Subjective intensity ratings of the sensation elicited by the IES of responders (left) and nonresponders (right). A: to highlight the interaction between the factors Session and Hand, the subtracted ratings (post- minus pre-capsaicin injection) are shown for each hand. Colored circles indicate single subjects, and black circles indicate the group average for each condition. Two-way ANOVA revealed that responders had a highly significant interaction between the factors Session and Hand. This reveals a capsaicin-induced increase of IES ratings (Post − Pre) on the right hand. In contrast, in nonresponders the 2-way ANOVA revealed a decrease of IES ratings on the right hand compared with those on the left hand. These differences in the capsaicin effect on IES ratings between responders and nonresponders were confirmed by the 3-way ANOVA, which revealed a highly significant triple interaction (Group × Session × Hand; comparison between left and right panels). LH, left hand; RH, right hand. B: individual values (colored circles) and mean value (black circles) for each condition. PreLH, pre-capsaicin, left hand; PostLH: post-capsaicin, left hand; PreRH: pre-capsaicin, right hand; PostRH: post-capsaicin, right hand.