Manipulation of perception
Around 12 – 15 % of the U.S adult population is highly hypnotizable , study showed that 80-85 % of children are also highly hypnotizable. A recent study on highly hypnotizable people showed that their perception can be manipulated under hypnosis in fact, according to Dr. Stephen M. Kosslyn, a neuroscientist at Harvard. People think that sights, sounds and touch from the outside world constitute reality. But the brain constructs what it perceives based on past experience, Kosslyn said.
To quote the study conducted by Dr. Amir Raz:
The probe, called the Stroop test, presents words in block letters in the colors red, blue, green and yellow. The subject has to press a button identifying the color of the letters. The difficulty is that sometimes the word RED is colored green. Or the word YELLOW is colored blue.
For people who are literate, reading is so deeply engrained that it invariably takes them a little bit longer to override the automatic reading of a word like RED and press a button that says green. This is called the Stroop effect.
Sixteen people, half highly hypnotizable and half resistant, went into Raz’s lab after having been covertly tested for hypnotizability. The purpose of the study, they were told, was to investigate the effects of suggestion on cognitive performance. After each person underwent a hypnotic induction, Raz said:
“Very soon you will be playing a computer game inside a brain scanner. Every time you hear my voice over the intercom, you will immediately realize that meaningless symbols are going to appear in the middle of the screen. They will feel like characters in a foreign language that you do not know, and you will not attempt to attribute any meaning to them.
“This gibberish will be printed in one of four ink colors: red, blue, green 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 the key that corresponds to the color shown. You can play this game effortlessly. As soon as the scanning noise stops, you will relax back to your regular reading self.”
Raz then ended the hypnosis session, leaving each person with what is 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 Raz’s instructions came over intercom, the Stroop effect was obliterated, he said. The subjects saw English words as gibberish and named colors instantly. But for those who were resistant to hypnosis, the Stroop effect prevailed, rendering them significantly slower in naming the colors.
When the brain scans of the two groups were compared, a distinct pattern appeared. Among the hypnotizables, Raz said, the visual area of the brain that usually decodes written words did not become active. And a region in the front of the brain that usually detects conflict was similarly dampened.
