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6.2. Clinical Study on VRET for Social Phobia
Figure 6.2: Eye-tracking device, Left: eye-tracker. Right: subject wearing the device, seated in
front of the back-projection screen (Photo: Alain Herzog).
curacy calculations. Moreover, this type of sensor presents some drift after some time of
use. The rotations done by the head around the vertical and horizontal axes induce a rotation
around the sagittal axis. We thus have to recalibrate the system at regular intervals in order
to correct and cancel this extra rotation.
Finally, the last component of this setup is a large back-projection screen on which our
environments are displayed. This can be seen on the right of Figure 6.2. Its size is of
3.2 meters x 2.4 meters on which we display the scenes at a resolution of 1024 x 768. In
this setup, the subject is generally seated approximately 2 meters away from the screen, or
standing and walking around in its vicinity.
6.2 Clinical Study on VRET for Social Phobia
As preliminary work to that presented in this experiment, Herbelin et al. and Riquier et
al. have conducted a study during which they exposed subjects to a VR situation representing
a 3-dimensional audience composed of emergent gazes in the dark and surrounding the
subject [Herbelin et al., 2002; Riquier et al., 2002]. They experimentally confirmed that the
audience was able to provoke more anxiety to social phobics than to non phobics and emitted
the hypothesis that eye contact was an important factor of social phobia. Herbelin therefore
developed and experimented with an eye-tracking setup integrated in the VR system [Herbelin,
2005]. As mentioned in Chapter 2, he developed a tool that allows to determine not only
if virtual characters are being looked at, but which parts of the characters are being looked at
by a user wearing an eye-tracker.
We hereby describe the experiment we have conducted in order to validate his work and
the various scenarios we have discussed in Chapter 3.2.
The goal of this study was to define a therapeutic program for social anxiety disorders
using VR and to assess its efficacy in order to confirm that VR was a promising tool for
psychotherapists as part of social phobia treatment. We equally wanted to evaluate the use
of eye-tracking as a new tool for the assessment of social phobia and to see if the technology
could “provide therapists with an objective evaluation of gaze avoidance and can
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