Cybersickness in Persons with Multiple Sclerosis
Cybersickness or visually/virtually induced motion sickness is reported by many users when exposed to Virtual Reality (VR) since the birth of VR technology. Symptoms of cybersickness are similar to motion sickness such as fatigue, dizziness, nausea, etc. Systems aspects of cybersickness are considerably mitigated with the advancement of hardware technology but individual factors are still challenging the advancement of VR. Although there have been many cybersickness studies conducted, very few of them have focused on persons with disabilities. Inclusion of these persons in cybersickness studies is important because discomfort caused by VR-exposure could have negative effects on the VR-based rehabilitation system's effectiveness with addition to the limited accessibility of VR. This is one of the pioneering cybersickness studies concerning persons with disabilities. Therefore, exploratory studies had to be performed to find out how differently persons with disabilities experience cybersickness than persons without disabilities. Specifically, persons with disability caused by Multiple Sclerosis (MS) were compared to persons without disabilities. Subjective questionnaire feedback (e.g.; Simulator Sickness Questionnaire) and objective physiological characteristics (e.g.; Heart Rate, Breathing Rate, etc.) have been compared between groups and within groups. All participants experienced the same virtual reality simulation. Heart rate, breathing rate, galvanic skin response, and brain signals were recorded before, during and at the end of VR-exposure to compare physiological aspects between groups and within groups. Simulator sickness questionnaire feedback was recorded before and after VR-exposure. The physiological data suggest that the cybersickness may have triggered similar changes in participants with MS and participants without MS, with different variability. These differences in severity of physiological changes ask an important question - will cybersickness reduction techniques, developed for persons without disability (e.g.; use of static rest frame, postural adjustments, etc.) be equally effective for persons with disabilities? To answer that question, I have investigated the effectiveness of Static Rest Frames (SRF) to reduce cybersickness in persons with MS. All the participants (with MS and without any disability) experienced a roller coaster simulation with and without SRF. Then their subjective feedback and physiological measures were compared between subjects and within-subjects. As far as SRF is concerned, cybersickness reduction technique had an interesting impact on persons with MS. Their subjective feedback, SSQ was worse with SRF than No-SRF. Their physiological changes were somewhat similar to persons without MS but the severity was always different. From my research, I can deduce that the persons with MS (representing persons with neurological disability) experience cybersickness onsets differently than the persons without any disability. Also, the cybersickness reduction techniques (e.g.; SRF) may require some customization for persons with MS. For now, I can say that highly noticeable additional visual cues in the VE do not help the persons with MS to reduce or delay cybersickness onsets rather it requires more attention and processing for them. I believe these findings can work as guidelines for future researchers, VR designers, and VR-based rehabilitation providers/users to mitigate or delay the onsets of cybersickness.