What Hypnosis Does to the Brain

Hypnosis May Lower Activity in Certain Brain Areas, Say Researchers

June 27, 2005 -- How does hypnosis work? It may lull brain areas into going along with suggestions made during hypnosis.

That theory was tested in a new hypnosis study. In the project, researchers used brain scans to watch the brain under the influence of hypnosis.

The experiment was done at Cornell University's medical school. The findings appear in Proceedings of the National Academy of Sciences.

Hypnosis Study

Participants were 16 healthy young adults. Some were more influenced by hypnosis than others.

They had a seemingly simple task. Their job: Identify the color of a word on a computer screen.

The catch: The words were names of colors typed in a mismatched color. For instance, the word "green" might have appeared in red.

It's a classic brain-teaser used in mental studies.

Under hypnosis, subjects were told that their chore would be a breeze. They would have no problem reading the color names correctly, they were told.

That proved true for those who took to hypnosis best. Those who weren't as suggestible took about 10% longer to name the colors.

Why the Brain Believed It

Specialized MRI brain scans showed less activity in two areas of the hypnotized brain.

The first area is involved in visual processing. The other may be important in handling conflicts, say the researchers.

That could mean that the brains of highly hypnotizable people were more accepting of the instructions, say Michael Posner, PhD, and colleagues.

Posner worked on the study. He is a professor emeritus of psychology at the University of Oregon and an adjunct professor at Cornell University's Weill Medical College.

The researchers say that these results could also help explain the power of suggestion under other circumstances. For instance, what effect does the placebo effect -- where people get benefit from a medical treatment (for example, a sugar pill) purely because they think it's going to help - have on the brain?

Show Sources

SOURCES: Raz, A. Proceedings of the National Academy of Sciences, early edition. News release, Proceedings of the National Academy of Sciences.

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