Variability of eye movement responses to vestibular and visual stimuli. a, b, Variability of eye movement responses to a vestibular stimulus alone (a, 0.5 Hz, 10°/s) and a visual stimulus alone (b, 0.5 Hz, 10°/s) before (Pre) and after (Post) training with a ×0 or ×2 visual–vestibular stimulus. c, Variability of eye movement responses to vestibular (black) or visual (orange) stimuli with a range of peak velocities, plotted as a function of the peak eye velocity elicited, measured in monkey E (circles) and monkey C (diamonds) in the absence of visual–vestibular training.