition on the part of a subject to become hypnotized, which increased disposition results from practice. In such states of partial hypnosis the subject may carry out in an automatic way complicated acts, all his other functions seeming to be in a waking state. Or he may show certain psychological activities of clearer discrimination, or strikingly exact recognition, or reproduction of certain particular sensations and feelings to the exclusion of all other forms of activity. This last mentioned state of partial hypnosis in which attention is concentrated in a single direction is the only form of hypnosis which can possibly be thought of as having any direct psychological value. This state may be of some value because of the introspection which it renders possible in response to experimentally prepared sensory stimulations. But even in this state the greatest possible care will be necessary to avoid one danger which will always be present, namely the danger that deceptive suggestions from others or from one's self are interfering with the introspection.

Dreams and hypnosis are often made the subjects of mystical and fanciful hypotheses, in some cases even by psychologists. We hear of increased mental activity in dreams and of influence of mind on minds at a distance in dreams and hypnosis. Especially hypnotism has been used in this way, to support superstitious spiritualistic ideas. In connection with "animal magnetism", which may be completely explained by the theory of hypnosis and suggestion, and in connection with "somnambulism", there are a great many cases of self-deception and intentional humbug. In reality all that can stand the light of thorough examination in these phenomena is in general readily explicable on psychological and physiological grounds; what is not explicable in this way has always proved on closer examination to be superstitious self-deception or intentional fraud.

References. On Psychical Disturbances in general: Kraepelin, Psychiatrie, 7th ed., vol. I, 1903. Störring, Vorlesungen über Psychopathologie, 1900. Weygandt, Atlas und Grundriss der Psychiatrie, (1902) Chap. IV. P. Janet, Névroses et idées fixes, vols. 1 and 2, 1898. Sommer, Lehrb. der psychopathol. Untersuchungsmethoden, 1899. Wundt, Grundz., 5th ed., vol. III, chap. 20; Lectures, lectures 21 and 22. On Sleep and Dreams: Purkinje, Wachen, Schlaf und Traum, Handwörterb. d. Physiol., vol. III, Pt. 2. Radestock, Schlaf und Traum, 1879. Giessler Aus den Tiefen des Traumlebens, 1890. Weygandt, Entstehung der Träume, 1893 and Phil. Stud., vol. 20. Michelsen, Tiefe des Schlafes, Kraepelin's Psychol. Arbeiten, vol. 2. On Hypnosis: Bernheim, Die Suggestion, 1888. Forel, Der Hypnotismus, 2nd ed., 1891. Lehmann, Die Hypnose, 1890, 0. Vogt, Zeitschr. f. Hypnotismus, vols. 3—6. Wundt, Phil. Stud., vol. 8. Lipps, Sitzungsber. der Münchener Akad., 1897. vol. 2, and Zeitschr. f. Hypnot., vol. 6.