Non-linear characteristics of visual-vestibular interaction.

Visual-vestibular interaction in the control of eye movement was investigated in six subjects during exposure to a low frequency (0.05 Hz) angular oscillation about the longitudinal axis of the body at four levels of peak head velocity: 30, 60, 90 and 120 degrees/s. For the lower stimulus levels (30 and 60 degrees/s) the degree of suppression of the vestibulo-ocular response was reasonably constant and the nystagmus was never completely suppressed. However, during oscillation at higher velocity levels (90 and 120 degrees/s) the degree of suppression became much less during high velocity periods of the waveform than when the head velocity was low. The changes in suppression may be interpreted as a decrease in gain of visual feedback as a function of increasing image velocity error on the retina.