DOUBLE CONSCIOUSNESS. Double or divided consciousness has likewise been desig nated double personality. The term comprehends a group of morbid mental conditions involving some modification in the clearness of the idea of personal identity. Individu als are often encountered with confused notions of the " me" and " not me;" others• conceive that parts or properties of their frame belong to another person, or that they are inhabited and ruled by a spirit or entity acting in opposition to their will and inter ests; and there are others who, at different times and under different circumstances,. such as when influenced by, or free from moral or physical stimulation, conceive that they arc different persons, and endowed with different qualities and powers. These manifestations, however, do not fully illustrate the state under consideration, which has been described as exhibiting, in some measure, two separate and independent trains of thought, and two independent mental capabilities in the same individual, each train of thought and each capability being wholly dissevered from the other, and the two states in which they respectively predominate, subject to frequent interchanges and alterations. In the most marked or perfect form of this phenomenon, the individual is conscious of the two independent trains of thought, and conceives, in consequence of the apparent independence of these, that he is two distinct persons at the same time. There are few instances of this mental affection on record (see Wigan On Duality of Mind, Abercrom bie's Inquiry into Intellectual Powers, Ellicot in Combe's System of Phrenology, 3d edition). A servant-girl, at the period of puberty, gave evidence of double personality for three months. In an advanced stage of the affection, the circumstances which occurred dur ing the paroxysm were completely forgotten by her when it was over, but were per fectly remembered during subsequent paroxysms. She was, for example, taken to church while in her abnormal state. She shed tears during the sermon, particularly during an account given of the execution of three young men, who had described, in their dying declarations, the dangerous steps with which their career of vice and infamy commenced. When she returned home, she recovered in a quarter of an hour, was quite amazed at the questions put to her about the sermon, and denied that she had been in church; but next night, when taken ill, she mentioned that she had been there, repeated the words of the text, and gave an accurate account of the tragical narrative of the three criminals by which her feelings had been so powerfully affected (Philosoph ical Transactions,, Edin. 1822). This description assimilates the patient to the class of
somnambulists. But such perversions of the faculties generally involve a more palpa ble and complete duality of mind. The personal identity seems to be lost or impaired. A. B. conceived that he was himself and another person at the same time; he acted as if this belief were sincere, and could not divest himself of the conviction that in his body were two minds or persons suggesting courses of conduct widely opposed. He was certain that his original self, A. B., was a base, abandoned scoundrel, tempting his other, or new, or better self—to whom, it should be noted, was attached the emphatic Ego—to commit crimes or acts of which he altogether disapproved. The second person in this duality repelled, struggled with these abominable solicitation, such as that he should commit suicide; and loathed the tempter or first person. This struggle some times became real and visible, when the hands, acting under the will of No. 2, or the virtuous and opposing principle, beat and bruised the legs, body, or head, which, it may be presumed, were supposed to belong to No. 1, the vicious or tempting impulse. The object of the one was obviously to inflict pain upon the other. The blows were so severe as to leave marks for days; and when these were adverted to, the answer was, as. if from No. 2, " Don't justify him, he deserved it." Such conflicts generally occurred during the night, and the interference of the night-watch was required to part or pacify the combatants.* In this case time manifestations of disease might be attributed to the abstruse but vain philosophical inquiries of the mind during health. ,, While it is quite intelligible that habits of protracted self-analysis, or of that abstrac• tion which loses all idea of distinct personality in the act of thinking, or in the subject occuyping attention, may induce such a condition, a more physical explanation has been sought in the alternate morbid activity of different parts of the brain, in the non consentaneous or independent and alternate activity of the two hemispheres of the brain. which, when acting together, are held to be the organ of the mind in its unity and entireness. Latterly, the views of sir William Hamilton have been brought to bear upon the point: and still more recently, the theory called "unconscious cerebration," which supposes certain impressions to exist unperceived, and to become objects of con sciousness only under certain conditions, has been applied to the same purpose; but, in so far as the impairment of the conviction of personal identity is concerned, the prob lem still awaits solution.