It took eight years and nine experiments with more 1,000 participants, but the results offer evidence that humans have some ability to anticipate the future.
"Of the various forms of ESP or psi, as we call it, precognition has always most intrigued me because it's the most magical," said Daryl Bem, professor of psychology emeritus, whose study will be published in the American Psychological Association's Journal of Personality and Social Psychology sometime next year.
"It most violates our notion of how the physical world works. The phenomena of modern quantum physics are just as mind-boggling, but they are so technical that most non-physicists don't know about them," said Bem, who studied physics before becoming a psychologist.
Publishing on this topic has gladdened the hearts of psi researchers but stumped doubting social psychologists, who cannot fault Bem's mainstream and widely accepted methodology. Bem became interested in the scientific study of psi (unexplained processes of information or energy transfer) when he was asked to find methodological flaws in one psi researcher's successful extrasensory perception studies -- and couldn't.
"The research and this article are specifically targeted to my fellow social psychologists," Bem said. "I designed the experiments to be persuasive, simple and transparent enough to encourage them to try replicating these experiments for themselves." Bem's innovation in the experiments reported in the article was to "take well-known phenomena in psychology and reverse their time course."
Rather than present a stimulus and measure a subject's response, Bem measured the subject's response before the stimulus was presented. In some earlier experiments by other psi researchers, participants were hooked up to physiological measuring equipment similar to a lie detector that measured emotional arousal. They sat before a computer and watched randomly selected images; some were erotic or very negative ("like the bloody photos you see on CSI") images.
"Your physiology jumps when you see one of those pictures after watching a series of landscapes or neutral pictures," Bem said. "But the remarkable finding is that your physiology jumps before the provocative picture actually appears on the screen -- even before the computer decides which picture to show you. What it shows is that your physiology can anticipate an upcoming event even though your conscious self might not."
Bem's nine experiments demonstrated similar unconscious influences from future events. For example, in one experiment, participants saw a list of words and were then given a test in which they tried to retype as many of the words as they could remember. Next, a computer randomly selected some of the words from the list and gave the participants practice exercises on them. When their earlier memory test results were checked, it was found that they had remembered more of the words they were to practice later than words they were not going to practice. In other words, the practice exercises had reached back in time to help them on the earlier test.
All but one of the nine experiments confirmed the hypothesis that psi exists. The odds against the combined results being due to chance or statistical flukes are about 74 billion to 1, according to Bem.
Throughout his career Bem has taken paths less traveled. In 1994 he co-authored a series of experiments on telepathy published in another APA journal, the Psychological Bulletin. "In my work, I have always pursued problems or puzzles that strike me as interesting and have not worried about how it might affect my career. I have a maverick approach to many psychological topics, and I consider myself fortunate that Cornell has always given me the freedom to do that."
Bem, who came to Cornell in 1978 and retired in 2007, said it is unusual for him to work on one topic for eight years, "but this one was a biggie and seemed like an appropriate thing to end my career with. The journal in which it will appear is the same journal that published my very first article 50 years ago."
Bem said he conducted the experiments because he believed that existing research strongly implied that precognition is real. "I went in optimistic that I would be able to find it with these experiments," he said. "After I started getting positive results, my undergraduate research team seemed puzzled by my enthusiasm and said, 'But didn't you tell us you thought these would work?'
"I said yes, but when I actually see them work, that's very different."