Mia Thomaidou

178 Exploratory and Manipulation checks In an exploratory manner, we examined how fear responses influenced the acquisition and extinction of nocebo hyperalgesia. Pearson’s correlation analyses across all groups showed significant correlations between reported fear (difference between nocebo and control trials) and the magnitude of nocebo responses (r = 0.59, P < 0.001), as well as between reported fear and the magnitude of nocebo responses still present after extinction (r = 0.33, P = 0.002). Figure 8 illustrates the two correlations. Table 3 lists all correlations between the magnitude of reported fear and the magnitude of nocebo responses for each group and each experimental phase. Finally, we ran analyses to explore any relationships between nocebo responses, fear responses, and related psychological or cognitive factors. Exit questions and psychological questionnaires On average, participants believed the information they received during the study (M = 8.6, SD = 1.8), they thought the researcher was honest (M = 8.7, SD = 1.5), they were not concerned about what the researcher thought of them (M = 3.3, SD = 1.7), and they were focused on the heat tests (M = 8.7, SD = 1.1). We ran Pearson’s correlations between the magnitude of nocebo hyperalgesia and manipulation check exit questions. Participants’ expectations about pain during nocebo trials differed per group (Control: M = 5.6, SD = 1.7; High-pain: M = 6.9, SD = 1.7; High-threat: M = 6.2, SD = 1.9) and pain expectations across all groups were correlated to nocebo magnitudes (r = 0.38, P < 0.001). None of the other responses to exit questions where significantly correlated with the magnitude of nocebo responses (for all questions P > 0.05, please see supplementary material). A one-way ANOVA showed that there were no significant group differences in questionnaire scores

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