Therapist-guided virtual reality exposure therapy for fear of heights: evidence from a multiple-baseline single-case experimental design

Virtual reality exposure therapy (VRET) has demonstrated efficacy for specific phobias, yet most platforms separate the therapist from the patient during exposure. This multiple-baseline single-case experimental design study (SCED; n = 3) examined a multicomponent therapist-led VRET intervention delivered in an original collaborative immersive virtual environment (CIVE) developed for fear of heights treatment. Three adults from the general population with fear of heights completed unguided baseline sessions, therapist-led CIVE intervention sessions, and self-led follow-up sessions conducted three weeks after the intervention. The intervention combined repeated VR exposure, shared therapist-participant presence inside the CIVE, therapist guidance, and real-time heart rate (HR)-informed support. HR was monitored across all phases, but it was integrated into real-time therapeutic guidance only during the intervention phase. Outcomes included maximum height reached, State-Trait Anxiety Inventory, Form Y-1 (STAI-Y1), Subjective Units of Distress Scale (SUDS), and HR. Descriptive and visual analyses suggested preliminary, heterogeneous trends toward higher maximum floors reached and lower self-reported anxiety during the therapist-led CIVE intervention phase. These patterns were more apparent for two participants, while one participant showed delayed improvement. Follow-up data suggested possible maintenance of gains. Exploratory analyses of HR-height coupling showed a mixed pattern, including a statistically significant reduction in coupling in one participant, a non-significant trend in another, and no evidence of reduced coupling in the third. Overall, the findings provide preliminary indications that a multicomponent therapist-led CIVE intervention may support exposure progress in some individuals with fear of heights. However, larger controlled studies are needed before conclusions about effectiveness can be drawn, and to isolate the contribution of individual intervention components.