Mia Thomaidou

132 Resistance to extinction The mean reduction and mean magnitudes of reported nocebo hyperalgesia after extinction 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 extinction, as compared to conditioning with continuous reinforcement. A non-significant interaction effect showed no significant difference in resistance to extinction between conditioning with partial reinforcement and continuous reinforcement (F (1,46) = 0.63, P = 0.43, ηp 2 = 0.01). Figure 4 illustrates 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-extinction group and the continuous reinforcement-extinction group. 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 (1,23) = 5.26, P = 0.03, ηp 2 = 0.19) and the continuous reinforcement group (F (1,23) = 10.39, P = 0.004, ηp 2 = 0.31), indicating that extinction significantly reduced nocebo responses in both groups.

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