140 statistically significantly larger resistance to extinction after partial, as compared to continuous reinforcement. Extinction trends pointed towards partial reinforcement resulting in more durable nocebo responses compared to continuous reinforcement, as illustrated in Figures 4 and 6, however this difference was not significant. Moreover, it was observed that during attenuation, pain reports in the partial reinforcement group did remain consistently higher than those in the continuous reinforcement group (Figure 6), despite the fact that after induction, partial reinforcement produced a significantly weaker nocebo response than continuous reinforcement. The effectivity of extinction even after partial reinforcement could be explained by the fact that exposure to extinction was longer than exposure to nocebo induction, when considering the first evocation phase. It is worth pointing out, however, that in real-word contexts, patients may be exposed to shorter periods during which nocebo hyperalgesia is acquired and longer periods of extinction. As such, the current model provides novel evidence that nocebo hyperalgesia can be extinguished over prolonged exposure to extinction, even after partial reinforcement learning. Interestingly, a partial reinforcement resistance effect was found when attenuation involved counterconditioning. Counterconditioning was still successful in attenuating nocebo effects after conditioning with partial reinforcement, however, counterconditioning was observed to be substantially more effective after conditioning with continuous reinforcement (Table 2, Fig. 5). Importantly, this effect was observed despite the fact that partial reinforcement had resulted in a significantly weaker nocebo response. This counterconditioning-specific resistance effect could be attributed to negativity bias (i.e., the tendency to attend to or remember negative experiences over neutral or positive experiences 41–43). According to this theory, when provided with inconsistent positive and negative information about the same stimulus, individuals are more likely to retain the negative information 44. A negativity bias may have taken place following the ambiguous
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