Anatomy of a hypnotic response: Self-report estimates, actual behavior, and physiological response to the hypnotic suggestion for arm rigidity.

The present study closely examines subject response to the arm-rigidity item of the HGSHS:A. Subject behavior, subject self-report, and surface EMG of the biceps and triceps muscles were monitored. Two distinct ways of passing the item were observed and verified by EMG recordings: some subjects (tremblers) exerted muscular effort to bend the arm and kept it rigidly straight. Others (nontremblers) passively kept the arm straight without exerting muscular effort to bend, even though they reported exerting effort to bend their arm. These two behaviorally and physiologically different methods of passing the item support the idea of individual differences in hypnotic responding and suggest that subjects may be using different mental processes to pass the item.