Influence of abnormal postural and sensory conditions on human sensorimotor localization.

A wide range of experiments exposing subjects to unusual postural, sensory, and gravitational conditions have been discussed. In general, regardless of the nature of the experimental intervention, changes in sensory localization and sensorimotor coordination resulted. After prolonged exposure to the abnormal stimulus situation, sensory localization as well as sensorimotor coordination showed evidence of compensation, with performance returning toward normal. Our characterization and understanding of these experimental situations has only begun. Similar principles appear, however, to underlie many of these studies. Changes in interpreted posture induced by angular and linear acceleration are accompanied by changes in visual and auditory localization of comparable size. Rearrangement of the visual array by prism spectacles causes errors in sensorimotor coordination that are later eliminated by postural adjustments. Thus, in general, exposure to visual orientation, results in errors insensory localization; exposure to these abnormal states leads to compensatory alterations in postural and sensory mechanisms by a systematic modification of their interrelationship.