Genuine, suppressed and faked facial behavior during exacerbation of chronic low back pain.

Facial activity was examined as 60 female and 60 male chronic low back pain patients responded to a painful range of motion exercise during a scheduled physical examination. Subsequently, they were asked to fake the facial response to the movement inducing the most pain or to attempt to suppress evidence that they were experiencing pain when this same movement was again repeated. Facial behavior was measured using the Facial Action Coding System. Self-reports of pain also were provided. The genuine expression was consistent with that observed in previous research, but minor differences indicated that the facial display of pain reflects differences between sources of pain, social context in which pain is induced and individual differences among patients. Considerable voluntary control over the facial expression of pain was observed, although the faked expression was more an intensified caricature of the genuine expression, and an attempt to suppress the facial grimace of pain was not entirely successful as residual facial activity persisted. Self-reports were only moderately correlated with facial behavior.