快猫短视频

The year is 1970. The venue: a television studio in the north of England. The
鈥渁mazing Kreskin鈥�, alias George Kresge, renowned American stage magician, begins
his act and among those who volunteer to fall under his spell is a 22-year-old
student.

First there is the familiar patter (鈥渃oncentrate-on-my-voice鈥�,
鈥測our-eyelids-are-feeling-heavy鈥� . . .). Then come the commands to do daft
things. Soon the student is falling over backwards, behaving as though his hands
are stuck together, and, by way of a finale, insisting his bottom is glued to a
chair. The volunteer looks strangely detached throughout. He looks for all the
world like someone in the throes of a trance.

Except that was no trance. Or so, at least, says Graham Wagstaff. And as a
reliable witness, this psychologist from the University of Liverpool has two
things going for him: (a) He was that student; (b) He went on to become a
leading hypnosis researcher.

For more than two decades Wagstaff has been promulgating the view that
hypnosis involves nothing more than everyday levels of suggestibility and
imagination spiced up with some kow-towing to authority and, on occasion, not a
little pretence. In the clinic, as on stage, strange things do happen. A few
words from a hypnotist and subjects may say they are colour blind or cannot move
their arms, or that they have regressed to the age of five. Solid objects may
become invisible, large numbers written in clear black ink unreadable. And
subjects can be induced to forget almost anything, even their own names. But all
these behaviours can be explained by role playing or pretence, says Wagstaff. No
need to invoke exotic things like trances.

But by no means everyone who studies hypnosis thinks this way. Not by a long
chalk.

The so-called 鈥渟tate theorists鈥� are the true believers. They argue that
hypnosis can induce a special state of focused concentration鈥攁 trance in
which people can use their brains in unusual ways, hallucinating at will and
becoming aloof from sensations like pain. And, no, we are not talking about
cranks here, but tenured professors and their research students who, in journals
and at conferences, have been slugging it out with the sceptics for years.

People like David Spiegel, Stanford neuropsychologist and doctor. The idea
that hypnosis is nothing more than play acting and everyday suggestibility fills
Spiegel with despair. 鈥淚 wouldn鈥檛 mind,鈥� he says. 鈥淏ut you get your grants
reviewed and somebody says, `well, there are all these articles that say
hypnosis is nothing but social compliance, so why should we fund a study on
hypnosis?鈥� 鈥�

Some studies do get funded, however, and state theorists hope their latest
experiments will shift opinion their way. Forget pocket watches swinging from
side to side in darkened rooms. These days, experiments involve subjects
following the commands of a hypnotist while lying in a brain scanner, or sitting
beneath a nest of scalp electrodes as they spew out data to a computer.

Some of the latest experiments have been taking place in Boston, where
Spiegel and his colleagues have teamed up with a group of Harvard imaging
experts, including Stephen Kosslyn and William Thompson. In Massachusetts
General Hospital, the researchers have been using positron emission tomography
(PET scanning) to measure blood flow changes linked to hypnosis. 鈥淲e鈥檙e excited
about the effects we鈥檙e seeing,鈥� says Thompson, 鈥渂ut we don鈥檛 know for sure what
they mean until we鈥檝e analysed all the data.鈥�

In one experiment, after a hypnotist had attempted to put them in a trance,
the subjects were told to manipulate in their mind鈥檚 eye pieces of artwork shown
to them on a computer screen inside the scanner. They either had to 鈥渃olour in鈥�
grey images or become 鈥渃olour blind鈥�, seeing only in shades of grey when faced
with images containing real colours. Both are hallucinations that hypnotised
people are supposed to be able to achieve at will.

Some subjects were unable to experience the colour hallucinations. But others
reported more success. This is what you鈥檇 expect, because if there鈥檚 one thing
hypnosis researchers agree on it鈥檚 that not everyone is hypnotisable, and of
those who are, only a few, maybe one in five, are highly susceptible. Where
researchers clash is over whether these virtuoso subjects fake it or experience
genuinely altered perception.

Although the Harvard team is still analysing its results, Spiegel says the
early signs are that their findings support the idea that the hallucinations are
real. The brain scans of hypnotised subjects who claimed success with the colour
manipulations were different from those of subjects who tried and failed. What鈥檚
more, some of the differences were in specific and highly relevant parts of the
brain.

