Abstract
Previously, we provided the pursuit system with an alternative drive to a foveal target using a large random dot cinematogram (RDC) stimulus that stimulated peripheral retina (Heinen et al., 2011). This manipulation improved performance on a secondary perceptual task during pursuit. The improvement was thought to occur because the RDC released foveal attention for the task, additionally implying that pursuit of an RDC requires less attention than does pursuit of a foveal target. If so, the RDC might preferentially activate subcortical rather than cortical neural circuitry. Since there is evidence that the cortical supplementary eye fields (SEF) are involved in generating anticipatory eye velocity (Missal &Heinen, 2004), it is possible that the RDC would not activate this region, and therefore produce less anticipatory eye movements. In the current study, observers pursued either a single spot stimulus, or a stimulus composed of a spot embedded in a large RDC. The stimulus moved at 20 deg/sec in a predictable direction. We found that anticipatory eye velocity was more prevalent, and was consistently higher for the single spot than for the RDC. We then increased attention at the fovea by having observers detect the dimming of the foveal target during pursuit. In this condition, anticipatory eye velocity was increased over that which occurred for pursuit of the spot without the task. The results suggest that anticipatory pursuit is facilitated during pursuit of the spot because attention is directed towards it, and further imply that pursuit of a large object requires less attention than does pursuit of a foveal one.
Meeting abstract presented at VSS 2012