SEX-DIFFERENCES IN RESPONSIVENESS TO PAINFUL AND NONPAINFUL STIMULI ARE DEPENDENT UPON THE STIMULATION METHOD

Sex differences in thermo- and electrocutaneous responsiveness to pain ful and non-painful stimuli were investigated in 20 women and 20 men. Heat pain, warmth, and cold thresholds were assessed on the hand and f oot with a Peltier thermode system. In addition, subjects used magnitu de estimation to judge the sensation intensity evoked by temperatures ranging from 38-degrees-C to 48-degrees-C applied to the forearm. To m easure detection, pain, and tolerance thresholds of electrocutaneous s ensitivity, electrical pulses were administered to the hand. Magnitude estimates of sensation intensity were assessed for stimuli ranging fr om 0.5 mA to 4.0 mA. There were no sex differences in heat pain, warmt h and cold thresholds. There were significant sex differences in elect rical detection, pain and tolerance thresholds, with lower thresholds in women. Correspondingly, magnitude estimates were similar in women a nd men when using thermal stimuli while women judged stimuli from 2.5 mA on as more intense than men when using electrical stimuli. Despite these discrepancies, the measures for pain responsiveness from the two stimulation methods correlated significantly. In contrast, no signifi cant correlations between the methods were found when considering the responsiveness to non-painful stimuli. The findings help to clarify co ntroversies in the pain literature about sex differences. Results affi rming and denying such differences could be obtained within a single s ample, with stimulation method as the critical variable.