Postural movements induced by rotations of visual scenes.

The effect of visual information processing of a rotating visual scene on postural responses of a standing subject was studied. Rotation of a scene induced postural sway movements involving rotations in the ankle joint. For modulation frequencies of rotation below 0.3 Hz, a clear correlation was found between the visual stimulus and the postural movements in the lateral direction. The amplitude of postural movements appeared to be independent of the angular velocity of the rotation of the scene if the angular velocity exceeded 5 deg/sec for sinusoidally modulated rotations or 10 deg/sec (rms values) for randomly modulated rotations. To facilitate distinction between the contributions from visual information processing of the incoming visual stimuli and from the motor system, a model is presented that explains some aspects of visuo-motor interaction.