Can the future affect the past? A distinguished psychologist appears to be saying it can, according to a New York Times report of controversy over a forthcoming paper:
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."
Without reading a paper in press -- and without the statistical expertise needed to judge it professionally -- I can't say anything about the underlying research. But the Times article raises some interesting points.
1) This isn't the first case of a respected scientist finding evidence for effects considered pseudoscience by his or her peers. Indeed, the author of the Times article also reported a few years ago on the end of the Princeton Engineering Anomalies Research Laboratory (PEAR). The English biologist Dr. Rupert Sheldrake held a prestigious Royal Society Research Fellowship before leaving conventional research to pursue theories of "morphic resonance." The French statisticians Michel Gauquelin and Françoise Schneider-Gauquelin found limited but significant astrological influences in the careers of championship athletes.
2) The mass popularity of the paranormal probably hurts unorthodox research more than it helps. Isaac Asimov once amended a dictum of his fellow scientist-novelist Arthur C. Clarke about the scientific establishment's view on what is possible to read: "When the lay public rallies round to an idea that is denounced by distinguished elderly scientists and supports the idea with great fervor and emotion, the distinguished but elderly scientists are then, after all, right." So both the enthusiasm of the laity and the (probably necessary) skeptical zeal of professionals may only help the other side.
3) Some controversial results still haven't been discounted as observational or statistical error. In a review of questionable science, the Dutch astronomer and skeptic Cornelis de Jager, for example, acknowledged that further research had confirmed that outstanding athletes were more likely to have been born under Mars.
Dr. Bem's phrase about "using more talented people" sounds tongue-in-cheek to me, especially since no psychic has been able to claim the million dollars offered by the James Randi Educational Foundation for a successful demonstration. But even if the experiment can be replicated, it's important to be open to other explanations besides ESP. And Dr. de Jager's take on the Gauquelins offers a clue. Natal astrology may appear to work because there may be statistically optimal times of the year for birth and early development in humans as in other animals. (So far the best known of these are artifacts of the school year and athletic eligibility rules, not necessarily underlying ability.)
Since the results aren't terribly strong and haven't been replicated, the most likely explanation is the kind of statistical issue mentioned by the sources. This seems to me more likely than a total revision of all physical law. But shouldn't we be open to some third, significant if less drastic possibility? You never know where an anomaly might lead. To quote Isaac Asimov again: "The most exciting phrase to hear in science, the one that heralds the most new discoveries, is not 'Eureka!' (I found it!) but 'Hmmm ... that's funny....'"