Application of electrovestibulography (EVestG) coupled with virtual reality to investigate visual-vestibular interaction: An exploratory human study

The integration of visual and vestibular information is an example of multisensory processing commonly applied to our daily life. The undeniable role of visual inputs in compensation, restoration, and adaptation for vestibular deficiency has been addressed in several studies. However, current literature fails to objectively measure vestibular responses following a targeted visual stimulus. In the studies of this thesis, using Electrovestibulography (EVestG), we measured participants’ vestibular activity from the ear canals in response to targeted visual stimuli, developed in immersive virtual reality (VR) environments, delivered through a head-mounted display (HMD), quantitatively and non-invasively. This dissertation consists of four sub-studies: 1. Quantifying the difference between physically (applied via a hydraulic chair)- and visually (replicas of the physical tilts designed in a VR environment)-induced vestibular responses; 2. Investigating vestibular responses to the combined and individual effects of intensity and hue of three monochromatic colored-light stimuli (blue, green, red); 3. Investigating changes in the vestibular activity when exposed to a horizontal pursuit and saccadic eye movements; and 4. Investigating vestibular responses to the visually-evoked sensation of body movement (Vection) utilizing a VR roller-coaster. Overall from the four sub-studies mentioned above, we conclude that different visual stimuli can produce a measurably different vestibular response (measured by EVestG) depending on the VR environments’ characteristics (object motion, color, etc.). As long as the applied visual stimuli do not induce a self-motion sensation, the vestibular response is generally inhibitory (sub-studies 2 and 3). Upon feeling a self-motion sensation, the vestibular response may become an excitatory response (sub-study 4). To better understand the implications of these results, future studies should address the effect of other factors in the field of view