Figure 1.
CONSORT Flowchart.
Figure 2.
All subjects first receive identical baseline stimuli on three spots of their right arm. Conditioning groups were then given a verbal suggestion specific to their conditioned audio target, while the no-conditioning group was given a neutral suggestion. All groups then received four blocks of two stimulus intensities, with levels determined during Session 1 (target levels = 20–40 out of 100 and 55–70 out of 100 on the pain intensity VAS). Conditioning groups received lower heat levels when the conditioned audio stimulus was on, while the no-conditioning group received stimuli with silence. All groups were then tested with three audio conditions: music, sound, and silence, in randomized order across participants. Within each set of trials, lead-in arrows represent 1 minute of audio or silence that preceded the start of pain stimuli. In all groups ERS was assessed right after verbal suggestion, then following conditioning/variable pain, and after testing (red arrows). We added one more baseline ERS assessment within the music conditioning replication group at the end of session 1 (orange arrow).
Figure 3.
Average pain intensity and unpleasantness changes, all original groups.
N = 35. Shown here are pre (baseline) minus post (testing) pain difference scores (mean ± SEM); positive values indicate analgesia. Panel A displays Pain Intensity, panel B displays Pain Unpleasantness.
Table 1.
Average Pain Ratings for all Groups.
Figure 4.
Average expectancy scores in all original groups, across all ERS assessment points
. Means ± SEM are shown for N = 35. Time 1 occurs after verbal suggestion but prior to the conditioning phase in the conditioning groups, and prior to the matched variable pain phase in the no- conditioning group. Time 2 occurs immediately after the conditioning/variable pain phase, and Time 3 occurs after testing.