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Chapter 7. Experimental Validation - Agoraphobia
Finally, we analyzed the eye-tracking data for the 10 participants who wore this device.
We have not noticed any difference in the types of assessments to the various questions we
have asked between users who wore the combined eye- and head-tracking device and those
who wore the head-tracking device only. Eye-tracking therefore does not seem to have a
significant added value in the determination of a user’s gaze direction. As mentioned at the
beginning of this chapter, we also analyzed eye scan velocity and pupil dilation. Indeed,
hyperscanning is a symptom found in people suffering from social phobia [Horley et al.,
2004] and pupil size is known to increase with anxiety [Marks, 1987]. Our results, however,
were not probing. We did not obtain any correlation between eye scan velocity, pupil dilation
and the subjective ratings to the questions we asked. However, this is probably due to the
fact that we did not deal with a phobic population. We believe that both eye scan velocity
and pupil dilation could actually be very good indicators of the presence of increased anxiety
depending on the various modes in agoraphobic patients. However, we would need to test
our application on such a population to confirm these hypotheses.
7.5 Discussion
Simulation related problems. We have encountered several problems in the display of our
simulation which have interfered with the features we wanted to evaluate. First, there was
no collision detection between characters and with the user. They thus collided with and
intersected the user from time to time. For some participants, this considerably reduced their
evaluation of character awareness. Here as well, we can mention the uncanny valley effect as
there were clearly inconsistencies between character appearance and behavior. Moreover, the
frame rate being quite slow due to the complexity in the four-screen display, the scene lagged
from time to time, which we believe provoked a decrease in the feeling of immersion. Finally,
also due to those quite slow frame rates, we had to display our characters in a lower level of
detail. They thus lacked facial animation, which we also believe considerably reduced the
feeling of immersion.
Combination of gaze and gesture. When we evaluated our application, we allowed for
the users to interact with the characters using both gaze and gesture. We believe that we
should have evaluated these two forms of interaction separately. Indeed, some participants
were distracted by the waving and thus did not pay very much attention to the gazing behaviors.
Moreover, when the gesture was not recognized, the characters did not respond. Some
participants’ evaluation of awareness and friendliness therefore suffered from this.
Computation of Interest Points. We have seen from our results that even though the characters
were looking at each other in the random mode, the participants did not perceive their
awareness towards each other. We believe this is due to a random choice of interest points
to look at instead of a logical one. We thus think that this mode of the application could
greatly benefit from the implementation of an interest point detection algorithm as the one
we presented in Chapter 4.
Validation with a phobic population. Nevertheless, we believe our application to have a
high potential in the treatment of agoraphobia with crowds. We believe that it could prove
to have very high immersive qualities. Moreover, the application allows the definition of the
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