Fig. 1.

Trial structure. Each trial began with an instruction screen (“cue”; 3 s), informing participants about the predictive relationship between S1 and S2 and whether pressing the response button would affect S2. A fixation cross (2 s) then appeared onscreen, followed by the delivery of a painful or nonpainful stimulus (S1; 2 s). Participants’ task was to press a response button upon the presentation of a cue (a dot), which was displayed 1 s following the onset of S1 for a duration of 450 ms. S1 was followed by a jittered ISI of 4–6 s with a fixation cross display, then by suprathreshold painful or nonpainful stimulation in S2 (1 s or 4 s, depending on action effectiveness and participants’ response). ITI duration varied depending on the duration of the trial and the ramping time of the stimulating thermode (ITI range: 3.56–16.86 s). S1 = stimulation 1 (“current pain”), S2 = stimulation 2 (“predicted pain”).