Notes on random target selection: The PRL autoganzfeld target and target set distributions revisited

Author(s): Broughton, R. S., Berger, R. E.

Journal/Book: J Parapsychol. 1998; 62: 402 N Buchanan Blvd, Durham, NC 27701-1728, USA. Inst Parapsychology. 339-348.

Abstract: We distinguish between a random target selection procedure which, in principle, excludes sequential dependencies, and a resulting random target sequence that may contain pecullarities-especially in terms of target frequency distribution, which may correspond to a subject's response biases. Post-hoc corrections that adjust the hit probability are available. A correction is not needed in case of a balanced (closed-deck) situation. The distinction is illustrated for the random target selection procedure and the resulting target sequence in the PRL autoganzfeld studies. A conservative correction results in a slight reduction of the overall significance and a reduction in differences in scoring rates on static and dynamic targets, thus weakening. The firm conclusion drawn in the original paper that dynamic targets are superior to static targets. A peculiar target frequency distribution is found which cannot be explained on the basis of the target selection procedure. Most notably, the targets 77, 78, 79, and 80 are over-represented, which results in a strong over-representation of Set 20 which contains these 4 targets. However, the reported deviations from a well-balanced target frequency distribution cannot explain the excess of hits reported for the PRL autoganzfeld study.

Note: Article Bierman DJ, Univ Amsterdam, Roetersstr 15, NL-1018 WB Amsterdam, NETHERLANDS

Keyword(s): GANZFELD; ARTIFACT

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