The Impact of Viewing Distance and Proprioceptive Manipulations on a Virtual Reality Based Balance Test.

Our ability to maintain our balance plays a pivotal role in day-to-day activities. This ability is believed to be the result of interactions between several sensory modalities including vision and proprioception. Past research has revealed that different aspects of vision including relative visual motion (i.e., sensed motion of the visual field due to head motion), which can be manipulated by changing the viewing distance between the individual and the predominant visual cues, have an impact on balance. However, only a small number of studies have examined this in the context of virtual reality, and none examined the impact of proprioceptive manipulations for viewing distances greater than 3.5 m. To address this, we conducted an experiment in which 25 healthy adults viewed a dartboard in a virtual gymnasium while standing in narrow stance on firm and compliant surfaces. The dartboard distance varied with three different conditions of 1.5 m, 6 m, and 24 m, including a blacked-out condition. Our results indicate that decreases in relative visual motion, due to an increased viewing distance, yield decreased postural stability - but only with simultaneous proprioceptive disruptions.