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With the scleral search coil technique, we recorded ocular following responses elicited by either grating or plaid pattern motions. Grating motion elicited tracking responses at short latencies ( approximately 85 msec). Type I plaid motion made by summing two orthogonal moving gratings elicited ocular following with identical short latencies. Trial-by-trial(More)
The perceived direction of a grating moving behind an elongated aperture is biased towards the aperture's long axis. This "barber pole" illusion is a consequence of integrating one-dimensional (1D) or grating and two-dimensional (2D) or terminator motion signals. In humans, we recorded the ocular following responses to this stimulus. Tracking was always(More)
Primates use vergence eye movements to align their two eyes on the same object and can correct misalignments by sensing the difference in the positions of the two retinal images of the object (binocular disparity). When large random-dot patterns are viewed dichoptically and small binocular misalignments are suddenly imposed (disparity steps), corrective(More)
We investigated the effects of stationary and moving textured backgrounds on ocular and manual pursuit of a discrete target that suddenly starts to move at constant speed (ramp motion). When a stationary textured background was superimposed to the target displacement, the gain of the steady-state eye smooth pursuit velocity was significantly reduced, while(More)
When human subjects are presented with visual displays consisting of random dots moving sideways at different velocities, they perceive transparent surfaces, moving in the same direction but located at different distances from themselves. They perceive depth from motion parallax, without any additional cues to depth, such as relative size, occlusion or(More)
We present the first assessment of motion vision in childhood autism. Postural reactivity to visually perceived motion was measured in five autistic children and 12 normal controls of the same chronological age. Anteroposterior as well as total body sway occurring on a force platform in response to movements in the visual environment were compared. Autistic(More)
Primates can generate accurate, smooth eye-movement responses to moving target objects of arbitrary shape and size, even in the presence of complex backgrounds and/or the extraneous motion of non-target objects. Most previous studies of pursuit have simply used a spot moving over a featureless background as the target and have thus neglected critical issues(More)
Motion transparency requires that the visual system distinguish different motion vectors and selectively integrate similar motion vectors over space into the perception of multiple surfaces moving through or over each other. Using large-field (7 degrees x 7 degrees) displays containing two populations of random-dots moving in the same (horizontal) direction(More)
The dynamics of attentional deployment before saccade execution was studied with a dual-task paradigm. Observers made a horizontal saccade whose direction was indicated by a symbolic precue and had to discriminate the orientation of a Gabor patch displayed at different delays after the precue (but before saccade onset). The patch location relative to the(More)
Pursuing an object with smooth eye movements requires an accurate estimate of its two-dimensional (2D) trajectory. This 2D motion computation requires that different local motion measurements are extracted and combined to recover the global object-motion direction and speed. Several combination rules have been proposed such as vector averaging (VA),(More)