A Technique for Reducing Simulator Side-Effects

This section borrows in part from [80].

Given the hypothesized importance of rest frames to spatial perception, we would expect that a difficulty in selecting a consistent rest frame would have serious consequences. The rest frame construct suggests that motion sickness does not arise from conflicting motion signals per se, but rather from conflicting rest frames deduced from those motion signals. That is, what is crucial is not the full set of motion cues in an environment, but rather how those motion cues are interpreted to influence one's sense of what is and is not stationary. For instance, if one is seated on a bench watching a flock of birds approaching, one has conflicting motion signals (the birds indicate a relative motion, the inertial cues do not). However, one is very unlikely to become motion sick because one's perceptual system is unlikely to interpret the flock of birds as defining the stationary rest frame, and, as such, indicating self-motion. Other visual rest frame cues, from the ground or the sky, are more influential than the flock of birds.

From this point-of-view, the key to avoiding motion sickness is not to remove all conflicting motion cues, but rather to remove those discrepancies which indicate conflicting rest frames. It was argued above that the selected rest frame is heavily influenced by the perceived visual background. Therefore, a foreground/background division of the visual field could be introduced as a means to test the application of the rest frame construct to motion sickness.

A moving visual background (for instance, a wide FOV simulator display) combined with an absence of inertial motion cues is likely to increase motion sickness symptoms. The rest frame indicated by the visual background indicates self-motion, whereas the inertial rest frame cues do not.

This suggests that providing a visual background in agreement with inertial cues may serve to reduce simulator sickness, even when the foreground cues are not in agreement with inertial cues. The application to simulator design is that providing an ``independent visual background'' (IVB) which appears behind the simulator's usual visual ``content-of-interest'' (CI) may provide a simple technique for reducing simulator sickness. The IVB can be made consistent with the inertial rest frame even if the CI (foreground) is not. Two experiments to test this prediction are reported in this dissertation.

Human Interface Technology Lab

Human Interface Technology Lab