any anomaly in the nystagmus or deviation of the eyes in response to stimulation of the vestibular system in which impulses are conveyed from the semicircular canals and the otolithic membrane to the oculomotor nerve; this stimulation may occur by angular acceleration or deceleration or by irrigation of the ear with hot or cold water; normally, this reflex functions to maintain a stable retinal image during head rotation by generating appropriate compensatory eye movements