Temporal dynamics in the relation between presence and fear in virtual reality

Virtual reality (VR) is increasingly investigated as a new medium for exposure therapy, but process variables are not well understood. In particular, presence and fear during VR exposure correlate strongly, but the causal relationship between them remains unclear. We assigned 22 female spider-fearful participants randomly to either a stereoscopic (high presence) or a monoscopic (low presence) condition and exposed them repeatedly to a large virtual spider presented on a Powerwall. Presence and fear were assessed on subjective, physiological, and behavioral levels. Fear reactions were stronger and presence ratings were higher in the stereoscopic than the monoscopic condition. Presence in the first exposure trial correlated significantly with fear in the second exposure trial, while fear in the first exposure trial did not correlate significantly with presence in the second exposure trial. For the following exposure trials, correlations between presence and fear were significant in both directions. Limitations of our study include the small sample and the fact that we did not check diagnostic criteria of specific phobia. This is the first study to show temporal dynamics of the relationship between presence and fear. Initially, presence in VR seems to directly influence fear, while over time, presence and fear appear mutually dependent.