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Chapter 6. Experimental Validations - Social Phobia Subject auditorium bar auditorium bar CA 8.98 8.34 8.71 7.16 CB 6.09 6.45 6.61 8.31 CC 1.97 1.64 3.59 4.40 CD 8.14 8.46 - - CE 5.77 7.52 - - Table 6.5: Eye scan velocity for control subjects. Left: Pre-treatment. Right: Post-treatment. Subject auditorium bar auditorium bar PA 5.21 6.82 6.50 7.67 PB 8.60 11.16 7.41 7.40 PC 10.37 10.93 11.66 11.14 PD 10.14 11.20 - - PE 4.32 4.00 - - Table 6.6: Eye scan velocity for phobic subjects. Left: Pre-treatment. Right: Post-treatment. behavior between the two. Thus, given that POHi is the horizontal component of the POR at frame i and that POVi is its vertical component, we compute the velocity v as: n i=0 (POHi − POHi+1) v = 2 +(POVi + POVi+1) 2 (6.1) n As can be seen in Tables 6.5 and 6.6, not all phobic subjects present hyperscanning behavior. PC and PD have scan rates above 10 for the auditorium scene whilst none from the control group attained such values in the pre-therapeutic phase. For the bar scene, PB, PC and PD all have scan values above 10. However, in the post-therapeutic phase, PB has values similar to those from the control group subjects in both scenes. On the other hand, PC demonstrates very high scan rates both before and after therapy. It should be noted that there is a high variability in the results of the control subjects. More specifically, CC demonstrated very low eye scan velocity. We can thus reasonably assume that some of the phobic subjects presented hyperscanning behaviors but can not affirm it. 6.3.3.3 Eye blinks Normal blinking rates are very different depending on the type of action being undertaken. Doughty et al. conducted tests on a set of people in different contexts: a reading context, a primary gaze context and a conversational context [Doughty, 2001]. Their results show that eye blink rates are much higher in conversational contexts than in other ones. Since our study concentrates on public speaking exercises, we have retained the average values for normal people in a conversational context. This rate is of 23 eye blinks per minute in average but can vary anywhere between 10.5 and 32.5 eye blinks per minute. The eye blink lasts between 100 and 400 milliseconds, which averages to 250 milliseconds [Schiffman, 2001]. Moreover, eye blinks rise with anxiety and tension [Kanfer, 1960]. 90
6.3. Eye-tracking as Assessment and Diagnosis Tool Subject Auditorium - Rate Auditorium - Duration Bar - Rate Bar - Duration CA 50.90 / 68.89 224 / 185 62.24 / 19.12 139 / 202 CB 24.96 / 21.11 250 / 157 33.61 / 17.13 166 / 199 CC 6.26 / 16.71 161 / 110 3.81 / 17.99 80 / 183 CD 45.20 / - 240 / - 41.69 / - 143 / - CE 32.14 / - 153 / - 34.82 / - 274 / - Table 6.7: Eye blink rates per minute and durations in milliseconds for control subjects. Pretreatment / Post-treatment. Subject Auditorium - Rate Auditorium - Duration Bar Rate Bar Duration PA 50.47 / 55.82 168 / 138 56.17 / 55.74 157 / 117 PB 82.62 / 71.27 89 / 96 92.23 / 72.65 73 / 93 PC 38.91 / 38.58 517 / 271 51.12 / 62.69 432 / 345 PD 48.38 / - 195 / - 67.13 / - 259 / - PE 23.89 / - 168 / - 22.71 / - 147 / - Table 6.8: Eye blink rates per minute and durations in milliseconds for phobic subjects. Pretreatment / Post-treatment. As shown in Tables 6.7 and 6.8, the average number of eye blinks per minute for the phobic subjects and control group subjects are high when compared to the averages as described by Schiffman [Schiffman, 2001]. We believe this is due to the equipment used. Indeed, we have noticed that after 10-15 minutes of eye-tracking use, people started feeling fatigue in their eye. We thus believe that the eye blink rate comes to be increased due to this fatigue. In the pre-therapeutic phase, PA and PB both had a rate above 50 eye blinks per minute in the first exercise and PA, PB, PC and PE all had rates above 50 in the second exercise. In the case of the control group, only CA had blink rates above 50 blinks per minute in both exercises. In the post-therapeutic phase, we have not noted any noticeable difference in this behavior; PA and PB both have values above 50 in the first scene and PA, PB and PC all have values above 50 in the second scene. Concerning eye blink durations in the pre-therapeutic phase, PC had blink durations of 517 milliseconds and 432 milliseconds whilst the highest values in the control group were of 250 milliseconds and 274 milliseconds for the first and second scenes respectively. Figure 6.10 shows a sample of 10 seconds for subjects CB and PC, both for the bar scene. In the post-therapeutic phase, however, PC demonstrated an important decrease in eye blink durations. Moreover, these values are within the range of 100 − 400 milliseconds. Once again, due to the diversity of our tested population and high variability in results, we can reasonably assume that some phobic subjects presented unusually high blink rates and durations but we can not affirm it. 6.3.3.4 Subjective ratings Out of the three phobic subjects who went through the complete therapy, PA and PB both had visible improvements in their responses to the various scales they filled out before and after treatment, i.e., the Liebowitz social anxiety questionnaire, the SISST, the BDI, and the 91
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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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CHAPTER 3 VRET For Social Phobia Mu
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3.2. Creating Scenarios For VRET Fi
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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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