How Not to Find Evidence of Psychic Phenomena

One of the field's most famous proponents has preached questionable practices.

Posted Aug 27, 2019

In a tweet last week, Richard Landers says he was looking at the new edition of Robert Sternberg's book about publishing in psychology journals and discovered paragraphs that are omitted from Daryl Bem's chapter in the new edition. “They are basically an endorsement of p-hacking and data massage,” he says. 

Landers' tweet about Bem
Source: Twitter

Bem is a name well known to thousands of undergraduates as a co-author of the famous “Hilgard’s Introduction to Psychology." These omitted paragraphs are bad enough, but he has form. In a 2017 article, psychologist Stuart Vyse highlighted the dangers of p-hacking – the highly dubious practice of hunting around in one’s data until you find something ‘significant’, i.e. statistically significant, preferably at the 0.5 level or better.

That dubious practice, he says, was once common but is now largely acknowledged as unacceptable. Bem has said of his past experiments “they were always rhetorical devices. I gathered data to show how my point would be made. I used data as a point of persuasion, and I never really worried about, ‘Will this replicate or will this not?’” (Engber 2017). I responded to Vyse's article with upsetting stories of my own (Blackmore 2018).

I am upset by the harm this approach has done to parapsychology, and hence to the public’s beliefs about psychic phenomena. In decades of research Bem has claimed, again and again, that there is solid evidence for psi in the ganzfeld – that is, telepathy or clairvoyance using a technique in which the ‘receiver’ lies relaxing with a pink or white visual field and white noise through headphones, while a ‘sender’ looks at photos or a video and tries to transmit images to the receiver.

In 1979 I discovered that my friend and colleague in Cambridge, Carl Sargent, was manipulating the results in his ganzfeld experiments through an unnecessarily complicated randomization procedure. The story was eventually published (Blackmore 1987, Harley and Matthews, 1987). Sargent denied fraud but quickly left the field. (He died last year.) But – and here’s the important point – Bem used Sargent’s data in his meta-analysis, with Sargent’s studies making up a quarter of those involved. Bem did not even cite the papers these data came from and certainly did not refer to my paper showing how Sargent had cheated (Bem and Honorton 1994). I have challenged Bem personally over this but he denies that it matters. The public impression was given, and remains, that psychic effects have been found when they have not.

Does this matter? Yes, very much. If true evidence for the paranormal were found the implications for the rest of science would be profound. Meanwhile, Bem’s claims for ganzfeld and other psychic effects are frequently cited as providing such evidence when they do not. So people are being badly misled, with consequences for their trust in science.

My only hope is that exposing such dodgy practices means future researchers are less like to indulge themselves in trying to prove their own beliefs rather than seeking the best explanation.


Bem, D.J. and Honorton, C. (1994) Does psi exist? Replicable evidence for an anomalous process of information transfer. Psychological Bulletin 115 4-18

Blackmore, S.J. 1987a A report of a visit to Carl Sargent’s laboratory Journal of the Society for Psychical Research 54 186-198

Blackmore, S. 2018, Daryl Bem and psi in the ganzfeld, Skeptical Inquirer,  42:1, 44-45

Engber, Daniel. 2017. Daryl Bem proved ESP is real. Which means science is broken. Slate (May 17). Accessed June 05, 2017.

Harley, T. and Matthews, G. (1987) Cheating, psi, and the appliance of science: A reply to Blackmore. Journal of the Society for Psychical Research, 54, 199-207

Vyse, S. (2017). P-hacker confessions: Daryl Bem and me. Skeptical Inquirer, 41(5), 25-27