Here's a fascinating new scientific paper now in press in the Journal of Personality and Social Psychology: "Feeling the Future", by Daryl Bem of Cornell University (download a copy of the article as a PDF.)
Bem notes that recent research in psi has moved from explicit forced-choice guessing tasks to experiments using subliminal stimuli and indirect, physiological responses. One of the areas of research providing curious results - pioneered by Dean Radin in 1997 (not, as Randi claimed in 2008, Radin's "latest distraction") - investigates “presentiment”:
[P]hysiological indices of participants’ emotional arousal are monitored as they view a series of pictures on a computer screen. Most of the pictures are emotionally neutral; but, on randomly selected trials, a highly arousing negative or erotic image is displayed. As expected, strong emotional arousal occurs when these images appear on the screen, but the remarkable finding is that the increased arousal is observed to occur a few seconds before the picture appears, before the computer has even selected the picture to be displayed. The presentiment effect has also been demonstrated in an fMRI experiment that monitored brain activity (Bierman & Scholte, 2002) and in experiments using bursts of noise rather than visual images as the arousing stimuli (Spottiswoode & May, 2003). [emphasis added]
Bem then reports on nine experiments carried out at Cornell, involving more than 1,000 participants, that "test for retroactive influence by “timereversing” well-established psychological effects so that the individual’s responses are obtained before the putatively causal stimulus events occur." All but one of them yielded statistically significant results. Additionally, "the individual-difference variable of stimulus seeking, a component of extraversion, was significantly correlated with psi performance in 5 of the experiments, with participants who scored above the midpoint on a scale of stimulus seeking achieving a mean effect size of .42."
The article also discusses skepticism about psi effects, theories of psi, and issues of statistical analysis and replication. Plus it ends with a fun comment:
Near the end of her encounter with the White Queen, Alice protests that “one can’t believe impossible things,” a sentiment with which the 34% of academic psychologists who consider psi to be impossible would surely agree. The White Queen famously retorted, “I daresay you haven’t had much practice. When I was your age, I always did it for half-an-hour a day. Why, sometimes I’ve believed as many as six impossible things before breakfast”.
Unlike the White Queen, I do not advocate believing impossible things. But perhaps this article will prompt the other 66% of academic psychologists to raise their posterior probabilities of believing at least one anomalous thing before breakfast.