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Chapter 6. Experimental Validations - Social Phobia Subject HSD - auditorium VSD - auditorium HSD - bar VSD - bar CA 81.42 / 76.03 97.49 / 39.02 62.11 / 50.48 58.00 / 38.07 CB 90.38 / 98.89 54.35 / 80.00 45.53 / 54.82 71.81 / 48.59 CC 42.94 / 43.06 39.75 / 43.78 11.35 / 23.49 <strong>20</strong>.03 / 33.21 CD 69.93 / - 85.31 / - 51.53 / - 48.21 / - CE 47.95 / - 38.64 / - 33.86 / - 83.92 / - Table 6.3: Standard deviation for control subjects. Pre-treatment / Post-treatment. Subject HSD - auditorium VSD - auditorium HSD - bar VSD - bar PA 27.02 / 71.00 24.03 / 40.38 35.38 / 64.51 41.43 / 43.02 PB 25.21 / 39.86 41.65 / 40.67 21.11 / 17.46 44.57 / 35.24 PC 77.77 / 74.60 83.63 / 48.34 75.89 / 64.95 102.07 / 65.05 PD 82.89 / - 58.07 / - 72.38 / - 70.68 / - PE 55.10 / - 19.43 / - 35.17 / - 39.05 / - Table 6.4: Standard deviation for phobic subjects. Pre-treatment / Post-treatment. clearly demonstrated hypervigilance. The subjects from the control group mostly looked at the central character in the first row, but also at the whole audience. On the other hand, only one of the five phobic subjects showed a visual behavior corresponding to the control group subjects’. Four of them focused on one or two characters only. This can be seen in the examples shown in Figure 6.8 where the phobic subject clearly concentrates on a single character whilst the control group one looks at the whole audience. We have also measured the standard deviation (SD) for each subject. As can be seen in Table 6.3, the values obtained from the control subjects are all above 40 for the horizontal component (HSD) and near 40 and more for the vertical component (VSD). These values are not surprising since looking at the whole audience, i.e., the whole width and height of the screen, translates to high SD values. Table 6.4, containing the data for the phobic group, shows that PC and PD have values similar to those of the control group. PB and PE have one of the two components which is significantly smaller in the pre-therapeutic phase and PA clearly has values very much below those of the control group in the pre-therapeutic phase. However, both PA and PB have values corresponding to those of the control subjects in the post-therapeutic phase. It is important to note that for this scene, the horizontal deviation is much more important than the vertical one due to the image properties; the virtual characters being mostly on the bottom part of the projected image but spread out over its width. In the second scene, the bar scene, since there is only one main character to which the subject is speaking, non-phobic subjects look at that person in the face, and more specifically, at that character’s salient facial features (eyes, nose and mouth). Numerically, this translates in small SD values. On the other hand, a phobic subject prone to visual avoidance behaviors will look at anything but salient facial features. All subjects from the control group mostly looked at that character in the face while talking to him. Four of the subjects from the phobic group equally behaved this way. Subject PC, however, clearly demonstrated an avoidance of the character’s salient facial features. 88
6.3. Eye-tracking as Assessment and Diagnosis Tool Figure 6.8: Eye contact behavior during exposure. Left: Phobic subject. Right: Control subject. Figure 6.9: Eye contact behavior during exposure. Left: Phobic subject. Right: Control subject. Figure 6.9 shows the eye-tracking results for PC and CB. Subjects PC and PD showed noticeably higher values than the other subjects in the pre-treatment phase. This means they did not stay focused on the character they were talking to but let their eyes wander. PD, however, did not show clear elusion of salient facial features as PC did. In the case of PC, these values have significantly decreased in the post-therapeutic phase. 6.3.3.2 Hyperscanning Another type of avoidance behavior present in some social phobic subjects is hyperscanning. Some social phobic subjects seem to be focused on the virtual character(s) present in the scene. However, they move their eyes in such a rapid way that it actually consists of a form of avoidance. In order to measure eye scan velocity, we first calculated the Euclidean distance between each set of two consecutive gaze points. We then averaged this data in order to obtain the mean distance covered at each time step, which can be interpreted as a velocity. Once again, there are no units to these distances since we use the raw data from the eye-tracking device. However, what we are interested in is to compare the results of phobic subjects with those of control subjects in order to verify whether there is a difference in 89
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Simulating Interactions with Virtua
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3.2.4 Scripts . . . . . . . . . . .
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7.3 Experimental Protocol . . . . .
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Résumé La Réalité Virtuelle (RV
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CHAPTER 1 Introduction 1.1 Context
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1.3. Contributions in areas of dail
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1.5. Organization of this Document
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CHAPTER 2 State of the Art 2.1 Virt
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2.1. Virtual Reality Exposure Thera
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2.2. Models of Visual Attention Fig
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2.3. Motion Editing Peters and O’
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2.3. Motion Editing Figure 2.10: Bi
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CHAPTER 3 VRET For Social Phobia Mu
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Page 123 and 124: APPENDIX A Ethics Commission Reques
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Page 131 and 132: APPENDIX B Fearful Situation Docume
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Page 135 and 136: APPENDIX D Glossary Acrophobia: acr
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List of Figures 6.3 Results to the
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Bibliography BIBLIOGRAPHY American
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Bibliography Dassault Systèmes. ht
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Bibliography Iscan. http://www.isca
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Bibliography A. Mühlberger, M.J. W
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Bibliography B.O. Rothbaum, L.F. Ho
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WHO. The ICD-10 Classification Of M
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