Will Simulator-Like Sickness Have Impacts on Training in Virtual Environments?
Authors: Kennedy Robert S. 
Published: January 2012

Motion sickness has long been viewed as an adverse consequence of man's passive transportation in conveyances and vehicles. In all places were worlds of vision, proprioception, or inertial forces are transformed somewhat from past experiences or reality or both. As new forms of vehicular transportation (e.g., aircraft, surface effect ships, spacecraft) have come into use, new forms of motion sickness have appeared as well. Therefore, it is not surprising that when the ability to simulate vehicular self-motion was developed, a form of motion sickness unique to these conditions emerged. It has been referred to as simulator sickness.

Of the flight simulators developed over the past thirty years, the simulators which receive the highest marks for realism from experienced pilots also score high on simulator sickness incidence, although the correlation is not perfect. The express purpose in simulator design has always been to produce the illusion of realism by the use of virtual images. Since simulators are one kind of virtual environment, the question can be posed: “Will simulator-like sickness also occur during training in other virtual environments?”

Several themes and implications are found in one or more studies which relate to virtual environments:

1. It has been suggested in work conducted by the Naval Training Systems Center that the closer one gets to physical fidelity, without actually getting there, the more likely the particular display is to produce simulator sickness. Aside from the fact that all the psychophysical laws which govern the relationship between the richness or fidelity of visual imagery and training effectiveness are not well known, this statement appears approximately true in the case of simulator sickness. However, it has not yet been self-consciously applied in the virtual environment. Some of the papers imply this premise and discuss it further. 2. Locomotor ataxia, interference with higher-order motor control, physiological discomfort, and visual aftereffects or flashbacks occur after simulator flights. These aftereffects may outlast the stimulus for a considerable period of time. While little it known about the perceptual factors in simulation that trigger flashbacks, their duration and their period of retention, their occurrence can, however, be presumed to pose a significant threat to the user's safety immediately following exposure to simulated environments. These aftereffects are likely to be present in some virtual environments, particularly as the exposure duration becomes greater than two hours, the usual upper limit for most flight trainees. 3. Simulator sickness symptomatology can interfere with learning or performance by various means, including distraction due to the presence of physiological disturbance and loss of confidence in a device which creates problems not encountered in the real environment. The most critical problem is that behaviors learned in the virtual environment may not be similar to responses required in the operational environment, potentially resulting in the acquisition of inappropriate perceptual-motor behaviors. 4. The occurrence of simulator sickness can reduce a user's operational readiness by limitations that are enforced on activities on the job. Recreational pursuits may also be limited.

This symposium provides an overview of simulator sickness research and its implications for virtual environment technology. It is composed of four presentations intended to reflect the present state of scientific knowledge and are largely drawn from flight simulation research.