Sudden visual perturbations induce postural responses in a virtual reality environment

Virtual reality environments can be manipulated allowing controlled visual disturbances. These environmental manipulations (textures, objects, and movements) can affect postural control by creating a sensory mismatch, making it possible to investigate multisensory reweighting. VR integration with motion capture equipment is relatively new; these environmental factors have not received sufficient attention to be employed in postural related research and in VR environment development. Seventeen subjects performed 48 trials of forward and backward translational optic flow in single and double support presented on a head mounted display. Each condition was presented in three different velocities: 3 m/s, 5 m/s and 8 m/s. The effect on center of pressure distance and velocity were analyzed. A repeated measures, counterbalanced experimental design was used. Center of pressure distance travelled increased in the single support condition (p < 0.001). The largest single support postural disturbance was observed in the slowest velocity and longest duration (3 m/s) and the smallest in the fastest velocity shortest duration (8 m/s). A slow optic flow velocity and higher duration of sudden visual translations generates greater disruption to postural control in single support. The velocity and duration of perturbations need to be carefully considered when studying human postural control and the design of VR environments.