History of the ganzfeld experiment

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The ganzfeld is a method of sensory deprivation devised in the late 1920's by the psychologist Wolgang Metzger. The name "ganzfeld" is German for "total field" and it works by presenting the subject with wholly uniform sensory stimuli, and then asking the subject what they see. Most commonly this is achieved by placing half ping-pong balls over the subject’s eyes, and headphones playing white noise (static) over the ears.

In the mid 1970's this technique was used by parapsychologists to see if it was conducive to ESP. Charles Honorton, at the Maimonides Laboratory, had recently claimed good results with his investigation into ESP and dreams but was frustrated by the amount of time it took to complete one trial. The ganzfeld was adopted because it was quicker and was considered to prompt a hypnogogic-like state in the user where ESP could function. Thus, while the subject (or "receiver") was under the ganzfeld state, another person would be looking at a target (usually a photograph or videoclip). After half an hour the subject would be given the target along with a number of decoys and asked to choose which one was most like the images they saw. Typically, there are three decoys along with the target, giving a score expected by chance of 25%.

The ganzfeld soon became a popular choice as a protocol to test for psi and it has remained in constant use since the first experiment was published in 1974. The evidence in favour of psi in the ganzfeld is usually split into three sections: 1974-1982 (Honorton's 1985 meta-analysis); 1982-1989 (Honorton's results from his Psychophysical Research Laboratory);1991-1999 (Bem, Broughton and Palmer's meta-analysis).

1974-1982

The early stage of research using the ganzfeld was notable for deviations in protocol, and debates (sometimes rather heated) on how to interpret some of the results emerging from laboratories in the USA and Europe.

The most famous of these was the episode between Susan Blackmore and Carl Sargent. Blackmore visited Sargent's laboratories at Cambridge, hoping to discover why they had had such success with their investigations into ESP while she'd had none. During this visit she noticed a number of irregularities in the cumbersome randomisation process and wondered if these could account for the results. She wrote a paper on the matter in 1980 that was held in the library of the Society for Psychical Research until 1987 when it was published in the society's journal, along with other criticisms from Parker and Wiklund and rebuttals from Sargent, Harley and Matthews. The episode lead to Sargent leaving parapsychology, saying that "If I learned one thing in parapsychology, it is that results and statistics and data never changed anyone's mind about anything; experience is the only arbiter." (Sargent, "Sceptical Fairytales From Bristol", JSPR, 54)

In 1985 Ray Hyman, a sceptic, and Charles Honorton, a parapsychologist, contributed two articles to issue 49 of the Journal of Parapsychology, examining the database of 42 experiments from 1974 until 1982. Hyman criticised the experiments for a number of flaws such as handling cues (giving the subject the same photo that was used by the sender), multiple analysis (using several scoring systems and reporting only one), and poor randomisation. Honorton agreed that multiple analysis was a problem and so limited himself to those which used the same scoring system: the "direct hit" method, as described in the second paragraph above. He found that the overall score for these 28 experiments was 38% (25% expected by chance), and this score was far too high to be accounted for by Hyman's flaws.

Honorton's database contains 839 trials, whereas the unused experiments have 1,752 (plus a further six experiments of 369 trials in total that were never included in the database). The results of the non-analysed experiments are at chance, and putting the two databases together brings down the overall hit rate to 29%.

In the following issue of the Journal of Parapsychology, Hyman and Honorton collaborated on an article, "A Joint Communique", in which they defined how they thought future experiments using the ganzfeld procedure should be conducted and reported. This ushered in what is generally considered the second phase of research into the ganzfeld

1982-1989

Although Hyman and Honorton's "Joint Communique" was published in 1986, Honorton had already been thinking about how to improve the ganzfeld procedure. Having established, in 1979, the Psychophysical Research Laboratory, he designed a new ganzfeld procedure which used computers wherever possible in order to automate the method and lessen the possibility of fraud.

The experiments using this procedure, called “autoganzfeld”, began in 1982. For the next seven years, until the laboratory closed, eleven experiments were begun using this apparatus. At the end, they had completed 354 trials with a hit rate of 34%, whereas 25% would be expected by chance.

