124 the end of nocebo induction, in the partial reinforcementcounterconditioning group, the partial reinforcement-extinction group, the continuous reinforcement-counterconditioning group, and the continuous reinforcement-extinction group. Manipulation-check for control trials We ran manipulation checks to examine any effect of changes in control trial ratings on the reduction of nocebo responses after attenuation. This was done to assure that the effects of attenuation were not driven by changes in the ratings of control trials (TENS off), which could confound the results, for example if between-groups differences were detected, or in the case that general sensitization or habituation to pain had occurred. First, an analysis of the control trial ratings in all groups was performed. A 5x2 mixed model ANOVA was performed with group as the between-subjects factor with 5 levels (groups 1, 2, 3, 4, and 5), and the first control trial rating of each evocation phase as the withinsubjects factor with 2 levels (control pre-attenuation, control postattenuation). As this analysis involved multiple between groups comparisons, a conservative Bonferroni correction was applied and the threshold for significance was set at P < 0.01. A non-significant result would indicate that the control trials did not yield significant changes, confirming that they did not affect the within-subjects results of the analyses. Furthermore, we conducted a 2x2 mixed model ANOVA between the attenuation groups (counterconditioning, extinction) and the pre- to post- attenuation difference score between nocebo and control trials. In this way, we examined the reduction in the magnitude of nocebo hyperalgesia from pre- to post- attenuation, by directly comparing control trials to nocebo trials.
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