Virtual Reality and Assistive Technologies: A Survey <s> VI. DRAWBACKS IN VR-BASED REHABILITATION <s> A common measure of the quality or effectiveness of a virtual environment (VE) is the mount of presence it evokes in users. Presence is often defined as the sense of being there in a VE. There has been much debate about the best way to measure presence, and presence researchers need, and have sought, a measure that is reliable, valid, sensitive, and objective.We hypothesized that to the degree that a VE seems real, it would evoke physiological responses similar to those evoked by the corresponding real environment, and that greater presence would evoke a greater response. To examine this, we conducted three experiments, the results of which support the use of physiological reaction as a reliable, valid, sensitive, and objective presence measure. The experiments compared participants' physiological reactions to a non-threatening virtual room and their reactions to a stressful virtual height situation. We found that change in heart rate satisfied our requirements for a measure of presence, change in skin conductance did to a lesser extent, and that change in skin temperature did not. Moreover, the results showed that inclusion of a passive haptic element in the VE significantly increased presence and that for presence evoked: 30FPS > 20FPS > 15FPS. <s> BIB001 </s> Virtual Reality and Assistive Technologies: A Survey <s> VI. DRAWBACKS IN VR-BASED REHABILITATION <s> We present a wireless virtual reality system and a prototype full body Tai Chi training application. Our primary contribution is the creation of a virtual reality system that tracks the full body in a working volume of 4 meters by 5 meters by 2.3 meters high to produce an animated representation of the user with 42 degrees of freedom. This - combined with a lightweight (<3 pounds) belt-worn video receiver and head-mounted display - provides a wide area, untethered virtual environment that allows exploration of new application areas. Our secondary contribution is our attempt to show that user interface techniques made possible by such a system can improve training for a full body motor task. We tested several immersive techniques, such as providing multiple copies of a teacher's body positioned around the student and allowing the student to superimpose his body directly over the virtual teacher None of these techniques proved significantly better than mimicking traditional Tai Chi instruction, where we provided one virtual teacher directly in front of the student. We consider the implications of these findings for future motion training tasks. <s> BIB002 </s> Virtual Reality and Assistive Technologies: A Survey <s> VI. DRAWBACKS IN VR-BASED REHABILITATION <s> During self-motion, the world normally appears stationary. In part, this may be due to reductions in visual motion signals during self-motion. In 8 experiments, the authors used magnitude estimation to characterize changes in visual speed perception as a result of biomechanical self-motion alone (treadmill walking), physical translation alone (passive transport), and both biomechanical self-motion and physical translation together (walking). Their results show that each factor alone produces subtractive reductions in visual speed but that subtraction is greatest with both factors together, approximating the sum of the 2 separately. The similarity of results for biomechanical and passive self-motion support H. B. Barlow's (1990) inhibition theory of sensory correlation as a mechanism for implementing H. Wallach's (1987) compensation for self-motion. <s> BIB003 </s> Virtual Reality and Assistive Technologies: A Survey <s> VI. DRAWBACKS IN VR-BASED REHABILITATION <s> Previous research suggests that postural sway in standing increases in virtual reality (VR) environments. This study was conducted to examine whether gait instability is prevalent when people walk in a VR environment. Ten healthy adults participated in the study. Subjects walked on a treadmill in a VR environment and a non-VR environment at each of three walking speeds: 0.9, 1.1, and 1.3 m/s. In the VR environment, an endless corridor with colored vertical stripes comprising the walls was projected onto a hemispherical screen placed in front of the treadmill. The speed of the moving corridor image was matched to the speed of the treadmill to create the illusion that subjects were walking through the endless corridor. Spatiotemporal data during gait were collected with an instrumented treadmill housing two piezoelectric force platforms. Gait parameters reflective of gait instability (stride length, step width, variability in stride velocity, and variability in step width) were compared between the VR and non-VR environments. Subjects walked in the VR environment with reduced stride lengths (p = 0.001), increased step widths (p = 0.001), and with increased variability in stride velocity (p < 0.001) and step width (p = 0.002). The gait deviations suggest that walking in a VR environment may induce gait instability in healthy subjects. <s> BIB004 </s> Virtual Reality and Assistive Technologies: A Survey <s> VI. DRAWBACKS