Facial expression during induced pain.

Facial expressions contribute substantially to judgments of sufferer's pain but have not been rigorously described. We obtained a detailed description of 72 female volunteers' facial reactions to the cold pressor experience, using Ekman and Friesen's (1978a) objective, anatomically based Facial Action Coding System. In addition, we examined the impact of exposure to social models tolerant or intolerant to pain. The facial actions systematically provoked by cold pressor exposure comprised a narrowing of the eye aperture from below, raising the upper lip, pulling the lip corners, parting of the lips, or dropping the jaw, and eyes closing or frequently blinking; however, there was rich individual variation in the facial displays. The reactions were most salient at onset, indicating blends of startle, adaptive reaction, emotional expression, and pain, but they declined in vigor over time, although self-report of pain continued to mount. The relation between subjective distress and facial expression was greatest at the beginning of noxious stimulation. The social models had a potent impact on verbal report and pain tolerance but not on facial expression, indicating relative independence of components within the rich range of expressive reactions of painful experience.