Abstract
Abstract: :
Purpose: Smooth pursuit eye movements are important in operating moving vehicles, where they might be used for instrument scanning or to track vehicles merging into the operator's path. The purpose of this experiment was to determine whether smooth pursuit tracking could be influenced by a complex (flight simulator) background. Method: 5 subjects participated in two sessions. In the first session, subjects tracked a pseudo-random two-dimensional laser target (distance = 3.4m). The target was the sum of 6 sinusoids (0.24 to 1.25Hz) in the vertical and the sum of 5 sinusoids in the horizontal (0.37 to 1.25Hz). Maximum amplitudes were 11 deg (vertical) and 15 deg (horizontal). In one trial subjects tracked the target against a dark background (dark) and in a second trial subjects tracked the target against a complex background produced by playing back a recorded flight in the Microsoft 2000 Flight Simulator (flight). In the second session, the backgrounds were the same, as were the amplitudes of the pursuit target. However, the frequencies of the sinusoids used to produce the smooth pursuit target were doubled. Gaze signals were digitized at 200Hz using scleral search coils. Results: For the first session, the mean of the horizontal standard deviations of retinal position error (difference between right eye and target positions) was 2.81 0.36 deg (dark) and 3.13 0.47 deg (flight). The vertical values were 3.06 0.53 deg (black) and 3.08 0.21 deg (flight). In session two, horizontal standard deviations were 5.74 0.38 deg (black) and 6.52 0.61 deg (flight). Vertical values were 5.10 0.44 deg (black) and 5.42 0.47 deg (flight). Conclusion: The simulated background had a significant detrimental effect on pursuit performance only for the more difficult target. This is most likely because target fixation is maintained less often with the difficult target, increasing the likelihood that the simulated background will draw attention away from the pursuit target.
Keywords: 409 eye movements: saccades and pursuits • 409 eye movements: saccades and pursuits • 326 attention