Visual counteraction on nauseogenic and disorienting effects of some whole-body motions: a proposed mechanism.

It has been indicated that the nauseogenic and disorienting effects of several kinds of provocative motion stimuli can be ameliorated by visual reference to the Earth. The purpose of the present experiment is to investigate a hypothesis concerning the mechanism of this beneficial effect. The results demonstrate that the aftereffects of large-field optokinetic stimulation can nullify the nauseogenic and disorienting effects of Coriolis cross-coupled vestibular stimuli. It is hypothesized that large-field optokinetic stimulation in a particular head plane modifies activity in the vestibular nuclei as though the semicircular canals in that plane had been stimulated. A previous study illustrated that such semicircular canal stimulation would completely nullify the disturbing and disorienting effects of Coriolis cross-coupled stimulation according to theoretical expectations. The results provide inferential support for the hypothesis and suggest that predictability of disorientation and nauseogenic disturbance is reasonably well handled by current theory when the conditions of motion are fairly well specified.