Ability to modify sensory and motor systems in response to changing task and environmental demands. Also referred to as Equilibrium and Righting Reactions. Equilibrium Reactions are compensatory movements of the body parts that serve to maintain the center of gravity over the base of support, when either the center of gravity or support surface is displaced. Righting Reactions are use to attain or regain such postures. These reactions are related primarily to visual and vestibular-proprioceptive functions. Deficits in vestibular proprioceptive functioning are most apparent when balance deficits occur under conditions where vision is occluded.