Analysis of pursuit tracking eye movements in pilots and nonfliers.

Pursuit tracking eye movements were recorded and analyzed from a group of Air Force pilots and a group of nonflying Air Force members. The tracking performance of the pilots was compared to the performance of the nonfliers. Subjects tracked a small spot of light moving sinusoidally in the horizontal plane at frequencies ranging from 0.2 to 1.0 Hz at a peak-to-peak amplitude of 40 degrees. Maximum target velocities ranged from 25 to 126 degrees/s. An adaptive nonlinear digital filter was used to separate the total tracking response (TTR) into smooth pursuit (SP) and saccadic (SA) components. Frequency domain analysis was used to relate the tracking components to the target movement. There were no statistically significant differences in tracking performance between the pilots and nonfliers. When tracking the 0.2 and 0.4 Hz targets, the TTR consisted principally of SP tracking with SA tracking representing less than 11% of the TTR. As the target velocity increased, the TTR remained adequate but the proportion of SP tracking decreased while the SA tracking increased. Over one-half of the TTR is contributed by the SA system when tracking the 1.0 Hz targets for both the pilot and nonpilot groups.