A, B, Tilt gain for each monkey versus frequency for sinusoidal motion stimuli with the animals tested in the normal state (dark gray icons) and in the BVH state (light gray icons), with error bars representing 95% confidence intervals. C, D, The difference between the normal and ablated states, which approximates the vestibular contribution to tilt perception as a function of frequency. Common testing frequencies for the two monkeys were 0.1 and 0.2 Hz (bold, x-axis).