Effects of being observed on expressive, subjective, and physiological responses to painful stimuli.

Two experiments explored the effects of observation by another on responses to painful stimuli. It was anticipated that the intensity of pain-related non-verbal expressivity decreases under observation, while indices of arousal (skin conductance and self-report) increase. In Experiment 1, subjects' expressive responses to shock were attenuated when subjects were observed as compared to when they were alone, but the anticipated augmentation of arousal did not occur. Rather, the attenuation of expressive behavior was accompanied by a general decrease in subjective and autonomic responses to the painful stimuli. A second experiment replicated the results of the first study and, in addition, found no evidence for a differential impact of sex of observer on the three measures of arousal. An interpretation is discussed for the effect of observation on expressive behavior and for the relationships observed among expressive, autonomic, and subjective indices of pain.