Visual-based Sensory Motor Learning During Dynamic Balance Tasks Viewed in a Virtual Environment

In this research, we applied a transformation to the normal trajectory used to move and track a visual target in a virtual environment, in order to evaluate adaptation to a visual-based sensory motor transformation. The ability to recalibrate internal to external spatial reference frames is important when changing the relationship between the self and the environment. The virtual task was controlled by the subject's center of foot pressure (COP); the physical COP location is mapped (slaved) to an on-screen cursor (avatar). Target balloons appeared randomly on the screen and the subject was instructed to move the cursor (COP) to intersect the balloon and burst it. When the experimental transformation was applied, the trajectory of the avatar underwent a counter-clockwise rotation of 60deg this required the subjects to update their spatial reference coordinates between the physical COP position and the game avatar. Two parameters were calculated in order to investigate if learning occurred: 1) the displacement angle between the COP trajectory and the direct line path between the starting COP position and target position; and 2) the maximum perpendicular displacement between the COP trajectory and the direct line path to the balloon target. The results showed a decrease in movement error with learning.