Sex differences and incentive effects on perceptual and cardiovascular responses to cold pressor pain.

OBJECTIVE: Sex differences in pain perception have been widely reported, with women typically displaying greater pain sensitivity than men, but the mechanisms underlying these differences remain unclear. One possible explanation suggests that men are more motivated to tolerate and suppress expressions of pain because of the masculine sex role, whereas the feminine sex role encourages pain expression and produces lower motivation to tolerate pain among women.
METHODS: To examine the influence of motivation on perceptual and cardiovascular responses to pain among women and men, different levels of monetary incentive (high vs. low incentive) were provided to a group of 81 healthy young adults undergoing the cold pressor pain procedure. It was anticipated that men would have greater endogenous motivation and would therefore be less affected by the external incentive.
RESULTS: Men had higher pain thresholds and tolerances and lower pain ratings than women, but the incentive condition produced no significant effect on pain responses. Resting blood pressure was positively correlated with pain tolerance among the low incentive group, whereas blood pressure reactivity to the cold pressor predicted pain tolerance in the high incentive group.
CONCLUSIONS: Thus, monetary incentive did not influence pain responses, but the relationship between cardiovascular measures and pain responses was influenced by the incentive manipulation. Potential explanations for the observed results are presented, and the implications for applying the biopsychosocial model to pain research are discussed.