Efficacy of Galvanic Vestibular Stimulation as a Display Modality Dissociated from Self-Orientation.

Objective: We propose and assess galvanic vestibular stimulation (GVS) as a novel means to provide information dissociated from self-orientation.

Background: In modern user interfaces, visual and auditory modalities dominate information transfer so much that these "processing channels" become overloaded with information. Fortunately, the brain is capable of processing separate sensory sources in parallel enabling alternative display modalities to inform operators more effectively and without increasing cognitive strain. To date, the vestibular system, normally responsible for sensing self-orientation and helping with balance, has not been considered as a display modality.

Method: Bilateral GVS was provided at 0.6 mA for 1-second intervals with moderately high-frequency sinusoidal waveforms, designed to not elicit sensations of self-motion. We assessed subjects' ability to differentiate between two cues of different frequencies.

Results: We found subjects were able to reliably distinguish between cues with an average just-noticeable difference threshold of only ±12 Hz (range across subjects: 5.4-19.6 Hz) relative to a pedestal cue of 50 Hz. Further, we found the GVS sensory modality to be robust to various environments: walking, standing, sitting, passive motion, and loud background noise. Finally, the application of the GVS cues did not have significant destabilizing effects when standing or walking.

Conclusion: These results show that GVS may be an effective alternative display modality, using varying frequency to encode information. It is robust to various operational environments and non-destabilizing.

Application: A fully functional display can convey information to operators of vehicles and other machinery as well as high-performance operators like astronauts and soldiers.