Does Psi exist? Lack of replication of an anomalous process of information transfer

D. J. Bem and C. Honorton (1994) recently presented in this journal a set of ganzfeld extrasensory perception (ESP) experiments conducted by C. Honorton that appeared to support the existence of a communication anomaly. In this article, the authors present a meta-analysis of 30 ganzfeld ESP studies from 7 independent laboratories adhering to the same stringent methodological guidelines that C. Honorton followed. The studies failed to confirm his main effect of participants scoring above chance on the ESP task, Stouffer z = 0.70, p = .24, one-tailed; M effect size (z/N1/2) = 0.013, SD = 0.23. The new studies included replication attempts of 3 out of 5 internal effects reported as statistically significant by D. J. Bem and C. Honorton. Only 1 was confirmed, and the authors found that D. J. Bem and C. Honorton were mistaken in describing the original effect as being statistically significant. The authors conclude that the ganzfeld technique does not at present offer a replicable method for producing ESP in the laboratory.