134 trial after the first trial of evocation was used instead of the 30th trial after the start of attenuation, a 2x2 mixed model ANOVA showed no significant difference in resistance to extinction between conditioning with partial reinforcement versus continuous reinforcement (F (1,46) = 0.61, P = 0.44, ηp 2 = 0.01). Resistance to counterconditioning The mean reduction and mean magnitude of reported nocebo hyperalgesia after counterconditioning are listed in Table 2. We conducted a 2x2 mixed model ANOVA to examine whether conditioning with partial reinforcement resulted in nocebo hyperalgesia that was more resistant to counterconditioning, as compared to conditioning with continuous reinforcement. The analyses showed a significant difference in the resistance to counterconditioning between conditioning with partial reinforcement versus continuous reinforcement (F (1,47) = 4.99, P = 0.03, ηp 2 = 0.09). Figure 5 illustrates the differences in pain ratings for the first nocebo trial of the first evocation and the first nocebo trial of the second evocation, between the partial reinforcement-counterconditioning group and the continuous reinforcement-counterconditioning group. This finding indicated that partial reinforcement led to more resistance to counterconditioning than continuous reinforcement. Furthermore, two repeated measures ANOVAs showed a significant effect of trial type (first nocebo evocation trial pre attenuation, first nocebo evocation trial post attenuation) in the partial reinforcement group (F (1,24) = 15.96, P = 0.001, ηp 2 = 0.39) and the continuous reinforcement group (F (1,23) = 27.65, P < 0.001, ηp 2 = 0.54), indicating that counterconditioning significantly reduced nocebo responses in both groups.
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