Another scandal for Psychology – Daryl Bem’s data massage

For Skeptical Inquirer, Volume 43, No. 6. November / December 2019

Note: this is the version I submitted to the magazine. It may have been edited before publication.

Susan Blackmore

In a tweet on August 16th, psychologist, Richard Landers, asked ‘who’s surprised that these paragraphs simply disappeared wholesale from Daryl Bem’s 2019 2ed revision of his chapter in Sternberg’s “Guide to publishing in Psychology”?’ The deleted parts basically amount to an endorsement of p-hacking and data massage, with Bem explicitly urging authors to ‘Go on a fishing expedition for something – anything – interesting’.

Bem is a name well known to thousands of undergraduates as a co-author of the famous “Hilgard’s Introduction to Psychology”. But he is clearly in trouble, and so he should be. These omitted paragraphs are bad enough, but he has form. In a 2017 Skeptical Inquirer 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. Only Bem still seems to think it’s OK, saying 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).

This latest scandal for psychology goes straight to my heart because of the harm Bem has done to parapsychology – and hence to the public’s beliefs about psychic phenomena. In decades of research he has claimed, again and again, that there is solid evidence for psi in the ganzfeld and, more recently, for ‘feeling the future’. This involves a type of experiment on premonition in which, it is claimed, emotional responses to images can be detected before the person sees them.

Why am I so upset about this? Because 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 and died last year. But – and here’s the important point – Bem had used Sargent’s data in his meta-analysis, 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.

I wrote a post about Landers’ tweet for my blog on Psychology Today and linked to my Facebook page. Unfortunately, the blog’s editors changed my title from “Another scandal for psychology” to “How not to find evidence of psychic phenomena’. This, as you can imagine, provoked comments asking why I didn’t review all the more recent ganzfeld work, others defending Sargent, and others – correctly – pointing out that there can be wishful thinking and data manipulation on both sides. But my point was not to drag up the Sargent ‘fraud or not’ question but to highlight the danger to psychology of Bem’s actions. I hope that exposing such dodgy practices makes future researchers less likely to indulge 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 Magazine (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.