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Electrical
Brainstorms Busted as Source of Ghosts
by
Roxanne Khamsi
Published
online: 09 December 2004
Studies
showing that magnetic stimulation of the brain induces spiritual
experiences are being queried by researchers who cannot reproduce
key results. If the traditional theory is wrong, scientists will be
left struggling to explain how such thoughts and sensations are
generated.
In
the past, scientists have claimed that religious or out-of-body
experiences result from excessive bursts of electrical activity in
the brain. In the 1980s, Michael Persinger, a neuroscientist at the
Laurentian University in Ontario, Canada, began exploring this idea
through a series of experiments.
Participants
wore helmets that targeted their temporal lobes with weak magnetic
fields, of roughly the same strength as those generated by a
computer monitor. Persinger found that this caused 80% of the people
he tested to feel an unexplained presence in the room.
Persinger
suggested that magnetism causes bursts of electrical activity in the
temporal lobes of the brain, and he linked this to the spiritual
experiences.
Blinding
science
A
group of Swedish researchers has now repeated the work, but they say
their study involves one crucial difference. They ensured that
neither the participants nor the experimenters interacting with them
had any idea who was being exposed to the magnetic fields, a
'double-blind' protocol.
Without
such a safeguard, "people in the experimental group who are
highly suggestible would pick up on cues from the experimenter and
they would be more likely to have these types of experiences,"
says Pehr Granqvist of Uppsala University, who led the research
team.
Beyond
the double-blind aspect, Granqvist says the nuts and bolts of the
experiment mirrored those conducted in the past. He and his
colleagues tested 43 undergraduate students by exposing them to
magnetic fields that ranged from 3 to 7 microtesla and were aimed
just above and in front of the ears, to target the temporal lobes.
They
also tested a control group of 46 volunteers who wore the helmet but
were not exposed to the magnetic field. The volunteers were then
asked to complete questionnaires about what they experienced during
each session. The researchers report their results online in
Neuroscience Letters1.
Strong
spirits
In
contrast to the results from Persinger and others, the team found
that the magnetism had no discernable effects. Two out of the three
participants in the Swedish study that reported strong spiritual
experiences during the study belonged to the control group, as did
11 out of the 22 who reported subtle experiences.
Granqvist
acknowledges that this seems to be quite a high level of spiritual
experiences overall, but says that it matches the level that
Persinger saw in his control groups.
The
researchers say they do not know what neurological mechanism could
be generating the experiences. However, using personality tests they
did find that people with an orientation toward unorthodox
spirituality were more likely to feel a supernatural presence, as
were those who were, in general, more suggestible.
Field
defense
Persinger,
however, takes issue with the Swedish attempts to replicate his
work. "They didn't replicate it, not even close," he says.
He argues that the Swedish group did not expose the subjects to
magnetic fields for long enough to produce an effect. He also
stresses that some of his studies were double blinded. Although the
experimenters knew when the magnetic field was being applied, he
says that they did not know what effect the field was expected to
induce.
Susan
Blackmore, a psychologist based in Bristol, UK, is also reluctant to
give up on the theory just yet. She has firsthand experience of
Persinger's methods. "When I went to Persinger's lab and
underwent his procedures I had the most extraordinary experiences
I've ever had," she says. "I'll be surprised if it turns
out to be a placebo effect."
She
too thinks that the Swedish researchers may have used magnetic
fields that varied subtly from those of Persinger. "But
double-blind experiments will ultimately give us the final
answer," she says.
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