Determines the adequacy of reflex compensatory eye-movements for maintaining visual fixation in the presence of bodily movements of rotation. The apparatus and technique used were modifications of those previously described. Every environmental rotation was subdivided into comparable periods of visual pursuit nystagmus and periods of pure vestibular nystagmus. The former were registered whenever S, with one eye open, looked at his environment through the opening of a diaphragm. Periods of pure reflex compensation supervened when the diaphragm was closed so that the S saw nothing of his environment. Mirrors were used to make the environment appear moving in (i) natural direction (ii) opposite to the natural direction or (iii) not moving at all. The results revealed that with the environment moving in the normal direction, the eye-movements of vestibular origin (i.e., reflex compensatory eye-movements) may be an adequate compensation at the beginning of rotation, but as rotation continued, the vestibular deviation gradually died out to the complete inadequacy of a resting eye. With reversed motion of the visual field, vestibular deviations, as well as deviations of visual pursuit, showed irregularities, hesitations, and reversals. As the speed of rotation increased, marked rivalry of control between vestibular and visual processes was apparent, and both forms of control were impaired. Concluded that the vestibule is not an exact regulator of action. It initiates, with low reaction latency, a reflex compensation of the eyes, whose adequacy depends on the subsequent control of vision. From Psych Bulletin 21:01:00032. (PsycINFO Database Record (c) 2006 APA, all rights reserved)