Abstract
Purpose :
To determine whether visually induced postural response change when subjects are exposed to moving stimuli, displayed within HMD or projected on a large screen.
Methods :
Twenty young adults (aged between 20 and 30) participated in the experiment. They stood, barefoot and arms along the body, in front of a projection screen. Optical motion sensors, located on a helmet, and 6 IR cameras (Optotrak system) were used to track and register head movements during trials. The stimulus displayed on the screen was a black and white checkerboard with an empty grey area (5° of visual angle) in front of the subject’s eyes. The peripheral checkerboard could be either static or in motion: 2Hz periodic translation in Antero-Posterior and Medio-Lateral directions. The same visual environment was also displayed within a HMD (Oculus Rift). We calculated the Velocity Root Mean Square (VRMS) of head movements based on the signal provided by the optical sensors. VRMS represented a measure of postural instability induced by the various visual conditions. Motion sickness symptoms were also measured with Simulator Sickness Questionnaires (Kennedy et al., Int J Aviat Psychol 1993; 3:203-20).
Results :
Results showed that the postural instability induced by the visual peripheral motion was more important with the screen projection than with the HMD. SSQ scores also showed that subjects were more uncomfortable following HMD sessions compared to screen projection.
Conclusions :
Previous studies showed that adding a load on the head changes the postural behavior (Knight, Barber, Aviat Space Environ Med 2004; 75:123-31). Therefore, in our experiment, the weight of the HMD may be an explanation for the change in visually induced postural responses.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.