CHAPTER XXI

HALLUCINATIONS AND PSEUDO-HALLUCINATIONS

WE must emphasize the fact that persons who happen to have occasional hallucinations may not be subjects of secondary sensations. They may happen to have been under conditions which produced in them a sensory disaggregation and the formation of new and temporary sensory association, giving rise to hallucinations. But this condition of the nervous system vanishes with the disappearance of the conditions themselves. Such states are produced by toxic agents, such as hashish, opium, morphine, and other hypnotics. As soon as the operating causes are removed the nervous system returns to its previous condition.

    In the case of sane individuals who happen to have illusions or hallucinations there are two criteria used for a verification of the correspondence of internal percepts formed in response to external objects. One is (a) sensory, and the other (b) social.

         If a man perceives an object and wishes to satisfy himself that it is really there, he verifies it by means of other sense organs. Thus if one sees an apple or hears a sound and wishes to determine whether the object is really there, he goes to the object, examines it with his other senses. If he hears a bell or organ, he goes and verifies its presence by the sense of sight and touch.

           This, however, is not the only criterion, for man in psychopathic states or under the influence of certain toxic or autotoxic agents may have hallucinations of any or all of his sense organs. In fact, hallucinations of all the organs sometimes occur. Man, therefore, has often recourse to the other criterion, the social one. He seeks verification of the existence of an external object from his fellow beings. When one hears a voice or a sound, he turns to his companion to learn if he too heard it, and if others present do not confirm his perception of sound or sight, the sane man will consider it as an hallucination.

         It is shown by statistics that at least one in ten normal individuals has had an hallucination once in his life. However, as in the case of illusions, hallucinations are much more often found in insanity when there is present a more permanent and more extensive disturbance of psycho-physiological processes. The hallucinations, therefore, are not only more frequent, but more persistent than in sane persons.

        While sane persons have more often visual hallucinations, in the insane auditory hallucinations predominate. This does not mean that sane persons may not have auditory hallucinations, but the latter are not so persistent. In fact, I have good reasons for believing that many young children have auditory hallucinations and illusions.

       It may be that those with auditory hallucinations more often form delusions than those having the visual, since speech is more impressive. Speech is the medium of social intercourse, which lies at the base of growth and intelligence in man, and hence the social criterion is an important factor in the formation, by persistent suggestion, of our belief in the existence of an external object. The patient therefore who persistently hears external voices lives in a social environment of his own that gives him the suggestion and assurance of the real existence of the hallucination, and thus a delusion is developed. In short, it is quite conceivable that one should form a delusion by experiencing persistent auditory hallucinations.

           Even in normal persons hallucinations and illusions are not uncommon when sleep comes or goes. These are known as hypnagogic or hypnapagogic hallucinations. They always appear in the intermediary state between the waking and sleeping states. At this time also occur the “nightmares” which really consist of hypnagogic hallucinations and illusions.

        Hallucinations may occur while the person is passing from the waking to the sleeping state or vice versa. Such hallucinations and illusions, hypnagogic and hypnapagogic, are due to the fact that when man wakens or goes to sleep any of the senses may be awakened, and these senses give rise to percepts or to secondary sensations with their accompanying percepts. Very vivid dreams are of the same nature.

      Pseudo-hallucinations are forms of hallucinations in which the sensory element is not strong and the subject is not sure of its existence; he does not project it into the external world, and still in some vague manner he refers it to some agency in the external world. Those persons who hear internal voices have pseudo-hallucinations. This condition is probably the beginning of the more pronounced form of hallucination into which the pseudo-form may sooner or later develop. The manifestation of pseudo-hallucinations is the beginning of the process of disaggregation and of the formation of new sensory associations.

        Pseudo-hallucinations may be temporary, occurring only once, or they may become persistent. It must not however be understood that pseudo-hallucinations must necessarily precede fixed hallucinations. It depends simply upon the process of disaggregation and the formation of new sensory associations. The process may be a slow one, beginning with pseudo-hallucinations, or may be intense, having at once full fledged hallucinations. This in its turn is dependent on the intensity of the stimulus causing the condition, and on the predisposition of the patient to such a disaggregation and formation of new sensory associations.