Research supports the
notion that hypnosis can transform perception
BY MITCH LESLIE
Hypnosis can change how we
see the world, a new Stanford study has revealed. By
using PET scans to monitor neural activity, researchers
demonstrated that the brain processes visual input
differently under hypnosis allowing subjects to
"see" color when they are actually staring at a
black-and-white image. By bolstering the idea that
hypnosis transforms perception, the study supports the
use of the technique to improve athletic and intellectual
performance and even to "think away" pain.
The question of how to
interpret hypnosis divides psychiatrists into two camps,
said David Spiegel, MD, professor of psychiatry and
behavioral sciences and senior author on the study. He
and many other psychiatrists regard hypnosis as a genuine
mental state, in which our perception of reality changes
and our mind like a telephoto lens zooms in on a
subject.
But skeptics argue that
hypnosis is a form of trickery. Far from inducing a
focused mental state, it merely makes people extremely
agreeable and then they obligingly report seeing,
hearing or feeling whatever the hypnotist wants.
The disagreement persists
because testing these theories requires a way to
differentiate what people perceive from what they claim
to perceive. To identify what the brain really
"sees" during hypnosis, Spiegel and colleagues
from Harvard, Massachusetts General Hospital and Memorial
Sloan-Kettering Cancer Center in New York City used a PET
(for positron emission tomography) scanner to monitor
activity in the brain's visual areas. A PET scanner
gauges blood flow to different parts of the brain to
detect which regions are active.
Hypnotized and
unhypnotized subjects observed a colored patchwork of
squares or an identical pattern in which the squares were
shades of gray. The researchers suggested that the
subjects visualize each image as either color or
black-and white.
All the while, the PET
scanner was measuring how hard the cells in two visual
areas were working. The immediate decoding of nerve
impulses from the eyes takes place in the occipital lobe
at the back of the brain, Spiegel said. But to interpret
this raw data, the brain needs to summon up memories and
make comparisons an activity that occurs farther
forward, in the temporal lobe.
As the researchers
reported in the August issue of the American Journal of
Psychiatry, under hypnosis the brain sees what it's told
to see. When a hypnotized subject was told to visualize
the image in color, the color-processing areas in the
brain lit up regardless of whether the actual image
was color or black-and-white. And when the instructions
were to visualize the image in grays, the brain always
responded as if scanning an old black-and-white photo.
Without hypnosis, the
results were much different. The left side of the brain
always remained true to the image. The color-processing
areas only activated when the colored pattern was shown,
for example. However, the right side of the brain
responded as if hypnotized, seeing what the hypnotist
suggested instead of the true colors.
Spiegel thinks the
characteristics of the study volunteers may explain this
difference between right and left hemispheres of the
brain. All eight were "highly hypnotizable"
adults. Most of us can be hypnotized, Spiegel said, but
only about 10 percent of us have the capacity for intense
concentration and qualify as highly hypnotizable. As the
study volunteers focused on the image and tried to
mentally re-paint it, they may have slipped into a
near-hypnotic state, during which they responded to the
hypnotist's suggestions.
"This study lends
considerable weight to the idea that hypnosis is a real
neurological phenomenon," Spiegel said. "But
our goal is not just to verify a hypothesis. With
hypnosis, we can help people modulate perceptions in ways
that are therapeutically helpful."
Reducing pain through
hypnosis is one of the applications Spiegel is exploring.
In a study published last February in the Lancet, he and
his colleagues reported that self-hypnosis could ease
pain for patients receiving radiation treatment. Spiegel
and his colleagues found that the patients who learned
self-hypnosis not only reported feeling less pain, they
used half the amount of pain medication. "They are
not just suffering in silence they are able to change
their perception of pain," Spiegel said.
Hypnosis may also help
boost our performance in a number of activities, from
test-taking to sports. "Hypnosis can be very helpful
in allowing you to focus on what you want to focus
on," Spiegel said. After playing well, athletes
often claim to have been "in the zone" it's
become one of sports' most overused cliches. Yet there is
some truth in the cliche, Spiegel said. Top-flight
athletes may urge themselves into a state of heightened
focus that is close to a hypnotic state.
Spiegel recalls that one
of his students, a wide receiver on the Stanford football
team, described how, when playing well, he could exclude
everything from his mind except two things: the ball and
the defender covering him. That's a formidable act of
concentration, considering that "he's running around
on the field with 20 other large guys," Spiegel
said.
Spiegel's collaborators on
the study were Stephen Kosslyn, PhD; William Thompson;
Maria Costantini-Ferrando, PhD; and Nathaniel Alpert,
PhD.
A grant from the Mind/Body
Research Network of the John D. and Catherine T.
MacArthur Foundation supported the work. SR
|
