Hypnosis, with its long and checkered history in medicine and entertainment, is receiving some new respect from neuroscientists. Recent brain studies of people who are susceptible to suggestion indicate that when they act on the 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 were hypnotized "saw" colors where there were none. Others lost the ability to 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 Posner, an emeritus 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 in medicine since the 1950s to treat pain and, more recently, as a treatment for anxiety, depression, trauma, irritable bowel syndrome and eating disorders.
There is, however, still disagreement about what exactly the hypnotic state is or, indeed, whether it is anything more than an effort to please the hypnotist or a natural form of extreme concentration where people become oblivious to their surroundings while lost in thought.
Hypnosis had a false start in the 18th century when a German physician, Dr. Franz Mesmer, devised a miraculous cure for people suffering from all manner of unexplained medical problems. Amid dim lights and ethereal music played on a glass harmonica, he infused them with an invisible "magnetic fluid" that only he was able to muster. Thus mesmerized, clients were cured.
Although Mesmer was eventually discredited, he was the first person to show that the mind could be manipulated by
suggestion to affect the body, historians say. This central finding was resurrected by Dr. James Braid, an English ophthalmologist who in 1842 coined the word hypnosis after the Greek word for sleep.
Braid reportedly put people into trances by staring at them intently, but he 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 watches to induce hypnotic states in volunteers from the audience, and make them dance, sing or pretend to be someone else, only to awaken at a hand clap and 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 limb amputations. The practice fell from favor only when ether was discovered.
Now, Posner and others said, new research on hypnosis and suggestion is 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 data. 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 regions where interpretation occurs.
For example, photons bouncing off a flower first reach the eye, where they are turned into a pattern that is sent to the primary visual cortex. There, the rough shape of the flower is recognized. The pattern is next sent to a higher -- in terms of function -- region, where color is recognized, and then to a higher region, where the flower's identity is encoded along with other knowledge about the particular bloom.
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