Abstract
Vehicle simulators and other virtual environments often lead to vection, a form of self-motion perception that can significantly enhance the realism of simulator displays. Unfortunately, a form of motion sickness known as simulator sickness often accompanies vection. What is the relationship between vection and simulator sickness? A fuller understanding of vection may offer answers. Vection can increase or decrease in magnitude, change direction, or vary in perceived velocity (changing vection), or vection can be a steady perceptual experience (steady vection). It was hypothesized that changing vection is the main causal agent of simulator sickness. The underlying logic: the vestibular system responds only to changes in tilt, velocity, and heading. If a participant's head is immobilized and vection is steady, visual and vestibular sensory inputs should be the same as if actual self-motion were occurring. Under such conditions of actual self-motion, sickness is rare. Method: experiments were conducted using optical flow patterns on a CRT computer monitor and in optokinetic drums. The direction and velocity of the patterns were manipulated. Vection was measured using a computer interfaced slide control that participants were asked to push with increasing force to indicate that vection magnitude was increasing. Simulator sickness was measured using the Simulator Sickness Questionnaire designed by Kennedy and colleagues (1993). Results: stimuli that changed direction and/or velocity yielded significantly more simulator sickness. Conclusion: changing vection is the main cause of simulator sickness perhaps because it is accompanied by a higher degree of visual/vestibular disparity compared to steady vection.
Supported by NSF Grant BCS-0447785