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Motion sickness is common in virtual environments. The risk of motion sickness varies widely between individuals and across situations. The subjective experience of motion sickness often is preceded by distinctive patterns of movement in the control of head and body posture. Previous research has documented reliable sex differences in the kinematics of postural activity, as well as reliable differences in postural activity between participants who were in control of a virtual vehicle and participants who were not. We asked whether postural precursors of motion sickness would simultaneously be influenced by individual and situational factors. We analyzed movement of the head and torso while seated participants were exposed to a driving video game presented through a head-mounted display. Half of the participants were women, and half were men. Using a yoked-control design, half of the participants controlled the virtual vehicle ( Drivers ), whereas half watched previously recorded vehicle trajectories ( Passengers ). The maximum exposure duration was 15 min, but participants were instructed to discontinue participation immediately if they experienced any symptoms of motion sickness, however mild. We analyzed movement kinematics not only in terms of sex and vehicle control but also in terms of participants who did or did not report motion sickness. Movement differed between Drivers and Passengers, in terms of both the spatial magnitude and multifractality of movement. The spatial magnitude of movement was simultaneously influenced by sex (men vs. women) and vehicle control (Drivers vs. Passengers). In addition, in statistically significant interactions, we identified postural precursors of motion sickness that differed between Drivers and Passengers and, separately, between Drivers and Passengers as a function of sex. The results are consistent with a prediction of the postural instability theory of motion sickness etiology and shed new light on the multifactorial origins of postural precursors of motion sickness in virtual environments. 

Previous research has shown that individuals behave differently in certain virtual reality tasks. The effect of VR on human posture and stability is an important factor that can influence the future applications of VR devices. This current study seeks to investigate how a person’s postural stability differs between VR and normal environment while attempting to replicate the influence of target distance on sway. Ten healthy subjects were tested in both environments with targets varying in distance. The results found a significant difference in postural stability for normal anatomical stance tasks between VR and normal environments. 

The auspicious future of VR could be thwarted by cybersickness. A factor known to influence susceptibility is sex, with females often experiencing higher incidences. A mitigation strategy is to identify individuals who are more sensitive to cybersickness, such that interventions can be implemented before the onset of subjective symptoms. Such an approach could use predictive models that compare a user’s online kinematic body sway and physiological characteristics to data from individuals that reported cybersickness. If such predictive models can be developed, then one approach is altering the virtual environment (VE) based on this real-time data. The benefit of adjusting the VE is that it permits a susceptible individual to use the VR device with a reduction in adverse symptoms. One way to alter the VE is by manipulating optic flow, which can be described as the perceived visual motion of objects that are generated through an observer’s movements. Optic flow can be increased by increasing the level of details in the VE. That is to say, visual displays that contain a lot of details often give rise to stronger subjective sensations of movement. Thus, if the level of details in the VE is reduced, then this may reduce cybersickness reports. 

Proprioception or body awareness is an essential sense that aids in the neural control of movement. Proprioceptive impairments are commonly found in people with neurological conditions such as stroke and Parkinson’s disease. Such impairments are known to impact the patient’s quality of life. Robot-aided proprioceptive training has been proposed and tested to improve sensorimotor performance. However, such robot-aided exercises are implemented similar to many physical rehabilitation exercises, requiring task-specific and repetitive movements from patients. Monotonous nature of such repetitive exercises can result in reduced patient motivation, thereby, impacting treatment adherence and therapy gains. Gamification of exercises can make physical rehabilitation more engaging and rewarding. In this work, we discuss our ongoing efforts to develop a game that can accompany a robot-aided wrist proprioceptive training exercise.