Calibration
shock, pain
SHOCKS, SHOCK
First, participants were asked to report three levels of their individual pain intensity—low, moderate, and high. They were falsely told that the calibration was aimed at tailoring an individual shock intensity level, which will remain fixed during the study. The intensity of the electric shocks was gradually increased by the experimenter until participants reported a low intensity level, namely, slightly unpleasant, requires little effort to tolerate, and equals the number 2 on a 1 (= minimally painful) to 10 (= unbearable) pain intensity scale. Then, the intensity was further increased until participants reached a moderate intensity level, namely, more unpleasant and requiring more effort to tolerate, relative to the low intensity, and equals the number 5 on the pain intensity scale. Last, the intensity was further increased until participants reached a high intensity level, namely, intense and requiring more effort to tolerate, relative to the moderate intensity, though still at a tolerable level, and equals the number 8 on the pain intensity scale. Importantly, the low and the high intensity levels were later used in the conditioning phase, for the placebo-distraction and the control-distraction blocks, respectively. The moderate intensity was used for the baseline no-regulation (experience) phase, the test phase, and the choice phase.