120 stimuli were calibrated. Participants then underwent nocebo induction through conditioning with partial reinforcement, continuous reinforcement, or sham conditioning. The first evocation phase where nocebo responses were tested then followed. Subsequently, participants underwent nocebo attenuation, through either counterconditioning or extinction. A second evocation phase then followed, where the presence of nocebo responses after attenuation was tested. After the end of the experiment participants were asked to complete the exit questionnaire. Then, a debriefing was conducted and participants were reimbursed for their participation. Statistical Analyses All data were analyzed by use of SPSS 23.0 (IBM Corp., Armonk, NY, USA). A one-way analysis of variance (ANOVA) was conducted between all groups for mean scores on each of the questionnaires and the tiredness rating, in order to determine whether any personal characteristics could have influenced the results. One-way ANOVAs were also used to assess between-groups differences in state anxiety, trust in the experimenter, and pain expectations, as assessed at the end of the experiment and in temperatures used to induce pain and the NRS pain scores throughout the experiment. As these analyses involved multiple between-groups comparisons, the threshold for significance was set at P < 0.01. Primary and secondary outcome measures The magnitude of reported nocebo hyperalgesia (primary outcome measure) was measured within-subjects, and was defined as the difference in pain ratings for the first nocebo trial compared to the first
RkJQdWJsaXNoZXIy MTk4NDMw