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2.1. Virtual Reality Exposure Therapy
during which they were asked to look at a TV video in absence of the feared stimulus. They
then tested two different experimental conditions. In the first, they put the feared stimulus,
a live tarantula, right next to the safety area (the only exit to the room). In the second, they
introduced this feared stimulus away from the safety area. The phobic subjects reduced their
viewing of the video and increased their viewing of the feared stimulus and of the safety
area. Moreover, they made more eye motions across the room in which the experiment was
taking place. The authors concluded that their results were in line with previous studies and
that phobic people scanned the environment as part of safety behavior.
Certain types of ocular movements are symptomatic of specific illnesses or phobias. As
an example, tasks requiring saccadic eye movements can identify cognitive deficit in children
suffering from schizophrenia [Ross et al., 2005]. In this study, the authors tested Delayed
Oculomotor Response (DOR) on 187 children aged 5 to 16 years old. 45 of them
had childhood-onset schizophrenia, 64 had a first-degree relative with schizophrenia, and
84 of them were typically developing children. Their results showed that the children with
childhood-onset schizophrenia demonstrated impaired response inhibition and spatial accuracy
compared to the two other groups of children. However, there were no notable differences
between these two latter groups.
Smith used an ASL series 5000 eye-tracking device [ASL, 2009] combined with magnetic
head tracking to test the presence of hypervigilance and avoidance strategies in 46
undergraduate subjects [Smith, 2005]. The author hypothesized that socially anxious people
would demonstrate these vigilance-avoidance behaviors when exposed to disgust-faces
(threatening stimuli) but not when exposed to happy-faces (non-threatening stimuli). High
socially anxious subjects and low socially anxious ones did not differ in attention behaviors
towards the non-threatening stimuli. They did not differ in initial attention towards the threatening
stimuli either. However, high socially anxious subjects took more time to disengage
from this threatening stimuli. This study concluded that high socially anxious individuals
have a tendency to present delayed disengagement from social threat.
Herbelin described the use of eye-tracking to determine fixation periods on areas of interest,
as well as detect salient facial feature avoidance [Herbelin, 2005]. The author developed
a visualization tool to help therapists analyze their patients’ gaze behaviors. The author also
described a gaze map color coding method, depicted on the left of Figure 2.6. This method
allows the determination of which parts of a virtual character are being looked at or even if
the character is being looked at at all, and this, even when the characters are in movement.
The author conducted a case study using both these tools. He concluded that eye-tracking
could be very beneficial as it allows for therapists to confront the phobic subjects to their
gaze avoidance behaviors.
Finally, Mühlberger et al. developed the CyberSession software allowing them to manipulate
and navigate in a VE [Mühlberger et al., 2008]. They designed a virtual lift which
would stop at 60 floors of a building. At each floor level, the lift doors would open and
the user would face three different scenarios. In the first one, the user would face a happy
character and an angry one. This can be seen in Figure 2.6, right. In the second, the user
would face a happy character only and in the third one, an angry character only. The authors
used electroocculogram based eye-tracking combined with head tracking in order to allow
subjects to be free of movement. They tracked the eye movements of 26 students testing the
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