Perceptual Validation of Nonlinear Postural Predictors of Visually Induced Motion Sickness

Abstract

Virtual reality (VR) technology has become increasingly prevalent in our society and has been used for a myriad of applications ranging from psychotherapy to training members of the military. However, one issue that arises from the use of VR is motion sickness, thus making predictors and indicators of motion sickness desirable. To date, a number of indicators of motion sickness have been derived based on nonlinear characteristics of human motion recorded using motion capture systems. While it is known that nonlinear measures can be used to predict motion sickness, it is not known whether people are perceptually sensitive to these particular nonlinear parameters. The aims of this study included establishing whether individuals consistently sort phase plots of sick and well individuals’ postural motion without being explicitly told to do so; determining what nonlinear movement parameters could be used to represent these judgments; and assessing the stability of nonlinear measures found to be successful at predicting motion sickness by Smart et al. (2014) . Through two methods of analysis (perceptual and quantitative), this research demonstrated that participants can indeed sort the graphic depictions of sick and well participants’ postural motion and seem to be perceptually sensitive to nonlinear parameters (normalized path length, path length, elliptical area) that are known to be predictive of motion sickness.

Using Nonlinear Kinematic Parameters as a Means of Predicting Motion Sickness in Real-Time in Virtual Environments

“…It was found that the well participants that were incorrectly flagged as sick tended to be flagged only in their later trials. This is consistent with previous work that demonstrates that postural instability emerges over time even in well participants (Koslucher, et al, 2016; Smart et al, 2002; 2007; Teaford et al, 2020; Villard et al, 2008). See Figure 3 for a graphic depicting the mean slope values (i.e.…”

“…Ideally, a motion sickness prediction algorithm for the consumer setting would utilize data already being collected by the virtual device; thus, negating the need for additional specialized equipment as well as minimizing the additional computational load on the computer. Specifically, many current virtual devices track motion/position of the user that we argue could be utilized to make predictions about behavioral/physiological states (Teaford et al, 2020).…”

“…The discovery of these patterns is intriguing from a prediction standpoint because it suggests a particular and potentially programmable means of determining outcomes. In fact, a recent analysis by Teaford et al (2020) demonstrated that not only were these measures predictive when tested with archival data (Smart et al, 2002; Stoffregen & Smart, 1998) using a discriminant analysis (79% accurate comparable to Smart et al, 2002; 2007) but also appeared to be indices that are perceptually detectable as well (sorting of postural movement plots into categories mapped onto differences in nonlinear indices). These measures are also implicated in participants’ differential behavioral responses to presentation of posture-based optical flow (Cook IV et al, 2018).…”

The Influence of Walking Height and Width on the Gait

“…Simeonov used virtual reality (VR) technology to simulate walking on a roof plank and observed the effect of height on the lateral angular velocities of the trunk and rearfoot [ 28 ]. Motion sickness caused by VR technology could be confused with the effect of path height and width on walking [ 29 , 30 ]. The effects of narrow and wide path width on the trunk and joint kinematics have been compared [ 27 , 28 , 31 ].…”

Motion sickness: current concepts and management

“…According to the sensory conflict theory, a mismatch between the information delivered by the visual, vestibular, and/or somatosensory system that is not in accordance with the movement predicted by a cortical, internal model is the primary cause for motion sickness [2 ▪▪ ]. In contrast, the postural instability theory claims that changes in one's ability to control posture and balance are the primary cause for motion sickness, preceding the onset of symptoms [9,10]. The latter theory has generated controversy as well controlled studies failed to find a relationship between postural control and motion sickness [11 ▪ ].…”