Do Visual Cues Contribute to the Neural Estimate of Viewing
Distance Used by the Oculomotor System?
Min Wei, Gregory C. DeAngelis, and Dora E. Angelaki
Department of Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110
Perceived shape and depth judgments that require knowledge of viewing distance are strongly influenced by both vergence angle and the
pattern of vertical disparities across large visual fields. On the basis of this established contribution of visual cues to the neural estimate
hypothesis, we investigated how compensatory eye movements during whole-body translation scale with viewing distance. Monkeys
viewed large-field (85 68°) random-dot stereograms that were rear projected onto a fixed screen and simulated either a textured wall
or pyramid at different viewing distances. In these stereograms, we independently manipulated vergence angle, horizontal and vertical
projected onto a moveable screen placed at different physical distances from the animal. Several cycles of leftright sinusoidal motion of
viewing distance was quantified. As expected from previous work, the amplitude of compensatory eye movements depended strongly on
vergence angle. Although visual cues to distance had a statistically significant effect on eye movements, these effects were 20-fold
distance and that the oculomotor system relies far less on visual cues than the perceptual system.
Key words: eye movement; binocular; vestibular; vestibuloocular; vergence; stereopsis; distance perception