Does Psi Exist? Comments on Milton and Wiseman's (1999) Meta-Analysis of Ganzfeld Research

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Plain English Summary

In 1999, two researchers declared the ganzfeld telepathy experiment — where someone in sensory deprivation tries to receive mental images from a sender — was a bust. Storm and Ertel disagreed. They assembled 79 studies spanning nearly three decades and found people guessed the right image 31% of the time when chance predicts 25%. That gap sounds modest, but the odds of it being a fluke were less than one in a billion. This telepathy-like effect appeared in every subset of studies, including the very batch skeptics used to declare it dead. Their verdict: the ganzfeld reliably produces anomalous communication, and the negative conclusion came from too small a slice of the evidence.

Abstract

J. Milton and R. Wiseman (1999) attempted to replicate D. Bern and C. Honorton's (1994) meta-analysis. which yielded evidence that the ganzfeld is a suitable method for demonstrating anomalous communication. Using a database of 30 ganzfeld and autoganzfeld studies, Milton and Wiseman's meta-analysis yielded an effect size (£5) of only 0.013 (Stouffer Z = 0.70, p = .24. one-tailed). Thus they failed to replicate Bern and Honorton's finding (ES = 0.162, Stouffer Z = 2.52, p = 5.90 X 10~\ one-tailed). The authors conducted stepwise performance comparisons between all available databases of ganzfeld research, which were argued not to be lacking in quality. Larger aggregates of such studies were formed, including a database comprising 79 ganzfeld-autoganzfeld studies (ES = 0.138. Stouffer Z = 5.66. p = 7.78 x \(y9). Thus Bern and Honorton's positive conclusion was confirmed. More accurate population parameters for the ganzfeld and autoganzfeld domains were calculated. Significant bidirectional psi effects were also found in all databases. The ganzfeld appears to be a replicable technique for producing psi effects in the laboratory.