Changes in the direction of vestibulomotor response in the course of adaptation to protracted static head turning in man

Vestibulomotor response during the course of adaptation to prolonged (10 min) static head turning to the furthest limit was investigated in healthy subjects standing upright with the eyes closed. The head was either actively or passively maintained in this position. The sensation of a decline in the angle of head turning was experienced during adaptation to the position by five of the 12 subjects tested. Error in appreciating this angle ranged up to 70–80°. Matching changes occurred in the direction of vestibulomotor response to electrical stimulation of the vestibular apparatus. When true and perceived head position conflict, direction of vestibulomotor response thus matches spatial perception rather than actual orientation of the head.