From Following Edges to Pursuing Objects
Open Access
- 1 November 2002
- journal article
- clinical trial
- Published by American Physiological Society in Journal of Neurophysiology
- Vol. 88 (5), 2869-2873
- https://doi.org/10.1152/jn.00987.2001
Abstract
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 associated with the general problem of recovering object motion. Visual psychophysicists and theoreticians have shown that, for arbitrary objects with multiple features at multiple orientations, object-motion estimation for perception is a complex, multi-staged, time-consuming process. To examine the temporal evolution of the motion signal driving pursuit, we recorded the tracking eye movements of human observers to moving line-figure diamonds. We found that pursuit is initially biased in the direction of the vector average of the motions of the diamond's line segments and gradually converges to the true object-motion direction with a time constant of approximately 90 ms. Furthermore, transient blanking of the target during steady-state pursuit induces a decrease in tracking speed, which, unlike pursuit initiation, is subsequently corrected without an initial direction bias. These results are inconsistent with current models in which pursuit is driven by retinal-slip error correction. They demonstrate that pursuit models must be revised to include a more complete visual afferent pathway, which computes, and to some extent latches on to, an accurate estimate of object direction over the first hundred milliseconds or so of motion.Keywords
This publication has 11 references indexed in Scilit:
- Temporal dynamics of a neural solution to the aperture problem in visual area MT of macaque brainNature, 2001
- Visual Motion Integration for Perception and PursuitPerception, 2000
- Motion coherence affects human perception and pursuit similarlyVisual Neuroscience, 2000
- Temporal dynamics of motion integration for the initiation of tracking eye movements at ultra-short latenciesVisual Neuroscience, 2000
- Initiation of saccades during fixation or pursuit: evidence in humans for a single mechanismJournal of Neurophysiology, 1996
- Different motion sensitive units are involved in recovering the direction of moving linesVision Research, 1993
- A psychophysically motivated model for two-dimensional motion perceptionVisual Neuroscience, 1992
- Relation of cortical areas MT and MST to pursuit eye movements. II. Differentiation of retinal from extraretinal inputsJournal of Neurophysiology, 1988
- Visual Motion Processing and Sensory-Motor Integration for Smooth Pursuit Eye MovementsAnnual Review of Neuroscience, 1987
- The relationship between saccadic and smooth tracking eye movementsThe Journal of Physiology, 1961