Subjective evaluation of nonpainful warm stimulus in uncertain condition (NPS-u) and nonpainful warm stimulus in certain condition (NPS-c). Scores of individual subjects and mean scores across all subjects are shown. Diagonal line indicates equal scores for NPS-u and NPS-c conditions. Subjects rated intensity and unpleasantness of each stimulus separately. The unpleasantness score of NPS-u was significantly higher than that of NPS-c, whereas the intensity scores did not show a significant difference between the two conditions. Statistical analysis was conducted with Wilcoxon signed rank tests.