IN VR-BASED REHABILITATION <s> AbstractFull-body motion tracking data was collected for six subjects during free walking. Each participantwas asked to walk to a previously seen target under four experimental conditions: eyes closed withinthe real world, eyes closed wearing a head-mounted display (HMD), eyes open in the real world, andeyes open wearing a HMD. We report three gait parameters for each of these four conditions: stridelength, walking velocity, and head-trunk angle. This data reveals that these gait parameters within aHMD virtual environment (VE) are diﬀerent than those in the real world. A person wearing a HMDand backpack walks slower, and takes a shorter stride length than they do in a comparable real worldcondition. In addition, head-trunk angle while walking to a target on the ground plane is lowest whenwalking with eyes open in a HMD VE.Categories and Subject Descriptors (according to ACM CCS) : I.3.7 [Computer Graphics]: VirtualReality1. IntroductionTreadmill virtual environments (VEs) are alreadyproving useful for investigating locomotor behavior[MTR <s> BIB005 </s> Virtual Reality and Assistive Technologies: A Survey <s> VI. DRAWBACKS IN VR-BASED REHABILITATION <s> AIM ::: To evaluate the effects of ''Playstation EyeToy Games'' on upper extremity motor recovery and upper extremity-related motor functioning of patients with subacute stroke. ::: ::: ::: METHODS ::: The authors designed a randomized, controlled, assessor-blinded, 4-week trial, with follow-up at 3 months. A total of 20 hemiparetic inpatients (mean age 61.1 years), all within 12 months post-stroke, received 30 minutes of treatment with ''Playstation EyeToy Games'' per day, consisting of flexion and extension of the paretic shoulder, elbow and wrist as well as abduction of the paretic shoulder or placebo therapy (watching the games for the same duration without physical involvement into the games) in addition to conventional program, 5 days a week, 2-5 hours/day for 4 weeks. Brunnstrom's staging and self-care sub-items of the functional independence measure (FIM) were performed at 0 month (baseline), 4 weeks (post-treatment), and 3 months (follow-up) after the treatment. ::: ::: ::: RESULTS ::: The mean change score (95% confidence interval) of the FIM self-care score (5.5 [2.9-8.0] vs 1.8 [0.1-3.7], P=0.018) showed significantly more improvement in the EyeToy group compared to the control group. No significant differences were found between the groups for the Brunnstrom stages for hand and upper extremity. ::: ::: ::: CONCLUSION ::: ''Playstation EyeToy Games'' combined with a conventional stroke rehabilitation program have a potential to enhance upper extremity-related motor functioning in subacute stroke patients. <s> BIB006 </s> Virtual Reality and Assistive Technologies: A Survey <s> VI. DRAWBACKS IN VR-BASED REHABILITATION <s> The multimodal, 3D-graphical communication platforms known as virtual worlds have their historical roots in multi-user domains/dungeons (MUDs) and virtual reality (VR). Given the extensive research on these technologies and the novelty of virtual worlds as a topic of study in information systems (IS), it behooves us to learn from the concepts, theories and insights generated primarily by other disciplines that have focused on these technologies. Because neither MUDs nor VR have significant organizational application, thus locating them outside of the IS discipline’s purview, very little of this literature has found its way into IS research thus far. This article reviews the extant literature on virtual environments and seeks to make its insights accessible to IS research on virtual worlds. In particular, this will focus on concepts, theories and insights regarding embodiment and presence, which are afforded by the avatar, a distinguishing technological artifact of virtual worlds. <s> BIB007 </s> Virtual Reality and Assistive Technologies: A Survey <s> VI. DRAWBACKS IN VR-BASED REHABILITATION <s> In the past decade, several arm rehabilitation robots have been developed to assist neurological patients during therapy. Early devices were limited in their number of degrees of freedom and range of motion, whereas newer robots such as the ARMin robot can support the entire arm. Often, these devices are combined with virtual environments to integrate motivating game-like scenarios. Several studies have shown a positive effect of game-playing on therapy outcome by increasing motivation. In addition, we assume that practicing highly functional movements can further enhance therapy outcome by facilitating the transfer of motor abilities acquired in therapy to daily life. Therefore, we present a rehabilitation system that enables the training of activities of daily living (ADL) with the support of an assistive robot. Important ADL tasks have been identified and implemented in a virtual environment. A patient-cooperative control strategy with adaptable freedom in timing and space was developed to assist the patient during the task. The technical feasibility and usability of the system was evaluated with seven healthy subjects and three chronic stroke patients. <s> BIB008 </s> Virtual Reality