An introduction of a direct vestibular display into a virtual environment

The US Air Force Armstrong Synthesized Immersion Research Environment Facility is currently investigating the development and potential application of direct vestibular displays. The Electrical Vestibular Stimulus (EVS) technology described in the paper uses electrodes located behind the ears to deliver a low level electrical current in the vicinity of the eighth cranial nerve of the central nervous system to produce a compelling sensation of roll motion about the body's fore-aft axis. In the study described, subjects experienced the EVS display while simultaneously observing a large field of view visual display which depicted curvilinear motion through a tunnel. Both EVS and visual displays were driven in a sinusoidal fashion at various phase relationships relative to one another. After observing the two displays, subjects were asked to rate various aspects of quality and magnitude of self motion. Results revealed that the fidelity of the motion experience depended upon the phase relationship between the EVS and visual displays. Results also indicated that when an appropriate phase relationship was used, the vestibular display significantly improved the fidelity of the motion experience when compared to a visual only display.