Bruce Ledford, Elizabeth Brazelton and David Shannon found that women were more susceptible to hypnotic suggestion than men in a study of 280 student volunteers. The study sought to identify the relationships among traits that identify people as susceptible to subliminal suggestion through such methods as hypnosis. Certain college majors were found to be more susceptible than others, but the study traced the link back to the student's gender. The difference, however, was not significant when gender was factored out. Hypnosis is used in some psychological studies and therapies, but only about 15 percent of the population is highly susceptible to hypnotism, and another 10 percent to 15 percent is almost completely unresponsive.
Most people fall between the tw o extremes, the study notes.
Test subjects were asked to perform simple tasks such as moving their arms or keeping their eyes open after being told under hypnosis that they would not be able to do so. Subjects who were hypnotized heeded the hypnotic suggestion. They also did n ot flinch when smelling ammonia. The researchers compared a hypnosis scale for hypnotic susceptibility developed at Harvard University with one developed at Stanford University and found them to be equally effective. The Educational Foundations, Leadership and Technology faculty member said he is trying to find factors that account for the success of subliminal messages with some people but not others.