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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Ganzfeld experiment | 2/4 | https://en.wikipedia.org/wiki/Ganzfeld_experiment | reference | science, encyclopedia | 2026-05-05T09:20:07.932209+00:00 | kb-cron |
In 1982, Honorton had started a series of "autoganzfeld experiments", that is ganzfeld experiments controlled by a computer, at his Psychophysical Research Laboratories (PRL). The trials continued until September 1989 and in 1990 Honorton et al. published the results of 11 autoganzfeld experiments they claimed met the standards specified by Hyman and Honorton (1986). In these experiments, 240 participants contributed 329 sessions. Hyman analyzed these experiments and wrote they met most, but not all of the "stringent standards" of the joint communiqué. He expressed concerns with the randomization procedure, the reliability of which he was not able to confirm based on the data provided by Honorton's collaborator, Daryl Bem. Hyman further noted that although the overall hit rate of 32% (7% higher than the 25% expectation from randomness) was significant, the hit rate for static targets (pictures) was, in fact, consistent with random and therefore inconsistent with Honorton's previous claims of positive results from the ganzfeld experiments that were conducted prior to 1982. The significance of the results was due entirely to a new set of "dynamic targets" (videos) that participants were able to identify at a rate that was better than random. In the hit rates regarding these dynamic targets, however, patterns were evident that implied visual cues were leaked:
The most suspicious pattern was the fact that the hit rate for a given target increased with the frequency of occurrence of that target in the experiment. The hit rate for the targets that occurred only once was right at the chance expectation of 25%. For targets that appeared twice the hit rate crept up to 28%. For those that occurred three times it was 38%, and for those targets that occurred six or more times, the hit rate was 52%. Each time a videotape is played its quality can degrade. It is plausible then, that when a frequently used clip is the target for a given session, it may be physically distinguishable from the other three decoy clips that are presented to the subject for judging. Hyman wrote these studies were an improvement over their older counterparts, but were not a successful replication of the ganzfeld experiments, nor a confirmation of psi. He concluded the autoganzfeld experiments were flawed because they did not preclude the possibility of sensory leakage. Richard Wiseman published a paper discussing a non-psi hypothesis based on possible sender to experimenter acoustic leakage in the autoganzfeld to account for the results. David Marks has written "Wiseman and his colleagues identified various different ways in which knowledge of the target could have been leaked to the experimenter. These included cues from the videocassette recorder and sounds from the sender who, of course, knew the target's identity... their conclusions provide little reassurance that sensory cueing of the experimenter was in any way substantially blocked." Milton and Wiseman (1999) carried out a meta-analysis of ganzfeld experiments in other laboratories. They found no psi effect; the results showed no effect greater than chance from a database of 30 experiments and a non-significant Stouffer Z of 0.70. Lance Storm and Suitbert Ertel (2001) published a meta-analysis of 79 studies published between 1974 and 1996 and concluded the positive statistically significant overall outcome indicates a psi effect. In response, Milton and Wiseman (2001) wrote the meta-analysis of Storm and Ertel was not an accurate quantitative summary of ganzfeld research as they had included early studies which had been widely recognized as having methodological problems which make it impossible to interpret the results as evidence of a psi effect. Another meta-analysis was conducted by Daryl Bem, John Palmer, and Richard Broughton in which the experiments were sorted according to how closely they adhered to a pre-existing description of the ganzfeld procedure including some experiments that had been published in the time since Milton and Wiseman's deadline. They obtained results that were significant with a Stouffer Z of 2.59, but their detractors maintained their selection of studies for inclusion was problematic.
=== Contemporary research === The ganzfeld experiment has continued to be refined over the years. In its current incarnation, an automated computer system is used to select and display the targets ("digital autoganzfeld"). This has the potential to overcome some of the shortcomings of earlier experimental setups, such as randomization and experimenter blindness with respect to the targets. In 2010, Lance Storm, Patrizio Tressoldi, and Lorenzo Di Risio analyzed 29 ganzfeld studies from 1997 to 2008. Of the 1,498 trials, 483 produced hits, corresponding to a hit rate of 32.2%. This hit rate is statistically significant with p < .001. Participants selected for personality traits and personal characteristics thought to be psi-conducive were found to perform significantly better than unselected participants in the ganzfeld condition. Hyman (2010) published a rebuttal to Storm et al. concluding that the ganzfeld studies have not been independently replicated and had thus failed to produce evidence for psi. According to Hyman, "reliance on meta-analysis as the sole basis for justifying the claim that an anomaly exists and that the evidence for it is consistent and replicable is fallacious. It distorts what scientists mean by confirmatory evidence." Storm et al. published a response to Hyman claiming the ganzfeld experimental design has proved to be consistent and reliable but parapsychology is a struggling discipline that has not received much attention so further research on the subject is necessary. Rouder et al. in 2013 wrote that critical evaluation of Storm et al.'s meta-analysis reveals no evidence for psi, no plausible mechanism, and omitted replication failures. A 2016 paper examined questionable research practices in the ganzfeld experiments and simulated how such practices could cause erroneous positive results.
== Criticism ==
There are several common criticisms of some or all of the ganzfeld experiments: