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6.4. Eye-tracking for Interaction
to the subjects than any other. We believe this is due to a potential bias of the subjects towards
the expectation of an “always attentive” virtual character.
Confirmation of the second hypothesis. From the results we obtained with the healthy
subjects, we have been able to confirm our second hypothesis; that a character changing
behavior with respect to human eye contact behavior seems more normal than a character
that randomly changes behavior.
Bias on character behavior. As mentioned, we believe that there was a bias towards an
always attentive virtual character in the case of healthy subjects. However, interestingly
enough, this bias was reversed in the case of the young girl suffering from Asperger syndrome.
Indeed, she thought that it was normal for the character to seem uninterested and
distracted. It has to be noted that the healthy subjects were exposed for a shorter amount of
time than the case study subject. This bias towards always attentive behaviors may thus have
decreased in the case of a longer exposure.
Testing on a phobic population. In this experiment, we have tested our application on
healthy subjects mainly. The case study we have conducted on a young patient suffering
from Asperger syndrome, however, gave very promising results. Our application should
therefore be tested on a phobic population in order to evaluate its efficacy. Moreover, it
would allow us to verify whether the same bias towards uninterested and distracted virtual
characters would be present in such a phobic population as was seen in our case study.
6.4.5 Conclusion
In this section, we have described the experiment we have conducted over 12 healthy subjects
and the results we have obtained from their subjective feedback regarding the realism of
the character behaviors in 4 different situations: always bored, always attentive, randomly
animated, and animated with respect to the subject eye contact behavior. We have also tested
our application on a young girl suffering from Asperger syndrome. In this case study, we
used a hybrid approach where the character changed behavior either when triggered by hand
or with respect to the subject’s eye contact behavior in order to be able to force the character’s
attention at the beginning of the exposure session.
The results we have obtained on the healthy population have partially confirmed our first
hypothesis and fully the second. The subjects clearly identified the different behaviors but
seemed to be biased towards an always attentive character. Concerning the case study, this
bias was reversed. She expected the virtual character to be uninterested. During exposure, the
subject reacted very strongly to character behavior change. She clearly identified the change
and was affected by it. Moreover, the eye-tracking measures corroborated her impressions
during the exposure session. This demonstrates the potential of closing the loop to reveal
and trigger more elaborate interactions between the users and the virtual characters.
We strongly believe that this new form of interaction based on gaze behavior will greatly
amplify immersion and thus, the potential of VRET for the treatment of social phobia. We
believe that such a tool, that can induce such a positive feedback loop, can be of great help to
therapists in the treatment of social phobia by CBT. More specifically, we think that it could
be used to make patients understand that they can change people’s behaviors with their own.
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