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Eye Movement in Response to Single and Multiple Targets
Final rept. 1 Oct 1981-31 Dec 1983
MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF AERONAUTICS AND ASTRONAUTICS
Pagination or Media Count:
Two major studies were pursued under this research program one was devoted to eye-movement responses in multi-target situations, and the other to smooth scanning behavior when viewing eye-slaved targets. For multiple targets, a computer-controlled arc perimeter display comprised of 21 LED point targets 5 arc-minutes placed 5 degrees apart was utilized. Results showed that oculomotor reaction time increased from 200 ms for single targets to 240 ms for multiple targets 20 to 25 increase. Furthermore, delaying the appearance of one of the targets by 10 ms increased the reaction time even further, to about 300 ms. Further increases in second target delay produced a monotonically decreasing function of response time versus delay, until at delays of 100 ms, the reaction times were normal. For the experiments on eye-slaved target scanning behavior, the subject was presented with a target controlled by that persons own eye position. This eye-slaved target was then delayed 1 to 200 ms before being presented to the subject. With no delay, subjects were able to move their eyes smoothly across the screen and back i.e., self-initiated smooth pursuit. Small delays 40 to 60 ms tended to increase the smooth pursuit oscillations in both velocity and amplitude. The results suggest that smooth pursuit is facilitated by small delays in the eye-position feedback signal. At larger delays 100-200 ms, smooth pursuit was not obtained. The implications of these results for eye- slaved, area-of-interest displays are discussed. Originator-supplied keywords include eye movement multiple targets oculomotor control reaction time saccadic latency saccades smooth pursuit visual scanning.
APPROVED FOR PUBLIC RELEASE