In our first study (Lau et al., 2005), we found that a significant (45%) group of participants chose the correct target. In the second study, 40% chose the correct picture, and 20% correct choices were made in our third study. Although the percent correct hits across the three studies (i.e., 35%) was greater than even the positive meta-analyses, this overall percentage was not significantly greater than chance. These conflicting results led us to conduct five more studies, obtaining correct percentages of 30%, 30%, 20%, 35%, and 40%. After eight studies, we had an overall hit rate of 32% (which agrees with the positive meta-analyses) and, in fact, our hit rate was also statistically significant, χ2(1) = 4.03, p < .05. Further, when our data are added to the Milton and Wiseman (1999) meta-analysis over ganzfeld studies, the overall percent correct responses goes from 26% to 27% and this value now is very close to significant. So, for the moment, even the evidence against humans possessing psychic powers is precariously close to demonstrating humans do have psychic powers. The lower boundary of the confidence interval is now 24.7%, which is extremely close to not including the 25% value.
http://www.deanradin.com/evidence/Delgado2005.pdf
http://www.deanradin.com/evidence/Delgado2005.pdf
Radin also gives some criticisms of their methods which were used to dismiss the effect.
We may forgive these lapses in motivational justification, for many scientists find it difficult to accept that telepathy might be true. But the next lapse is not so easily pardonable. To test their skepticism, they conducted a series of eight new
ganzfeld experiments. Their experiments resulted in a significantly positive overall hit rate of 32%, which is exactly the same hit rate found in a meta-analysis of 88 ganzfeld experiments consisting of 3,145 trials conducted from 1974 to 2004 (Radin, 2006, p. 120). One might expect that their own confirmation of the ganzfeld effect would have settled their suspicions, but instead it brought into sharp focus their actual concern: that the empirical evidence for telepathy was “precariously close to demonstrating that humans do have psychic powers”
(Delgado-Romero & Howard, 2005, p. 298). Without delving into why such evidence would be so disturbing, Delgado-Romero and Howard (2005) then introduce an ad hoc “psychic theory” (p. 298) to explain the hit rate fluctuations in their ganzfeld tests and to motivate their final, conclusive experiment. Their theory, which is stated without supporting evidence or citations, assumes that it takes two psychics to successfully send and receive telepathic information. If one or both of the pair are not psychic, then they will only achieve chance results. Based on this theory—which assumes that being psychic is a stable state, unlike virtually every other known form of human performance—
they predicted that by selecting pairs that produced a hit in a previous experiment, then running them repeatedly through a new experiment, that the resulting hit rate ought to be extremely high. Instead, they report a hit rate of only 13%, which led them to two conclusions: First, based solely on this experiment, they could now justify why they “do not believe that humans possess telepathic powers,” and second, that the highly significant hit rate estimate based on 88 previous experiments, and their own series of eight experiments, must be due to a mysterious “crud factor” (Delgado-Romero and Howard, 2005, p. 300). These conclusions are dubious because (a) they failed to report that the 13% hit rate they found in their final experiment was significantly below chance, (b) an explanation for prior results based on a theory of crud is hardly persuasive, and (c) their proposed psychic theory was unjustified and exceedingly implausible, based on previous empirical studies.
http://www.deanradin.com/evidence/Radin2007Flaws.pdf
ganzfeld experiments. Their experiments resulted in a significantly positive overall hit rate of 32%, which is exactly the same hit rate found in a meta-analysis of 88 ganzfeld experiments consisting of 3,145 trials conducted from 1974 to 2004 (Radin, 2006, p. 120). One might expect that their own confirmation of the ganzfeld effect would have settled their suspicions, but instead it brought into sharp focus their actual concern: that the empirical evidence for telepathy was “precariously close to demonstrating that humans do have psychic powers”
(Delgado-Romero & Howard, 2005, p. 298). Without delving into why such evidence would be so disturbing, Delgado-Romero and Howard (2005) then introduce an ad hoc “psychic theory” (p. 298) to explain the hit rate fluctuations in their ganzfeld tests and to motivate their final, conclusive experiment. Their theory, which is stated without supporting evidence or citations, assumes that it takes two psychics to successfully send and receive telepathic information. If one or both of the pair are not psychic, then they will only achieve chance results. Based on this theory—which assumes that being psychic is a stable state, unlike virtually every other known form of human performance—
they predicted that by selecting pairs that produced a hit in a previous experiment, then running them repeatedly through a new experiment, that the resulting hit rate ought to be extremely high. Instead, they report a hit rate of only 13%, which led them to two conclusions: First, based solely on this experiment, they could now justify why they “do not believe that humans possess telepathic powers,” and second, that the highly significant hit rate estimate based on 88 previous experiments, and their own series of eight experiments, must be due to a mysterious “crud factor” (Delgado-Romero and Howard, 2005, p. 300). These conclusions are dubious because (a) they failed to report that the 13% hit rate they found in their final experiment was significantly below chance, (b) an explanation for prior results based on a theory of crud is hardly persuasive, and (c) their proposed psychic theory was unjustified and exceedingly implausible, based on previous empirical studies.
http://www.deanradin.com/evidence/Radin2007Flaws.pdf
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