194 recording session at a laboratory of the Faculty of Social and Behavioral Sciences of Leiden University, the Netherlands. All participants provided written informed consent prior to participation. After completing the experiment, all participants were reimbursed by either study credits or cash. The study was approved by the Leiden University Psychology Research Ethics Committee (CEP19-1031/532; all methods and procedures were performed in accordance with the relevant guidelines and regulations) and pre-registered on ClinicalTrials.gov (NCT04199858, 16/12/2019; planned analyses of frequency biomarkers were not conducted due to the scope of this paper). Experimental design This study utilized a within-subjects design. All participants underwent 1) a calibration phase, 2) a baseline phase, and a nocebo phase comprising 3) nocebo acquisition and 4) nocebo evocation (Fig. 1a). During the first phase, calibrations for warmth and pain perception were conducted. During the baseline phase, moderate- and high-pain stimuli were administered. During nocebo acquisition, a conditioning procedure took place, in which associations were learned between the nocebo treatment and higher pain. Participants were conditioned to associate a sham pain-increasing gel with high (increased) pain stimulations, and no gel (control) with moderate-pain stimulations. During nocebo evocation, these learned associations were tested. Thermal pain application Thermal pain stimuli were delivered to the volar forearm using a Thermal Sensory Analyzer with a 3×3 cm ATS thermode probe (TSA-
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