This replication of Honorton’s previous findings was a major triumph, especially considering it was conducted under much stricter conditions. Nevertheless, criticisms were raised over the protocol. One of which was that the targets, both dynamic and static, were stored on VHS video tape. The target was played repeatedly, so that during the half hour of sending the one-minute clip would’ve been used dozens of times. This would have an effect on the quality of image, and this could be detected by the receiver and/or experimenter as they viewed the same video clips during the judging procedure. Hyman pointed out that all the above-chance scores came from second or subsequent appearances of a target, and Wiseman noted that trials where the experimenter helped with the judging scored significantly higher than those where the experimenter wasn’t present.

Also this level of success needs to be balanced with the lack of success of other experiments completed by other laboratories during this period. 17 experiments, totalling 768 trials, found results only a little above chance. These results have largely been ignored by parapsychological literature. Combining the PRL trials with other ganzfeld work completed at that time gives an overall hit rate of around 29%.

1991-1999

The experiments conducted during this time were fairly comprehensively covered by two meta-analyses. The first, by Milton and Wiseman, set out to see if the Joint Communique by Hyman and Honorton had had an effect on results. To this end they decided to analyse all experiments begun after the start of 1987 (they decided the parapsychological community needed a year for 1986's Joint Communique to make a difference) and they set the deadline at February 1997.

The result of their meta-analysis was an overall hit rate of 27%. This came in for immediate criticism, especially since just after the deadline and long before publication Dalton released the results from her highly successful experiment concerning creative subjects in the ganzfeld. This experiment alone would’ve pushed the overall hit rate up to 29%.

Another criticism was that the meta-analysis contained experiments that deviated too much from the typical ganzfeld set-up. To examine if this made a difference, Bem, Broughton and Palmer conducted another meta-analysis, this time including work published after the 1997 deadline, and ordering them according to “standardness” (by giving the methods, without results, to blind judges along with pre-existing descriptions of the ganzfeld procedure). They found that “standard” experiments scored higher than “non-standard”: 31% as opposed to 24%.

Whether this is a replication of the earlier work or not is debatable, since no similar analysis has been carried out on pre-1991 work, and the deviations in protocol of the pre-Joint Communique work are perhaps even wider.

2000-2005

Since then, there’ve been no further meta-analyses concerning the ganzfeld. Work continues, and the methods involved have diverged yet further. The main advance has been the introduction of computer controlled experiments, with the video clips and pictures stored on hard drive as opposed to tape. These refinements haven’t improved the results which are at chance, with a hit rate of approximately 27% after 20 experiments.

Selected references

Honorton, Harper, “Psi-mediated imagery and ideation in an experimental procedure for regulating perceptual input”, Journal of the American Society for Psychical Research, 68, 1974

Hyman, “The Ganzfeld Psi Experiment: A critical appraisal”, Journal of Parapsychology 49, 1985

Honorton, "Meta-analysis of ganzfeld research: a response to Hyman", Journal of Parapsychology 49, 1985

Hyman, Honorton, "The Joint Communique", Journal of Parapsychology 50, 1986

Blackmore, “A Report of a Visit to Carl Sargent's Laboratory”, Journal of the Society for Psychical Research, 1987

Harley, Matthews, “Cheating, psi and the appliance of science: a reply to Blackmore”, JSPR, 1987

Sargent, “Sceptical Fairytales from Bristol”, JSPR, 1987

Parker, Wiklund, “The Ganzfeld Experiments: towards an assessment”, Journal of Parapsychology, 1987

Honorton, Berger, Varvoglis, Quant, Derr, Schechter, Ferrari, “Psi Communication in the ganzfeld: experiments with an automated testing system and a comparison with a meta-analysis of earlier studies”, Journal of Parapsychology 54, 1990

Bem, Honorton, "Does Psi Exist?" Replicable Evidence for an Anomalous Process of Information Transfer, Psychological Bulletin, 1994

Milton, Wiseman, “Does Psi Exist? Lack of Replication of an Anomalous Process of Information Transfer”, Psychological Bulletin, 1999

Parker, "A Review of the Ganzfeld Work at Gothenburg University" (pdf file), Journal of the Society of Psychical Research 64, 2000

Bem, Palmer, Broughton, "Updating the Ganzfeld Database: A Victim of Its Own Success?" (pdf file), Journal of Parapsychology 65, 2001

Palmer, "ESP in the Ganzfeld: Analysis of a debate", Journal of Consciousness Studies, 2003

For more details and references, please see:

“A history of psi in the ganzfeld, part 1 1974-1982”, 2005

"A history of psi in the ganzfeld, parts 2-4, 1983-1990", 2005

Part or all of this page was copied from Skepticwiki

References