Post hoc ratings of stimulus and task characteristics for chronic pain patients and healthy controls
| Stimulus intensity | Stimulus unpleasantness | Stimulus salience | Task difficulty | Task preference | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Pain | Touch | Pain | Touch | Pain | Touch | Pain | Touch | Pain | Touch | |
| Patients mean (±SD) | 5.5 (±2.4) | 4.1 (±2.4) | 4.7 (±2.8) | 1.1 (±1.4) | 7.2 (±1.8) | 4.6 (±2.7) | 3.7 (±2.7) | 3.6 (±2.6) | -1.2 (±4.2) | -1.9 (±4.5) |
| Controls mean (±SD) | 5.2 (±2.4) | 3.6 (±2.8) | 3.8 (±2.3) | 0.8 (±1.1) | 6.5 (±2.1) | 4.7 (±2.4) | 2.4 (±1.5) | 2.4 (±2.1) | -0.3 (±2.6) | 0.0 (±3.3) |
For stimulus intensity/unpleasantness/salience, VAS was anchored at 0 = not intense/unpleasant/salient and 10 = highly intense/unpleasant/salient. For task difficulty, VAS was anchored at 0 = not difficult and 10 = very difficult. For task preference, VAS was anchored at –10 = very focused on the reaction and 10 = very focused on the rating. VAS, visual analog scale. For intensity, unpleasantness, and salience, ANOVAs showed a significant main effect of modality (Fintensity(1,40) = 18.7, Funpleasantness(1,40) = 37.5, Fsalience(1,40) = 24.9, all p < 0.001) but not of group (Fintensity(1,40) = 0.23, Funpleasantness(1,40) = 0.55, Fsalience(1,40) = 0.05, all p > 0.05) and no interactions between group and modality (Fintensity(1,40) = 0.15, Funpleasantness(1,40) = 0.02, Fsalience(1,40) = 0.06, all p > 0.05). For task preference, ANOVA did neither show a significant main effect of group (F(1,42) = 1.3, p > 0.05) or modality (F(1,42) = 1.1, p > 0.05) nor an interaction between group and modality (F(1,42) = 2.4, p > 0.05). For task difficulty, ANOVA showed a significant main effect of group (F(1,42) = 5.0, p = 0.031) but not of modality (F(1,42) = 0.53, p > 0.05) and no interaction between group and modality (F(1,42) = 0.42, p > 0.05).