Spotting the fakers

Among people who claimed they had become 鈥渃olour blind鈥�, for example, there
was a change in blood flow to an area of the cortex believed to be the brain鈥檚
main colour centre
(see Diagram). A faker couldn鈥檛 produce such distinctive
brain changes, Spiegel says. 鈥淲hen these people tell you subjectively that
they鈥檙e seeing colour when they鈥檙e not or they鈥檙e not seeing colour when they
are, their brain looks as though it鈥檚 experiencing the perception
诲颈蹿蹿别谤别苍迟濒测.鈥�

A similar story is unfolding at the University of Montreal in Canada. Pierre
Rainville, Catherine Bushnell and their colleagues have also been investigating
hypnosis with PET, this time in connection with pain control. In a study
published last year in Science, (vol 277, p 968) the Montreal team
hypnotised eight volunteers鈥攁ll chosen because of their susceptibility to
hypnosis鈥攁sking each to place a hand in a tub of painfully hot water. In
the suggestive patter that followed, subjects were told that the hot water was
either more or less unpleasant than it really was.FIG-mg21415501.JPG

On cue, everyone responded by accepting that their perception really had
changed. Were they pretending? Not according to the brain scans, say the
researchers. The suggestive patter induced big changes in the brain鈥檚 anterior
cingulate, part of a structure that lines the inner surface of the cortex. Blood
flow increased when the hypnotist suggested that the pain was more unpleasant,
and fell in response to suggestions that it was less unpleasant.

Why might that mean the subjects weren鈥檛 faking? Well, the details are
sketchy, but one of the anterior cingulate鈥檚 jobs seems to involve setting the
volume and tone of the emotional 鈥渟oundtrack鈥� that the brain attaches to
perceptions and thoughts. If hypnosis really was helping subjects to take the
emotional sting out of the pain they felt, this would be one brain area where
you would predict changes. But, for the researchers, what clinched it was that
the blood flow changes correlated so well with what people claimed to be
feeling: the more the pain seemed to hurt, the more this region of the brain lit
up in the scans, and vice versa.

Brain imaging is not the only technique you can use to probe the honesty of
hypnosis subjects. It鈥檚 well known that people who are unresponsive to hypnosis
can mimic the effects of being hypnotised, often fooling the hypnotist that they
are under her or his spell.

But some years ago, Irving Kirsch at the University of Connecticut in Storrs
and his colleagues designed experiments that detected important differences
between 鈥渟imulators鈥� and 鈥渞eals鈥�. They asked their subjects to listen to a tape
of a hypnotist twice: first with no researchers present (subjects were told this
was a practice session), and then with an experimenter standing in the room.
What none of the subjects knew was that both times they were being secretly
filmed.

Simulators were twice as responsive to suggestions (such as 鈥測our arms are
floating鈥� or 鈥測our fingers are locked鈥�) when they knew they were being observed
than when they were led to believe they were alone. But the reals responded well
both times, even when they thought no one was watching them. Why would they do
that, asks Kirsch, if their behaviour was nothing but a show to please the
hypnotist?

Still, accepting that at least some hypnosis subjects aren鈥檛 faking is not
the same as believing in trance states. Must 鈥渞eal鈥� hypnotic experiences go hand
in hand with subjects entering a special state? Once again, opinions are
divided. Kirsch and others say no, the state theorists yes. The problem they
have is deciding what this trance state might consist of.

It鈥檚 not sleep, they say, and it鈥檚 not quite dreaming, either. When forced to
speculate, most draw instead on the idea that in hypnosis, the brain 鈥渢urns in
on itself鈥�, losing track of time and interest in the external world, and gaining
the ability to treat products of the imagination as real and believable.
鈥淪ensations from the external world no longer dominate consciousness which can
now be modified more readily by suggestions,鈥� suggests Rainville. 鈥淏ut maybe
that鈥檚 pushing it a little.鈥�

At the Imperial College School of Medicine in London, neuropsychologist John
Gruzelier and his colleagues have been bringing scalp electrodes and subtle
psychological tests to bear on the problem. Gruzelier鈥檚 results seem to confirm
the importance of mental focusing. In the early stages of the patter or
induction routine, you have to be able to shut out distractions and focus on the
hypnotist鈥檚 voice to the exclusion of almost everything else. People who are
easily hypnotised can quickly train their brains to ignore sounds, for
example.

But according to Gruzelier, this isn鈥檛 enough. You also have to be able to
鈥渓et go鈥�. When a hypnotist talks about tiredness and heavy eyelids, susceptible
subjects respond by relaxing some of the brain circuits in the frontal lobes
that usually monitor and plan our thoughts and behaviours, suggests Gruzelier.
The result is more than simple inattentiveness.

