by Peter Aldhous
11 November 2010
Extraordinary claims don't come much
more extraordinary than this: events that haven't yet happened can
influence our behavior.
Parapsychologists have made outlandish claims about precognition -
knowledge of unpredictable future events - for years. But the fringe
phenomenon is about to get a mainstream airing: a paper providing
evidence for its existence has been accepted for publication by the
leading social psychology journal.
What's more, skeptical psychologists who have pored over a
of the paper say they can't find any significant flaws.
"My personal view is that this is
ridiculous and can't be true," says
Joachim Krueger of
Brown University in Providence, Rhode Island, who has
about the work on the Psychology Today website.
"Going after the methodology and the
experimental design is the first line of attack. But frankly, I
didn't see anything. Everything seemed to be in good order."
The paper, due to appear in the
Journal of Personality and Social
Psychology before the end of the year, is the culmination of eight
years' work by
Daryl Bem of Cornell University in Ithaca, New
"I purposely waited until I thought
there was a critical mass that wasn't a statistical fluke," he
It describes a series of experiments
involving more than 1000 student volunteers.
In most of the tests, Bem took
well-studied psychological phenomena and simply reversed the
sequence, so that the event generally interpreted as the cause
happened after the tested behavior rather than before it.
In one experiment, students were shown a list of words and then
asked to recall words from it, after which they were told to type
words that were randomly selected from the same list. Spookily, the
students were better at recalling words that they would later type.
In another study, Bem adapted research on "priming" - the effect of
a subliminally presented word on a person's response to an image.
For instance, if someone is momentarily flashed the word "ugly", it
will take them longer to decide that a picture of a kitten is
pleasant than if "beautiful" had been flashed.
Running the experiment back-to-front,
Bem found that the priming effect seemed to work backwards in time
as well as forwards.
Exploring time-reversed versions of established psychological
phenomena was "a stroke of genius", says the skeptical Krueger.
Previous research in parapsychology has
used idiosyncratic set-ups such as
Ganzfeld experiments, in which
volunteers listen to
white noise and are presented with a uniform
visual field to create a state allegedly conducive to effects
including clairvoyance and telepathy. By contrast, Bem set out to
provide tests that mainstream psychologists could readily evaluate.
The effects he recorded were small but statistically significant. In
another test, for instance, volunteers were told that an erotic
image was going to appear on a computer screen in one of two
positions, and asked to guess in advance which position that would
be. The image's eventual position was selected at random, but
volunteers guessed correctly 53.1 per cent of the time.
That may sound unimpressive - truly random guesses would have been
right 50 per cent of the time, after all.
But well-established phenomena such as
the ability of low-dose aspirin to prevent heart attacks are based
on similarly small effects, notes
Melissa Burkley of Oklahoma
State University in Stillwater, who has
also blogged about Bem's
work at Psychology Today.
Respect for a
So far, the paper has held up to scrutiny.
"This paper went through a series of
reviews from some of our most trusted reviewers," says
Judd of the University of Colorado at Boulder, who heads the
section of the Journal of Personality and Social Psychology
editorial board that handled the paper.
Indeed, although Bem is a self-described
"maverick" with a long-standing interest in paranormal phenomena, he
is also a respected psychologist with a reputation for running
He is best known for the theory of
self-perception, which argues that people infer their attitudes from
their own behavior in much the same way as they assess the attitudes
Bem says his paper was reviewed by four experts who proposed
amendments, but still recommended publication.
Still, the journal
will publish a skeptical editorial commentary alongside the paper,
"We hope it spurs people to try to
replicate these effects."
One failed attempt at replication has
already been posted online.
In this study,
Jeff Galak of
Carnegie Mellon University in Pittsburgh, Pennsylvania, and
Nelson of the University of California, Berkeley, employed an online
Consumer Behavior Lab in an effort to repeat Bem's
findings on the recall of words.
Bem argues that online surveys are inconclusive, because it's
impossible to know whether volunteers have paid sufficient attention
to the task. Galak concedes that this is a limitation of the initial
study, but says he is now planning a follow-up involving student
volunteers that will more closely repeat the design of Bem's
This seems certain to be just the first exchange in a lively debate:
Bem says that dozens of researchers have already contacted him
requesting details of the work.