Influence of visually induced self-motion on postural stability

Conclusion. Our results indicate that the illusion of self-motion is a significant factor leading to spatial disorientation. Objective. Under normal circumstances, self-motion is perceived in response to motion of the head and body. However, under certain conditions, such as virtual reality environments, visually induced self-motion can be perceived even though the subject is not actually moving, a phenomenon known as "vection". The aim of this study was to examine the possible influence of illusory self-rotation (circular vection) on postural adjustments. Material and methods. The subjects were 10 young females with no history of ocular or vestibular disease. Video-motion analysis was applied to measure postural movements during vertical optokinetic stimulation. Results. For most subjects, movement of the visual surroundings induced head and body displacements in the same direction as that of the visual stimulus, regardless of the onset of self-motion perception. However, there was a significant increase in postural instability after the subjects began to perceive false self-motion in the opposite direction to that of the visual stimulus.