Subtle velocity dependent postural reorganization in the virtual environment

Virtual environments are becoming popular as a tool for clinical assessment and intervention, but it is not clear whether motor behaviors within such environments are consistent and reliable. We have explored how exposure to a single velocity of optic flow is altered when also exposed to a faster or slower velocity in 23 young healthy adults during quiet standing. Two groups experienced pitch up and pitch down motion of the visual scene at 30 deg/s and either a faster visual scene at 45 deg/s and or a slower visual scene at 15 deg/s. No significant differences in postural sway to 30 deg/s were observed across groups in either the AP direction or the ML direction. This suggests that the postural behavior is velocity dependent and not reorganized as a result of concurrent exposure to differing visual velocities.