Procedure
pain
After arriving at the lab, participants received information about the experiment, after which they signed an informed consent form and were screened for inclusion and exclusion criteria. If eligible, they continued with the experimental steps, starting with filling in psychological questionnaires (Qualtrics, Provo, UT), followed by participating in all measurements involving pressure stimuli. Nonpainful, slightly painful, and moderately painful pressure intensities were individually calibrated using the pressure pain device. After a successful calibration procedure, when participants were able to differentiate between the 3 pressure intensities, the experimenter opened the randomization envelope to randomly allocate participants to their respective experimental conditions for parts 1 and 2. Sham electrodes of the DNS device were attached to the arm, and further information was provided about the procedural steps in part 1. Twenty learning phase trials and 6 testing phase trials from part 1 followed. After a 10-minute break, participants received further instructions about the procedural steps in part 2. Again, 20 learning phase trials and 6 testing phase trials from part 2 followed. After the end of the experiment, the electrodes were removed from the arm, and participants were asked to fill in exit questionnaires, which were reported elsewhere.