Also referred to as dual consciousness, duplication of consciousness, doubling of awareness, double perceptions, and secondary personality. During the late 19th century these terms, and probably many more, were used to denote a condition in which two distinct mental states coexist within a single individual. It is not clear who introduced the notion of double consciousness, but a German physician named Jensen is credited with being among the first to draw clinical attention to it. In 1868 Jensen used the German term Doppelwahrnehmung to denote what today is known as the déjà vu phenomenon. In the field of hallucinations research the term double consciousness is used to denote a mental state in which two streams of perceptual information - consisting, say, of * scenic hallucinations on the one hand, and regular sense perceptions on the other - are experienced simultaneously. The Canadian neurosurgeon Wilder Graves Penfield (1891-1976) used the term to denote the mental state described by individuals experiencing * reperceptive hallucinations due to cortical probing. As Penfield wrote, "Consider the point of view of the patient when the surgeon's electrode, placed on the interpretive cortex, summons the replay of past experience. The stream of consciousness is suddenly doubled for him. He is aware of what is going on in the operating room as well as the 'flashback' from the past. He can discuss with the surgeon the meaning of both streams." An analogous phenomenon was described by the Cypriot philosopher and psychologist Andreas Mavromatis in the context of his work on *hypnagogic hallucinations. As Mavromatis points out, trained - and sometimes untrained - individuals can have "hypnagogic experiences in a state of double-consciousness in which [they] although deeply involved in their imaginal activities are still aware of their physical surroundings." A third example of double consciousness is the mental state accompanying the * lucid dream, characterized by the experience of the dream itself as well as the acute awareness that one is dreaming. When instances of * out-of-body experience (OBE) and *heautoscopy are experienced in rapid alternation, they are also referred to as double consciousness.
References
Brugger, P., Regard, M., Landis, Th. (1997). Illusory reduplication of one's own body: Phenomenology and classification of autoscopic phenomena. Cognitive Neuropsychiatry,2, 19-38.
Jensen (1868). Ueber Doppelwahrnehmungen in der gesunden, wie in der kranken Psyche. Allgemeine Zeitschrift für Psychiatrie, 25(Supplement-Heft), 48-63.
Mavromatis, A. (1987). Hypnagogia. The unique state ofconsciousness between wakefulness and sleep. London: Routledge.
Penfield, W. (1975). The mystery of the mind. A critical studyofconsciousness and the human brain. Princeton, NJ: Princeton University Press.
Dictionary of Hallucinations. J.D. Blom. 2010.