Fig. 4.

The first pain rating given for each thermal stimulus series (47°C and 48°C) significantly increased with temperature for each group in the study. This indicates that all groups were capable of discerning temperature differences between the 2 sets of heat stimuli. When comparing the groups within each temperature series, there were no differences in the first pain ratings reported. The Y axis depicts group means for first pain ratings on a scale of 0 (no pain) to 100 (worst possible pain). Error bars represent standard error of the mean. Asterisks indicate significant differences between groups at the level of P < .05.