In one set of tests, his team hypnotised subjects who then had to click
buttons in response to visual cues, quickly changing their responses as the
colour of the cue changed. Subjects who were susceptible to hypnosis made more
errors than people who weren鈥檛. Yet the team鈥檚 scalp recordings showed that the
hypnotised subjects鈥� brains were just as good at detecting the errors鈥攖hey
just weren鈥檛 using the information to improve their reactions.

In hypnosis, says Gruzelier, 鈥測ou don鈥檛 really process the consequences of
making an error鈥�. You lose interest in testing and criticising your own
perceptions and behaviours, and, as a result, become credulous to suggestions
and the products of the imagination.

Altered state

Gruzelier鈥檚 studies also show that hypnosis impairs verbal fluency and skills
linked to the left frontal lobe. And for him, this is no accident. Slowing down
the left frontal lobe, famous for logic and verbal reasoning, might be one way
to suspend the brain鈥檚 critical faculties.

And, in Montreal, Rainville and his colleagues have taken a different
approach to try and show that hypnosis changes the way the brain works. They
have been using PET to investigate what happens to the brain during the
hypnotist鈥檚 induction routine. In a paper to be published later this year, the
researchers claim to see a series of activity changes which together add up to
the brain signature of an 鈥渁ltered state鈥�, at least in people who are
susceptible to hypnosis.

Wagstaff sighs. None of these arguments comes close to impressing him. The
patterns seen in the brain scans are correlates not of trance states, he says,
but of perfectly ordinary mental and physical changes such as increased
concentration and relaxation. 鈥淭hey鈥檙e physiological expressions of whatever
instructions are given to the subjects.鈥�

In Wagstaff鈥檚 view, many researchers are coming unstuck because they think of
hypnosis as a single, definable thing, when it鈥檚 actually everything and
anything a hypnotist wants it to be. If you tell people to imagine colours or to
distract themselves from the unpleasantness of a pain sensation, don鈥檛 be too
surprised if that鈥檚 what some of them鈥攖he ones skilled in imaginative role
playing鈥攄o, says Wagstaff. And don鈥檛 be too surprised, either, to see
changes in brain areas dealing with vision and pain.

And if subjects insist that the vase in front them really is invisible or
that, no, they really can鈥檛 remember their own name? Well, they鈥檙e pretending.
Wagstaff points out that if you rig subjects up to a lie detector and then
screen a video recording of them performing under hypnosis, most will admit they
were role playing rather than experiencing real hypnotic amnesia. He doesn鈥檛 say
that all subjects are faking, or that hypnosis therapies are bogus, just that
there is a line to be drawn. People using their imaginations to distract
themselves from pain, yes; people claiming to have 鈥渞eal鈥� altered experiences
courtesy of a trance, no.

Others doubt such a line can be drawn. At first glance it might seem odd for
people to say they are experiencing things that they know don鈥檛 exist, but such
鈥渃ounterfactual鈥� sensations are by no means unique to hypnosis. The vividness of
dreams alone shows that the brain has what it takes to concoct them. And as any
number of visual illusions reveal, even when we are wide awake, what we 鈥渟ee鈥� is
not a simple reflection of the physical world, but a complex simulation of it,
the product of expectations and neural processing as much as photons striking
the retina.

鈥淎ll perception is a combination of some raw sensory input and some internal
mental image or context,鈥� says Spiegel. 鈥淚n hypnosis we鈥檙e setting up a
competition between the two . . . we鈥檙e saying use the internal image to change
what you see.鈥�

But can the brain do this on command? Dreams and illusions, after all, tend
to be beyond our control.

No doubt about it, says Kirsch: especially if the subject expects hypnosis to
work. Years ago, Kirsch and a colleague found they could improve people鈥檚
response to hypnosis simply by exposing them to a few faked hypnotic
experiences. They would sit the subjects in a dimly lit room, hypnotise them,
then suggest that they were about to imagine colours on the wall or hear some
imaginary music. Then, unbeknown to the subjects, they would turn on hidden
lights and a tape machine. The changes were for real, yet subjects believed they
were the products of their imaginations and hypnosis. For many, it was enough to
change their expectations about hypnosis and boost their scores in standard
tests of hypnotisability.

