FRIDAY, Aug. 31, 2001 (HealthDayNews) -- Hypnosis is not all it's cracked up to be when you're seeking the truth, warns an Ohio State psychologist.
In a study of college students, half of whom were hypnotized, Joseph Green found that the hypnotized students were 1½ times more confident of their answers to a current events test than were the students who weren't hypnotized.
Unfortunately, Green says their confidence was misplaced, as they were no more accurate in their answers than the non-hypnotized group.
"There is a widespread belief that hypnosis produces accurate memories. The public isn't well-informed about that," Green says.
Further, his study found that the misplaced confidence is largely unconscious and that the hypnotized students' actions, rather than what they said, showed their increased confidence.
Green presented his findings at the this week's annual meeting of the American Psychological Association in San Francisco.
In the study of 96 students, 51 were hypnotized and 45 performed relaxation techniques and then were asked to estimate the dates of various historical events, like the beginning of the Gulf War, when the bomb exploded in Atlanta during the Olympics and the date of rock star's Kurt Cobain's suicide.
After taking the test, the participants were asked to rate how confident they were of their answers, and both groups reported a low level of confidence, three out of a possible seven.
All the participants then were told they could change any answers they wanted to, and this was where the two groups differed. The students who had been hypnotized changed only 16.9 percent of their answers, compared with the non-hypnotized students, who changed 24.6 percent of their answers.
Green says, "Both groups have equal confidence in their responses on a conscious level, but their behaviors were different. The lack of willingness [by the hypnotized students] to change answers when asked to do so indicates that at some level they had greater trust in their answers."
Green says the implications of his finding is that hypnosis does not work well as a memory-recovery technique, and that people's misplaced confidence in its accuracy could lead to problems.
"There are many people who think that hypnosis should not be used as a memory-recovery technique, and there's reason to adopt that opinion. Hypnosis, because it's so suggestive, often results in memory contamination effects. That and increased confidence are ingredients for false memories that persist," he says.
However, Green says hypnosis has a place in treating moderate psychopathy.
"While hypnosis is not the recommended tool for memory retrieval, it should not be discarded as a legitimate clinical tool" to help people lose weight or stop smoking, he says.
Emory University psychology professor Stephan Hamann says, "It's not a new finding about hypnosis -- that you can have people come up with information that's not true and have a false sense of confidence about it -- but it sounds like the conscious-versus-unconscious aspect [of the study] is probably the most novel."