Study procedure
COVID-19 INFECTION
Eligibility was determined in a semistructured telephone interview with interested individuals prior to being invited to the lab. Since the study was conducted during the COVID-19 pandemic, the participants were called on the eve of the laboratory appointment to verify that they were not experiencing symptoms of COVID-19 infection. The experimenter wore a white lab coat and an FFP-2 mask during the whole lab session and followed further hygiene regulations such as 1.5 m distance and extensive room disinfection. Participants were tested in a lab with the experimenter in the same room, so that the participants could communicate with the experimenter at any time. The laboratory session followed a standardized protocol. After giving informed consent, participants were asked to complete the questionnaires during the lab session using an online survey platform (Unipark; Questback, 2018); they received information about OLP and were randomly assigned to one of four groups, as shown in Fig. 