Underwater virtual reality for spatial orientation research.

Abstract

Spatial orientation is the sense of self-motion and orientation relative to the environment. Perception of spatial orientation depends most strongly on information from the visual and vestibular systems, but somatosensory and proprioceptive modalities also contribute. Like the vestibular system, these modalities transduce linear and angular accelerations acting on the body which allow reconstructing how the body is supported and moved. Because these systems typically respond to the same stimuli, methods are needed to distinguish how perception is driven by vestibular versus somatosensory and proprioceptive modalities. We therefore developed a system for conducting psychophysical experiments underwater, where somatosensory and proprioceptive cues to body orientation are rendered largely uninformative. The system consists of a full-face dive mask that has been modified to accommodate a smartphone and lenses, turning it into an underwater head-mounted display (HMD). The phone is connected to a wired, waterproofed Xbox controller for input. To demonstrate usability of the system, we conducted an experiment in which participants were trained to use jetpack locomotion to navigate a series of gates in the simulated zero-gravity environment outside the international space station. Simulated locomotion was visual only. Safety and neutral buoyancy of the participants was constantly monitored by a companion diver. Nine participants (3F) completed the experiment, both while seated in a chair above water (familiarization), and while neutrally buoyant underwater. Participants also completed simulator sickness questionnaires before and after each of these periods. Participants showed a significant decrease in time taken to complete the virtual locomotion task while underwater. Simulator sickness reports did not differ significantly between the underwater and familiarization phases. We discuss strengths and limitations of the underwater VR system as well as future research that could be facilitated by this technology.

Acknowledgement: Research was supported by the Nevada-NASA Space Grant Consortium, under NASA NNX15AI02H.