Akademik

   The term coincidental hallucination is indebted to the Latin noun coincidentia, which means simultaneous occurrence. It used to denote a type of hallucination that is believed to coincide in a meaningful way with an actual event taking place in the external world. In reports ofhallucinations designated as coincidental the images tend to be visual or compound in nature, although auditory and tactile phenomena are reported as well. These images can depict any given situation or event, but in the literature they often pertain to an individual who is ill or dying at the moment the hallucination takes place. When a temporal as well as an intrinsic relation can be demonstrated between the actual individual and the hallucination at hand, the term * veridical hallucination is used. Both coincidental and veridical hallucinations are sometimes conceptualized as *telepathic hallucinations, although other putative mechanisms have also been suggested by parapsycholo-gists. Claims of having experienced a coincidental hallucination have been made from the earliest times to the present day. The multitude of claimed contacts with the dead circulating during the latter half of the 19th century culminated in the publication of the book Phantasms ofthe Living by the British paranormal investigators Edmund Gurney (1847-1888), Frederic Myers (1843-1901), and Frank Podmore (1856-1910). This book contains 5,700 first-hand descriptions of * apparitions. It proved a major source of inspiration for the * Census of Hallucinations, carried out between 1889 and 1892 by the Society for Psychical Research (SPR) among 17,000 individuals in the non-institutionalized population of the United Kingdom. Within this population the SPR found a sky-rocketing odds ratio of 440 for the occurrence of coincidental hallucinations. As a corollary, the SPR concluded that "between deaths and apparitions of the dying person a connexion exists which is not due to chance alone." However, critics such as the German hallucinations researcher Edmund Parish (1861-1916) suggest that a substantial number of the reported * visions are really * memory hallucinations (i.e. false memories conjured up afterwards to fit a meaningful mould) or other types of *non-coincidental hallucinations. In the final analysis, it would seem that the issue of whether or not to believe in the possibility of coincidental and veridical hallucinations is not decided by empirical studies, even when they are carried out as thoroughly as the SPR's.

   References

   Gurney, E., Myers, F.W.H., Podmore, F. (1886). Phantasms of the living. Volumes 1 and 2. London: Trübner.

   Parish, E. (1897). Hallucinations and illusions. A study ofthe fallacies ofperception. London: Walter Scott. Sidgwick, H., Johnson, A., Myers, F.W.H., Pod-more, F., Sidgwick, E. (1894). Report on the census ofhallucinations.In: Proceedings ofthe Society for Psychical Research. Volume XXVI. Part X. London: Kegan Paul, Trench, Trübner &Co.