sensed presence

   Also known as sense of presence, feeling ofa presence (FOP), idea of a presence, hallucination of presence, false proximate awareness, false bodily awareness, intruder hallucination, somaesthetic phantom double, somaesthetic doppelgänger, heatoscopy without optical image, phantom impressions, Anwesenheit, concrete awareness, and vivid physical awareness (leibhafte Bewusstheit). All these terms are used to denote the intuitive feeling of someone or something nearby who cannot be perceived, or appears to reside at the fringe of vision. Sensed presence may be accompanied by *visual, *auditory, *olfactory, and/or * tactile hallucinations, but the phenomenon itself is considered to have no perceptual characteristics. The German psychiatrist and philosopher Karl Jaspers (1883-1969) has been credited with first describing the phenomenon at length, designating it as * leibhafte Bewusstheit.AsJaspers explains, "In such cases we are aware that something is present which at that moment is not based on any obvious sensory sign." Jaspers distinguishes three features characteristic of sensed presence, comprising a sense of urgency, a sense of certainty, and a sense of vividness. Although sensed presence tends not to be classified as a * hallucination proper, multiple references to the alleged hallucinatory nature of sensed presence can be found in the literature, sometimes with a reference to the observation made by the American psychologist and philosopher William James (1842-1910) that intuitive feelings such as sensed presence may be conceptualized as "imperfectly developed hallucinations". Jaspers does not follow James in this respect, although he leaves open the possibility of a further development of sensed presence into a *hallucination proper. Others have sought to solve this clas-sificatory issue by designing novel categories of human experience (such as * hallucinoid experience and * minor hallucination) to which sensed presence can be assigned. In still other classifications, sensed presence is relegated to the class of * autoscopic phenomena. The latter solution is perhaps defendable in cases of sensed presence involving an illusory double of one's self. In or shortly before 1917, the German theologist Rudolf Otto (1869-1937) coined the terms * numinous and numen praesens to denote the sensed presence of a sacred or daemonic entity. Sensed presence is a phenomenon known to many healthy individuals. However, a heightened incidence of sensed presence has been described in a variety of pathological conditions. These include hysteria, *psychotic states, *aurae occurring in the context of paroxysmal neurological disorders such as migraine and epilepsy, Parkinson's disease, * hypnagogic and * hypnopompic states, and REM-related parasomnias such as *sleep paralysis. Sensed presence occurring during sleep paralysis has been associated with REM-related endogenous activation of a hypervigilant and biased attentive state. It has been claimed by the American-Canadian neuropsychologist Michael A. Persinger (b. 1945) that sensed presence can be evoked experimentally with the aid of a *Koren helmet or God helmet, as this device is colloquially referred to.

   References

   Brugger, P., Regard, M., Landis, Th. (1997). Illusory reduplication of one's own body: Phenomenology and classification of auto-scopic phenomena. Cognitive Neuropsychiatry, 2, 19-38.

   Cheyne, J.A. (2001). The ominous numinous. Sensed presence and 'other' hallucinations. Journal ofConsciousness Studies, 8, 133-150.

   Fénelon, G., Mahieux, F., Huon, R., Ziégler, M. (2000). Hallucinations in Parkinson's disease: Prevalence, phenomenology and risk factors. Brain, 123, 733-745.

   Jaspers, K. (1997). General psychopathology. Volume 1. Translated by Hoenig, J., Hamilton, M.W. Baltimore, MA: Johns Hopkins University Press.

   Reed, G. (1972). The psychology ofanomalous experience. A cognitive approach. London: Hutchinson & Co.