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   Also known as poltergeist effect and poltergeist activity. All three terms are indebted to the German noun Poltergeist, which means rattling ghost or rumbling ghost. In parapsychology they are used to denote a variety of sounds and movements of objects which lack a physical explanation, and which are therefore attributed to the interventions of a poltergeist. At least since the Middle Ages, poltergeists have been conceptualized as invisible spirits who have the capacity to produce sounds (such as raps and crashing noises), to move or break objects, to set fire, and to levitate objects and occasionally even persons. In parapsychology, their presence is typically assumed when such unexplained disturbances occur repeatedly in the vicinity of a child or adolescent, less often in the vicinity of an adult. Because of the apparent association with a person rather than a place, an alternative parapsychological explanation is that poltergeist manifestations are due to subconscious telekinetic or psychokinetic abilities of the individual involved, rather than to the action of spirits. The historical literature abounds with references to poltergeist manifestations. There are several well-documented cases from authorities such as the British physicist William Fletcher Barrett (1844-1925), the French physiologist and Nobel laureate Charles Robert Richet (18501935), the Italian psychiatrist and criminologist Cesare Lombroso (1836-1909), and the Swiss psychiatrists Eugen Bleuler (1857-1939) and Carl Gustav Jung (1875-1961). In biomedicine, alleged poltergeist manifestations tend to be attributed to fraud, self-delusion, or hallucinatory or illusory experiences. The perceived noises may also be designated as * nonverbal auditory hallucinations (i.e. *akoasms), which may take the form of a * collective hallucination when they are perceived simultaneously by various individuals. It has also been suggested that alleged poltergeist manifestations which are not attributable to fraud may be due to physical forces, such as electromag-netism, static electricity, ultrasound, or a Casimir effect.

   References

   Bleuler, E. (1930). Vom Okkultismus und seine Kritiken. Zeitschrift für Parapsychologie, 11, 654-680.

   Jung, C.G. (1961). Memories, dreams, reflections. Translated by Winston, R., Winston, C. Recorded and edited by Jaffé, A. London: Routledge & Kegan Paul.

   Roll, W.G. (1972). The poltergeist. Metuchen, NJ: Nelson Doubleday.