BENEDICT CAREY “Journal’s Article on ESP Expected to Prompt Outrage”

コーネル大学名誉教授Daryl J. Bem*1のESPの存在を〈実証〉したと主張する論文がJournal of Personality and Social Psychologyの査読を通り、同誌に掲載されることが決定し、それが論議の的となっている*2

The paper describes nine unusual lab experiments performed over the past decade by its author, Daryl J. Bem, an emeritus professor at Cornell, testing the ability of college students to accurately sense random events, like whether a computer program will flash a photograph on the left or right side of its screen. The studies include more than 1,000 subjects.

Some scientists say the report deserves to be published, in the name of open inquiry; others insist that its acceptance only accentuates fundamental flaws in the evaluation and peer review of research in the social sciences.


In an interview, Dr. Bem, the author of the original paper and one of the most prominent research psychologists of his generation, said he intended each experiment to mimic a well-known classic study, “only time-reversed.”

In one classic memory experiment, for example, participants study 48 words and then divide a subset of 24 of them into categories, like food or animal. The act of categorizing reinforces memory, and on subsequent tests people are more likely to remember the words they practiced than those they did not.

In his version, Dr. Bem gave 100 college students a memory test before they did the categorizing — and found they were significantly more likely to remember words that they practiced later. “The results show that practicing a set of words after the recall test does, in fact, reach back in time to facilitate the recall of those words,” the paper concludes.

In another experiment, Dr. Bem had subjects choose which of two curtains on a computer screen hid a photograph; the other curtain hid nothing but a blank screen.

A software program randomly posted a picture behind one curtain or the other — but only after the participant made a choice. Still, the participants beat chance, by 53 percent to 50 percent, at least when the photos being posted were erotic ones. They did not do better than chance on negative or neutral photos.

“What I showed was that unselected subjects could sense the erotic photos,” Dr. Bem said, “but my guess is that if you use more talented people, who are better at this, they could find any of the photos.”


Many statisticians say that conventional social-science techniques for analyzing data make an assumption that is disingenuous and ultimately self-deceiving: that researchers know nothing about the probability of the so-called null hypothesis.

In this case, the null hypothesis would be that ESP does not exist. Refusing to give that hypothesis weight makes no sense, these experts say; if ESP exists, why aren’t people getting rich by reliably predicting the movement of the stock market or the outcome of football games?

Instead, these statisticians prefer a technique called Bayesian analysis, which seeks to determine whether the outcome of a particular experiment “changes the odds that a hypothesis is true,” in the words of Jeffrey N. Rouder, a psychologist at the University of Missouri who, with Richard D. Morey of the University of Groningen in the Netherlands, has also submitted a critique of Dr. Bem’s paper to the journal.

Physics and biology, among other disciplines, overwhelmingly suggest that Dr. Bem’s experiments have not changed those odds, Dr. Rouder said.

なお、Jeffrey N. Rouderと Richard D. MoreyがJournal of Personality and Social Psychologyに投稿した”An Assessment of The Evidence For Feeling The Future With A Discussion of Bayes Factor and Signi ficance Testing”*4の要旨は以下の通り;

We provide a statistical assessment of the claim that people can feel the future from the results provided in Bem (in press). Conventional signifi cance testing is particularly
ill-suited for assessing the evidence for competing positions because it may not be used to state evidence for the null hypothesis, and, consequently, is biased to overstate the evidence against it. Bayes factors, in contrast, serve as well-calibrated measures of relative evidence for two competing theoretical position, which, in this case, are that feeling-the-future hypothesis holds or does not. Bayes factors describe how researchers should update their prior beliefs about the odds of hypotheses in light of data. We find the evidence that people can feel the future with neutral and erotic stimuli to be slight, with Bayes factors of 3.23 and 1.57, respectively. There is, however, a surprising degree of evidence for the hypothesis that people can feel the future with emotionally-valenced nonerotic stimuli, with a Bayes factor of about 40. Though this value is certainly noteworthy, it is several orders of magnitude lower than what is required to overcome appropriate skepticism of such implausible claims. Moreover, this value serves as an upper bound on evidence as no corrections are made for the exploratory nature of the comparisons or the possible unreported studies that fail to find feeling-the-future effects.


*2:この論文”Feeling the Future: Experimental evidence for anomalous retroactive influences on cognition and affect”は既にベム氏のサイトから読むことができる:

*3:See also