Abstract
Previous studies examined the influence of visual reference (VR) upon postural and ambulatory abilities in dynamic motion environments. Consistent with previous research on visual influence on postural abilities in static environments, this study found significantly greater levels of postural instability, in conditions of reduced VR in dynamic motion environments. These results suggested that visual input to postural stability (PS), such as stable VR of the static environment within which the motion occurs, may have important implications to the safety of individuals working in enclosed vehicular conveyances. To determine if conditions of reduced VR, previously found to compromise PS, also yielded compromised feelings of well-being [increased motion sickness (MS)], subjects were tested on a motion platform driven by a simulated ship-motion profile. PS measures included force plate recordings before and after motion exposure, and the frequency of motion-induced interruptions (MIIs) during exposure. MS measures included tolerance to the motion environment (tolerance time), as well as MS symptom checklists (subjects rated 25 common symptoms of discomfort) completed before, after, and every three minutes during exposure. In the 1st condition, subjects were allowed to see the walls and ceiling of the test cubicle that housed the motion platform (+VR). In the 2nd condition, curtains attached to the motion platform precluded this view (−VR). Significantly more MIIs were found in -VR condition, consistent with previous studies. Significantly more symptoms of confusion and dry mouth, and fewer symptoms of boredom, sighing and yawning were reported in -VR condition. However, these analyses failed to reveal significant differences in MS measures of tolerance or nausea. These results suggest that visual reference may be of greater importance to PS than to MS. The attention required for ambulation in the challenging -VR conditions within dynamic motion environments, may prevail over any attention to somatic complaints of MS.
John Alt and Warren Belazer for their technical assistance.