Abstract
Characteristics of smooth pursuit eye movements elicited by auditory stimuli are studied in comparison with those by visual stimuli. The amplitude of response is smaller and the delay time is longer for auditory stimuli than for visual stimuli. Frequency characteristics show similar low-pass shapes in both cases.
The error of direction or motion between a target and the line of sight is detected through the retina for the visual stimulus and is generally considered to be minimized by the feedback control in the eye movement system. To obtain unity gain in the low-frequency region in such a negative feedback control system, the gain of the feedforward path of the system should be extremely high.
For auditory stimuli, feedback control does not take place since the error detector does not exist, so the frequency characteristics are measured as those of the feedforward path of the smooth pursuit system. The frequency characteristics show similar low-pass shapes for both auditory and visual stimuli suggesting that the smooth pursuit system works as a feedforward system responding to a perceived motion in both cases and is not a generally conjectured feedback control system.
