Neuropsychological evidence of reductions on left frontal tests with hypnosis

Individuals with high and low susceptibility to hypnosis were compared in a baseline condition and after instructions of hypnosis on tests of anterior left and right hemispheric functions--word fluency to letter categories, word fluency to semantic categories, design fluency and bilateral finger tapping dexterity. With hypnosis high susceptibles showed a reduction in word generation to letter categories, no significant change in word generation to semantic categories, an improvement in design fluency, and bilateral reductions in finger tapping dexterity. Low susceptibles showed the opposite changes except for the improvement in design fluency. These results, together with correlational results, were interpreted as evidence of central inhibitory processes, particularly of the left hemisphere, in response to instructions of hypnosis in high susceptibles.