Chapter 4 – Experimental learning 123 however, are identical to extinction trials. This exposed participants to a longer extinction time (i.e., essentially 40 trials), as compared to the 30 induction trials. In order to verify that any extinction or resistance effects were not present after an equal number of induction and extinction trials, we analyzed the 30th trial after the start of evocation. A 2x2 mixed model ANOVA was performed with the induction group as between-subjects factor with two levels (partial reinforcementextinction, continuous reinforcement-extinction) and the nocebo response during extinction as the within-subjects factor with 2 levels (20th nocebo extinction trial, 21st control extinction trial). Resistance to counterconditioning It was also assessed whether a resistance effect to counterconditioning was present. A 2x2 mixed model ANOVA was performed with induction group as the between-subjects factor with 2 levels (partial reinforcement-counterconditioning, continuous reinforcementcounterconditioning) and nocebo response as the within-subject factor with 2 levels (first nocebo trial of the first evocation phase preattenuation, first nocebo trial of the second evocation phase postattenuation). Following this, two repeated measures ANOVAs were conducted with the nocebo response as the within-subjects factor with 2 levels (as described above), to test whether counterconditioning significantly reduced the magnitude of nocebo hyperalgesia within partial reinforcement and within the continuous reinforcement group. Time-course of attenuation To explore the time-course and slopes of attenuation, a line graph was plotted. Mean NRS pain ratings were plotted for the nocebo trials after
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