Experimental procedures
warmness of voice
Participants were invited for a single session at our VR lab. They were informed that they would try the introductory part of a VR therapy for fear of heights. After obtaining written consent to participate in the study, the researcher first demonstrated the use of VR and helped participants fit the VR headset. Later, the researcher selected the parameters for the VR experience according to each participant’s condition group and they experienced the indoor scene. Once that stage ended, participants took the VR headset off and completed the measures of therapeutic alliance, warmness of voice, treatment credibility/expectancy, and presence. The outdoor scene was a virtual heights experience and could elicit anxious feelings for people with fear of heights. The researcher made sure that participants knew beforehand they could stop the VR scene at any time. Participants experienced the outdoor VR scene and then completed the presence and mistrust questionnaires. Finally, they were fully debriefed about the purpose of the study. The entire session lasted approximately 45 min, and participants were reimbursed for their time. Figure Study procedure.