Efficacy of a VR Paradigm to Reduce Fear of Heights in a Clinical and Subclinical Population With Fear of Heights

Change in BAT performance after VR exposure from baseline (before VR exposure). During the BAT participants will be requested to climb up to the Uetliberg Tower while continuously looking to the ground level. Participants will be asked to only proceed as far as their anxiety allows them. On each of the 14 platforms participants will be asked to lean on a predefined area of the railing (and touch it with their upper body) and to look down to the ground for 10 seconds, if their fear allows them to do so. The BAT will be terminated as soon as the participant indicates feeling uncomfortable to proceed (adapted from Emmelkamp, 2002 and Coelho, 2006) or the 10 minutes period, given to them to perform the complete task, runs out.

Change in AQ after VR exposure from baseline (before VR exposure).This questionnaire describes twenty situations that can cause fear of heights (e.g., driving over a bridge, walking over a sidewalk grating, or sitting on an airplane) and asks for anxiety ratings on a 7-point Likert-type scale (0 = not at all afraid to 6 = very afraid, range 0-120, α = 0.80) (Cohen, 1977).

Change in ATHQ after VR exposure from baseline (before VR exposure).The ATHQ consists of six questions assessing participants' attitudes towards heights situations (e.g., "I think heights are … good - bad, secure - insecure"). Patients evaluate their attitudes towards heights by twelve adjectives on an 11-point scale ranging from a positive (0) to a negative (10) adjective (range 0-60; α = 0.81).

Change in AES after VR exposure from baseline (before VR exposure). The AES assesses anxiety symptoms in a height situation. The AES consists of ten items describing anxiety symptoms (e.g., "you could feel dizzy"). Participants rate the likelihood of experiencing these symptoms while being in a height situation on a five-point scale (range 10-50) (Gursky & Reiss, 1987).

The DES assesses dysfunctional cognitions. The DES consists of five items. Participants rate the likelihood that each of the listed harmful events (e.g., "you might slip and fall over the guard rail on the observation deck") will pass through their minds while being in a height situation on a five-point scale (not likely at all (1), probably not (2) maybe (3), quite likely (4), or definitely (5), range 5-25) (Gursky & Reiss, 1987).

The VR exposure app acceptability and usability scale consists of 10 items (study phase 1)/11 items (study phase 2) that assess the overall acceptability and usability (e.g. design, functionality) of the VR app. The items were solely composed for our study purposes. The first 9 items will be assessed through a 11-point scale, item 10 and 11 have an open answer format. Higher scores indicate higher acceptability and usability.

The IPQ assess participants' presence while being in VR. The IPQ consists of 14 items with a 7-point scale (0-6) that concern the participants' sense of being in the virtual environment, for example, the extent to which virtual reality was "real" to them, whether they thought of the virtual environment more as images they saw or more as a situation they were in, how much attention they paid to the real world, and the extent to which they focused on the virtual task. The IPQ consists of three subscales: Spatial Presence (range 0-30), Involvement (range 0-24), Realness (range 0-12), higher scores indicate stronger presence (Schubert, 2003).

Participants in the experimental group will be prompted to give their SUDS during the VR heights exposure sessions at predefined time points (first rating on each level after 10 seconds, then every 30 seconds until allowed to enter the next level. Then again first rating after 10 seconds, then every 30 seconds until allowed to enter the next level and so on (scale 0=no fear to 10=extreme fear).

Assessment of potential side effects of VR immersion. Possible symptoms (e.g. headache, nausea) will be assessed directly before (baseline) and after the VR exposure on a scale between 0-3. The change from baseline will be evaluated.