But if Kirsch is kinder than Wagstaff about faking in hypnosis, he is just as
sceptical about trance states. The brain-imaging studies simply support the idea
that suggestions can radically alter our behaviour and experience, Kirsch says.
What they don鈥檛 show is that hypnosis is necessary for suggestions to have such
effects. Do the brains of hypnotisable people respond any differently to
suggestions after they have been hypnotised compared with before? Nobody has
shown they do, says Kirsch, and that鈥檚 probably because hypnosis doesn鈥檛 produce
any differences.

Stories about hypnosis enabling people to face abdominal surgery without
anaesthesia, or shed warts, or overcome psoriasis sound remarkable. But bear in
mind, say the sceptics, that sham injections and other placebos can achieve
similar effects (see 鈥淎 weight off your mind鈥�, below). Indeed, according to
Kirsch, even the most basic aspect of hypnosis鈥攖hat it makes people more
suggestible鈥攊s open to debate. What hypnosis is really good for, he says,
is not boosting suggestibility but shining a torch on it. In other words,
hypnosis merely singles out people who are already suggestible.

Last year Kirsch developed this theme in a provocative paper calling on
fellow researchers to abandon or redefine the terms hypnosis and
hypnotisability, and to reflect on what is really being measured in hypnosis
experiments: suggestibility. Until that happens, he wrote, 鈥渨e will continue to
delude ourselves about the meaning of our data鈥�. History, he added, 鈥渉as a way
of catching up with sophistry鈥攁nd the verdict of history is generally less
than kind鈥�.

But is the emperor really so nude? Back in the state theorist camp, nobody
thinks so. To say that hypnosis has its influence solely through 鈥渞ole-playing
or other psychosocial dynamics is naive,鈥� argues Gruzelier. Nor are state
theorists about to desert their prize hypothesis on the grounds that some
hypnotisable people respond just as well to suggestions when they haven鈥檛 been
formally hynotised. Perhaps suggestions alone are enough to induce the trance
state in these people.

In other words, both sides are claiming victory, and perhaps that is not so
surprising. After all, people have been entangled in arguments about the
nature of hypnosis ever since the word was invented in the 1840s. And although
imaging techniques and scalp recordings seem, outwardly, powerful enough to cut
the knot, appearances can be deceiving: what they measure is blood flow and
electrical activity, not what people are thinking. To expect a consensus about
the nature of hypnosis to emerge when nobody even knows how the brain produces
everyday consciousness is rather optimistic.

That, at any rate, must be what the amazing Kreskin is banking on. So
convinced is this stage hypnotist that trances don鈥檛 exist that he is offering
$100 000 to anyone who can prove him wrong. So step forward, would-be
challengers. Just remember that Kreskin has already been to court twice to fight
off claims. Both times, he won.

YOU don鈥檛 need to believe in trances to believe hypnosis can do good. Even
hard-nosed sceptics think it can offer relief from conditions such as chronic
pain and insomnia.

But how much? And for that matter, how?

Irving Kirsch of the University of Connecticut has pooled results from 18
trials that looked at the ability of hypnosis to enhance behaviour-altering
therapies such as relaxation coaching, counselling and training in coping
strategies. The trials covered conditions ranging from chronic pain, insomnia
and intense anxieties to high blood pressure and obesity.

According to Kirsch鈥檚 analysis, hypnosis tends to improve the effectiveness
of such therapies鈥攂ut not miraculously so. On average, patients who
received therapy and hypnosis fared better than two-thirds of the patients who
received just therapy.

The benefits of hypnosis peaked in patients trying to lose weight, leading to
twice as much weight being shed. Still, hypnosis didn鈥檛 create any Kate Mosses.
An average weight loss of 6 kilograms meant patients were still obese.

Some researchers speculate that the health benefits of hypnosis are due to a
placebo effect. Just as one person may respond to a sugar pill, they say,
another may find hypnosis helpful.

But many researchers who think hypnosis depends on specific changes in brain
function recoil at this suggestion. They point out that in experiments testing
tolerance to the pain experienced by subjects when they grasp an ice cube,
hypnosis works better than sham pills, at least in those who are easily
hypnotised. Ergo hypnosis and placebos are different.

Critics counter that all this really shows is that hypnosis is the most
effective type of placebo to give people who are easily hypnotised.

Kirsch鈥檚 view is different again. Placebos convince subjects that the world
really is different than it is鈥攖hat the little green sugar pill dissolving
in their mouth really is a medicine. Hypnosis, says Kirsch, involves a subtler,
more complex suggestibility. People are asked to imagine that the pain isn鈥檛 so
bad. And then they鈥檙e told to experience the world and their own minds as if
this state of affairs were true. Kirsch calls this 鈥渋maginative suggestibility鈥�.