and Assistive Technologies: A Survey <s> VI. DRAWBACKS IN VR-BASED REHABILITATION <s> One of the major challenges in designing exercise games (exergames) is maintaining engagement and motivation over time. Previous research has shown that games can increase the motivation exercise. However, these games are typically developed with limited set of specific exercises in mind, which limits genre choices, and potentially long term motivation. To address this critical issue, we are interested in employing any exercise as an interface to common, existing, sedentary games, such as a car racing game. Specifically, in this paper, we aim to take initial steps toward this goal. As a proof of concept, we developed 2 exercised based interfaces for a car racing game - a game genre minimally used for exergames. We present the evaluation of our novel exercise interfaces to the racing game, and offer general guidelines for converting common classes of sedentary games to exergames. <s> BIB009
A VE can negatively affect users' gait, physiological response, and presence. A delay between a users actions and consequent changes in the virtual world can destroy the sense of engagement and can lead to physical disorientation and nausea  BIB003 . The lack of humanness of virtual characters and spontaneity in interaction can distract the level of immersion of the subjects too. Some participants stated that the VE seems unnatural as they found it challenging to coordinate the real movement to a virtual grasp of virtual objects, even with assistance of the devices BIB008 . Additionally, virtual devices like HMDs can be a source of encumbrance that would likely hinder the motor response of patients with neurological deficits. Sometimes users wearing an HMD could see a part of the real world due to a limited vertical field of view and their attention was distracted while walking in a VE  . Sometimes subjects reported difficulty in exacting a performance even with a virtual trainer with accurate body movement superimposed on their own virtual avatars BIB002 . They also reported to feel more fatigued in a VR-enhanced environment BIB009 . These findings may be attributed to the fact that a virtual body in a VE could increase the presence of focusing on visual senses and users become more conservative and cautious while exacting the performance BIB007  . Sometimes patients were found to be frustrated while playing a particular game if the game does not involve sufficient amount of motivation or engagement. It was also reported that participants seemed to be more interested in visually exploring the environment rather than inspecting the avatars for posture control (Guo, Samaraweera, and Quarles 2013). In some experimental results, the percentage of time in good form was found to be lower in games compared with the real world (Guo and Quarles 2013). Thus visual cues and avatars can negatively affect gait in velocity, stride length, and step length. Several studies resulted in contradictory remarks as addition of a VR environment does not normalize the comfortable walking speed, but lowers the stride length with increased step width BIB004 . Mohler et al. found that a person wearing an HMD and backpack walks slower, and takes a shorter stride length in a VE than they do in a comparable real world condition BIB005 ). However, Phillips et al. found that a person takes significantly shorter strides in a stressful VE compared to a controlled VE  ). Different evaluation methods regarding users performance improvement like Functional Independence Measure (FIM) focus on the performance of the individual on a specific activity. FIM does not consider whether a particular VE-based rehabilitation has contributed to the development of compensatory self-care strategies by the non-paretic side over time or the paretic limb BIB006 . A very few research works were found to consider this issue in performance evaluation ). Parsons et al. commented that some autistic children failed to demonstrate social use of the lessons learnt in a VE; participants learn how to use VE but not where to use it (Parsons, Leonard, and Mitchell 2006). The reason was mainly attributed to the paucity of social contact available to these participants. For better outcome, not only the cognitive play in VE but also broader exposure to social environments and wider social interaction would be necessary. Different VR-enhanced systems can affect subjects in different ways. Participants in the low latency condition had a higher self-reported sense of presence BIB001 . Though participants were found to walk more slowly in VEs, they commented that the avatar made walking in the VE more realistic (Samaraweera, Guo, and Quarles 2013). Research must also take into account individual differences because each persons ability to perform a particular task varies from others. VEs, games, or devices that work for some individuals might not work for others. This variance can greatly impact the level of improvement of each person undergoing rehabilitation. Thus a more customized device or virtual task help the participants interact better (Broeren, Rydmark, and Sunnerhagen 2004).