"This Is Your
Under Hypnosis" by Sandra Blakeslee.
Here's the article:
Hypnosis, with its long and checkered history in medicine and
is receiving some new respect from neuroscientists. Recent brain
people who are susceptible to suggestion indicate that when they act on
suggestions their brains show profound changes in how they process
information. The suggestions, researchers report, literally change what
people see, hear, feel and believe to be true.
The new experiments, which used brain imaging, found that people who
hypnotized "saw" colors where there were none. Others lost the ability
make simple decisions. Some people looked at common English words and
thought that they were gibberish.
"The idea that perceptions can be manipulated by expectations" is
fundamental to the study of cognition, said Michael I. Posner, an
professor of neuroscience at the University of Oregon and expert on
attention. "But now we're really getting at the mechanisms."
Even with little understanding of how it works, hypnosis has been used
medicine since the 1950's to treat pain and, more recently, as a
for anxiety, depression, trauma, irritable bowel syndrome and eating
There is, however, still disagreement about what exactly the hypnotic
is or, indeed, whether it is anything more than an effort to please the
hypnotist or a natural form of extreme concentration where people
oblivious to their surroundings while lost in thought.
Hypnosis had a false start in the 18th century when a German physician,
Franz Mesmer, devised a miraculous cure for people suffering all manner
unexplained medical problems. Amid dim lights and ethereal music played
glass harmonica, he infused them with an invisible "magnetic fluid"
only he was able to muster. Thus mesmerized, clients were cured.
Although Dr. Mesmer was eventually discredited, he was the first person
show that the mind could be manipulated by suggestion to affect the
historians say. This central finding was resurrected by Dr. James
English ophthalmologist who in 1842 coined the word hypnosis after the
word for sleep.
Braid reportedly put people into trances by staring at them intently,
did not have a clue as to how it worked. In this vacuum, hypnosis was
adopted by spiritualists and stage magicians who used dangling gold
to induce hypnotic states in volunteers from the audience, and make
dance, sing or pretend to be someone else, only to awaken at a hand
laughter from the crowd.
In medical hands, hypnosis was no laughing matter. In the 19th century,
physicians in India successfully used hypnosis as anesthesia, even for
amputations. The practice fell from favor only when ether was
Now, Dr. Posner and others said, new research on hypnosis and
providing a new view into the cogs and wheels of normal brain function.
One area that it may have illuminated is the processing of sensory
Information from the eyes, ears and body is carried to primary sensory
regions in the brain. From there, it is carried to so-called higher
where interpretation occurs.
For example, photons bouncing off a flower first reach the eye, where
are turned into a pattern that is sent to the primary visual cortex.
the rough shape of the flower is recognized. The pattern is next sent
higher - in terms of function - region, where color is recognized, and
to a higher region, where the flower's identity is encoded along with
knowledge about the particular bloom.
The same processing stream, from lower to higher regions, exists for
touch and other sensory information. Researchers call this direction of
feedforward. As raw sensory data is carried to a part of the brain that
creates a comprehensible, conscious impression, the data is moving from
bottom to top.
Bundles of nerve cells dedicated to each sense carry sensory
The surprise is the amount of traffic the other way, from top to
called feedback. There are 10 times as many nerve fibers carrying
information down as there are carrying it up.
These extensive feedback circuits mean that consciousness, what people
hear, feel and believe, is based on what neuroscientists call "top down
processing." What you see is not always what you get, because what you
depends on a framework built by experience that stands ready to
the raw information - as a flower or a hammer or a face.
The top-down structure explains a lot. If the construction of reality
much top-down processing, that would make sense of the powers of
sugar pill will make you feel better), nocebos (a witch doctor will
ill), talk therapy and meditation. If the top is convinced, the bottom
of data will be overruled.
This brain structure would also explain hypnosis, which is all about
creating such formidable top-down processing that suggestions overcome
According to decades of research, 10 to 15 percent of adults are highly
hypnotizable, said Dr. David Spiegel, a psychiatrist at Stanford who
the clinical uses of hypnosis. Up to age 12, however, before top-down
circuits mature, 80 to 85 percent of children are highly hypnotizable.
One adult in five is flat out resistant to hypnosis, Dr. Spiegel said.
rest are in between, he said.
In some of the most recent work, Dr. Amir Raz, an assistant professor
clinical neuroscience at Columbia, chose to study highly hypnotizable
with the help of a standard psychological test that probes conflict in
brain. As a professional magician who became a scientist to understand
better the slippery nature of attention, Dr. Raz said that he "wanted
something really impressive" that other neuroscientists could not
The probe, called the Stroop test, presents words in block letters in
colors red, blue, green and yellow. The subject has to press a button
identifying the color of the letters. The difficulty is that sometimes
word RED is colored green. Or the word YELLOW is colored blue.
For people who are literate, reading is so deeply ingrained that it
invariably takes them a little bit longer to override the automatic
of a word like RED and press a button that says green. This is called
Sixteen people, half highly hypnotizable and half resistant, went into
Raz's lab after having been covertly tested for hypnotizability. The
of the study, they were told, was to investigate the effects of
on cognitive performance. After each person underwent a hypnotic
Dr. Raz said:
"Very soon you will be playing a computer game inside a brain scanner.
time you hear my voice over the intercom, you will immediately realize
meaningless symbols are going to appear in the middle of the screen.
will feel like characters in a foreign language that you do not know,
you will not attempt to attribute any meaning to them.
"This gibberish will be printed in one of four ink colors: red, blue,
or yellow. Although you will only attend to color, you will see all the
scrambled signs crisply. Your job is to quickly and accurately depress
key that corresponds to the color shown. You can play this game
effortlessly. As soon as the scanning noise stops, you will relax back
your regular reading self."
Dr. Raz then ended the hypnosis session, leaving each person with what
called a posthypnotic suggestion, an instruction to carry out an action
while not hypnotized.
Days later, the subjects entered the brain scanner.
In highly hypnotizables, when Dr. Raz's instructions came over the
the Stroop effect was obliterated, he said. The subjects saw English
as gibberish and named colors instantly. But for those who were
hypnosis, the Stroop effect prevailed, rendering them significantly
in naming the colors.
When the brain scans of the two groups were compared, a distinct
appeared. Among the hypnotizables, Dr. Raz said, the visual area of the
brain that usually decodes written words did not become active. And a
in the front of the brain that usually detects conflict was similarly
Top-down processes overrode brain circuits devoted to reading and
conflict, Dr. Raz said, although he did not know exactly how that
Those results appeared in July in The Proceedings of the National
A number of other recent studies of brain imaging point to similar
brain mechanisms under the influence of suggestion. Highly hypnotizable
people were able to "drain" color from a colorful abstract drawing or
color to the same drawing rendered in gray tones. In each case, the
their brains involved in color perception were differently activated.
Brain scans show that the control mechanisms for deciding what to do in
face of conflict become uncoupled when people are hypnotized. Top-down
processes override sensory, or bottom-up information, said Dr. Stephen
Kosslyn, a neuroscientist at Harvard. People think that sights, sounds
touch from the outside world constitute reality. But the brain
what it perceives based on past experience, Dr. Kosslyn said.
Most of the time bottom-up information matches top-down expectation,
Spiegel said. But hypnosis is interesting because it creates a
imagine something different, so it is different," he said.