NONLINEARITIES OF HUMAN OCULOMOTOR SYSTEM - GAIN

Eye movements of two subjects have been measured while performing various two-dimensional tracking tasks. The stimuli consisted of sums of 3, 4, 7 or 13 sinusoids in each of the horizontal and vertical directions. On the average, the amplitude of the eye-movements decreased with frequency, but within a narrow band the motion increased with frequency. The system also responded preferentially to the highest frequency of a finite number of sinusoids. The behavior of the oculomotor system is non-linear in the sense that it is not possible to predict the response to one class of target motion by linear combination of the responses to other classes of stimuli; nevertheless the tracking eye-movements did not contain harmonics or sum and difference frequencies of the target motion. © 1969.