Abstract
Most natural objects we pursue are larger than the spot pursuit stimulus, and extend beyond the fovea. Given, the pursuit system might benefit from the peripheral motion information they provide. Previous work showed that additional peripheral motion improves identification of or reduces saccade latency to changes in features of a pursuit stimulus, a result attributed to a motion releasing attention from the pursuit target to perform the tasks. We asked whether this attention was specific to the visuomotor system, or whether it was shared with a cognitive pool. To test this, observers performed a secondary letter memorization task during pursuit. The pursuit stimulus comprised a small (0.26 °) square and four surrounding spots (0.2°) (3.7° eccentricity) arranged in an ‘X’ configuration, that moved at 12 °/s and was presented with or without consistent peripheral motion of a random dot cinematogram (RDC). First, observers pursued the stimulus and made a saccade to one of the surrounding four spots that was brightened. Consistent with previous work, saccade latency was reduced by the RDC, an indicator of how much attention was released from pursuit. Task difficulty was then decreased by increasing the luminance of the target spot, which eliminated the latency reduction provided by the motion. Next, observers performed the memory task in which two letters were briefly presented before each eye movement trial. Observers had to remember the letters from both the current and previous trials throughout the eye movement task, and following the current trial, identify the letters from the previous one. Adding the memory task restored the benefit of peripheral motion to saccade latency. The results suggest that attentional resources usurped by the memory task left insufficient resources for the eye movement task, and therefore attentional resources for pursuit and cognition are shared.