Metaanalys av Ganzfeld Parapsykologiska bevis, Metaanalys

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Metaanalyser av Ganzfeld

Alias: "meta-analys" av försök, som gjorts med ganzfeldtekniken och metaanalys av ganzfeld


The ganzfeld is a short-term sensory isolation procedure that is commonly used to enhance mental imagery in frr-response ESP experiments. The idea is to help subjects focus attention inward by depriving them of patterned sensory input. This is accomplished in the visual mode by taping halves of ping-pong balls over their eyes and having them look into a red light. For auditory isolation, subjects listen to pink noise (which sounds auditory like a waterfall without the modulation) through headphones. Most people find the ganzfeld procedure a mild but plesant alterd state of consciousness, in addition to facilitating imagery. Subjects are usually in the ganzfeld for 30-45 minutes, during which time they report all their imagery. Meanwhile, a sender in another room tries to influence this imagery by transmitting the contents of a randomly selected picture. Afterwards, subjects are shown four pictures, one of which is a duplicate of the target, and asked to pick out the target based on their imagery.

Honorton (1985) and Hyman (1985) debated the interpretation of 42 ganzfeld studies that had been published up through 1981. Although they agreed that the composite results of these experiments could not be attributed to chanse, they disagreed about whether the results could be attributed to artifacts. Among other things, Hyman noted that in several experiments the picture handled by the sender was included in the judging packet and could have transmitted sensory cues, like fingerprints, that would allow the subject to score a hit on that bias. He also complained that several studies used suboptimal target rendomization procedures, such as shuffling. To make a very long story short, the debate boiled down primarily to disagreement over how the quality of randomization should be coded for the meta-analysis.

The combatants agreed that a decisive conclusion awaited new ganzfeld experiments with clearly acceptable methodology (Hyman & Honorton, 1986). Honorton took up the challenge by developing a highly automated ganzfeld testing paradigm. Pictures were presented to sender and subject by video tape to prevent handling cues, and a frequently tested REG was used for random target selection. He reported a total of 243 subjects in 358 sessions conducted by eight experimenters (Honorton et al, 1990). Overall there were 34% hits (correct target selections), where 25% would be expected by chance (p = 4.8 x 10^-5). This is strong evidence for ESP in the ganzfeld. So far, Hyman has no complaints about the methodology.

Honorton also found that the success was concentrated in those trials where the target pictures were dynamic; ie, emotional action scenes taken from movies, as opposed to the kinds of static pictures used in most previous ganzfeld studies. The hit rate for dynamic targets was 40% (p = 4.9 x 10^-6) and only 28% for the static targets, which was not significant. He also found that results were significantly better when the sender was a friend of the subject rather than a stranger (p = .034).

Could Honorton's success be duplicated elsewhere? For a number of years, my collegue H Kanthamani has been conducting ganzfeld experiments here at the Institute for Parapsychology. Several years ago, Honorton and Ephraim Schechter (1986) reported preliminary results on 74 of their subjects who had never been previously tested in the ganzfeld. They found a 64% hit rate among 28 of these subjects who (a) practiced a mental discipline, (b) had had personal psi experiences, and (c) had a particular personality profile on the Myers-Briggs Type Indicator. Richard Broughton, Kanthamani, and Anjum Khilji (1990) looked back in their files and uncovered 120 first-timers in the ganzefeld who had been tested at our lab. 28 of these subjects fit Honorton's criteria and they had a significant hit rate of 43% (p=.03). Although lower than Honorton's 64%, this precentage still represents a significant independent confirmation of Honorton's model.