Akademik

(RVS)

   A term introduced in or shortly before 1960 by the American military research psychologists Thomas I. Myers and Donald B. Murphy in an attempt to operationalize what is actually measured in studies of "visual hallucinations and visual " imagery. As noted by the authors, the subjective and private nature of these phenomena prevents researchers from accessing them directly, i.e. other than through self-observation. As a consequence, research into hallucinatory phenomena in third parties is always dependent on reports of hallucinations. This holds true even for present-day functional imaging studies, which are capable of corroborating hallucinatory activity within the CNS, but not without the subject's aid in indicating the qualitative and temporal aspects of their hallucinations. Strictly speaking, therefore, the raw material of empirical hallucinations research consists of linguistic utterances. This point of view is echoed in the definition of hallucinations as advocated by the British historian of psychiatry German E. Berrios, which runs as follows: "Hallucination is the generic name for a class of utterances reporting subjective experiences (puta-tively) perceptual in nature which occur in the (arguable) absence of an adequate external stimulus." Although this line of reasoning brings a certain sobering and refreshing element to the scientific study of hallucinations, its employment for empirical research purposes has been criticized on various grounds. As the American psychologist A. Michael Rossi maintains in reference to Myers and Murphy's operational definition of the RVS, "The operational definition of the term explicitly limits its reference solely to reports. Proper use of the phrase requires that differences between various imagery experiences be ignored, and, indeed, that experience itself be ignored. Because interest of much sensory deprivation research has been on imagery experiences (as reflected in reports, but not equated with reports), the operationally defined term is inadequate in discussing these results or the interpretation of them... The use of an operationally defined term such as 'reported visual sensation' is valuable when it is used consistently and appropriately.

   It can only lead to additional confusion, however, when it is used inconsistently to refer to the report, the experience, or both." In analogy to the expression 'reported visual sensation', the term " reported auditory sensation (RAS) has been proposed to refer to (reports of) auditory hallucinations and imagery. The general suspicion that individuals reporting a hallucination may not necessarily be referring to a perceptual phenomenon has led to the introduction of the notion "sensory delusion.

   References

   Berrios, G.E. (2005). On the fantastic apparitions of vision by Johannes Müller. History of Psychiatry, 16, 229-246.

   Myers, T.I., Murphy, D.B. (1960). Reported visual sensation during briefexposure to reduced sensory input. Research memo from the Human Resources Research Office, George Washington University. Alexandria, VA.

   Rossi, A.M. (1969). General methodological con-siderations.In: Sensory deprivation: Fifteen years of research. Edited by Zubek, J.P. New York, NY: Appleton-Century-Crofts.