Sensation of presence and cybersickness in applications of virtual reality for advanced rehabilitation.
Bottom Line: Virtual stimuli can enlarge sensation of presence, but they sometimes also evoke unpleasant sensation.In order to safely apply augmented and virtual reality for long-term rehabilitation treatment, sensation of presence and cybersickness should be appropriately controlled.In particular, the influence of visual and vestibular stimuli on cardiovascular responses are reported in terms of academic contribution.
Around three years ago, in the special issue on augmented and virtual reality in rehabilitation, the topics of simulator sickness was briefly discussed in relation to vestibular rehabilitation. Simulator sickness with virtual reality applications have also been referred to as visually induced motion sickness or cybersickness. Recently, study on cybersickness has been reported in entertainment, training, game, and medical environment in several journals. Virtual stimuli can enlarge sensation of presence, but they sometimes also evoke unpleasant sensation. In order to safely apply augmented and virtual reality for long-term rehabilitation treatment, sensation of presence and cybersickness should be appropriately controlled. This issue presents the results of five studies conducted to evaluate visually-induced effects and speculate influences of virtual rehabilitation. In particular, the influence of visual and vestibular stimuli on cardiovascular responses are reported in terms of academic contribution.
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Mentions: Sensory and physical assistive devices have long been developed to support impaired functions in patients. Even a powered-suit has recently been developed to strengthen muscle force . Besides, current virtual reality (VR) technology expands not only sensory effects but also physical activities, and the potential effects are expected in rehabilitation engineering . The expecting challenge has been on how to create or promote regular exercises for a variety of individual physical conditions. Figure 1 illustrates recently proposed approaches in advanced rehabilitation according to the type of motor controls (active or passive) and the space of interactions (real or virtual). As shown in Figure 1, active or voluntary physical exercise in the real world increase one's fitness or wellness. However, it needs continuous motivation to keep a habit of regular physical exercise, because people hate sweat and boring repetitive training or exercise. Thus applications to facilitate passive exercises in the real world emerge in the business of health promotion. Mechanically induced motion or electrical stimulations on muscles produce passive exercise. During active exercise, muscles contractions are activated by neural impulses from the brain via the spinal cord to produce voluntary exercise. Reflex, on the other hand, is a reaction to incoming stimuli. Since reflex accompanies with muscle contractions, passive muscle contractions induced by repetitive stimuli have been used to produce passive exercise. Using VR technology, applications can be developed to allow users to experience active or passive exercises in the virtual world without little limitation. Very often, stimuli in VR applications will exceed the normal boundary experienced by users in their daily lives.