Figure 1.

Experimental design. a. Conditions of interest. During the first two blocks of the task, low-pain cues always preceded low-pain stimulation (LL) and high-pain cues preceded high-pain stimulation (HH). During the subsequent six test blocks, trials were evenly divided between these conditions and trials in which each predictive cue was followed by a stimulus calibrated to elicit medium pain [high cue plus medium pain (HM); low cue plus medium pain (LM)].

b. Trial structure. Each trial consisted of an auditory predictive cue followed by an anticipatory delay and 5 s of noxious thermal stimulation. After a 5 s average interstimulus interval, participants reported trial-by-trial perceived pain using a visual analog scale.