Abstract
The world appears stable despite frequent eye movements that change the location of visual input relative to eye position. Questions remain as to how the visual system integrates visual input while maintaining spatial attention across saccades. Recent work has examined whether visual attention is maintained across saccades in spatiotopic (world-centered) or retinotopic (eye-centered) coordinates. When subjects attend to a spatiotopic location, visual attention is initially maintained in retinotopic coordinates. However, retinotopic facilitation declines by 250 ms post-saccade, leaving only the task-relevant spatiotopic facilitation at later delays (Golomb, Chun, & Mazer, 2008, J. Neurosci.). The current study examined the spatiotemporal dynamics of this shift by probing an intermediate location to determine whether attentional facilitation transitions discretely from retinotopic to spatiotopic locations or expands to encompass spatiotopic, retinotopic, and intermediate locations. Subjects executed a guided saccade while holding a cued spatiotopic location in memory. After the saccade, subjects made a speeded orientation discrimination response to a probe that appeared at 50, 250, or 400 ms post-saccade. The oriented probe appeared at the attended spatiotopic location, the retinotopic location, an intermediate location between the spatiotopic and retinotopic locations, or eccentricity-matched control locations. Subjects were explicitly and implicitly biased towards maintaining attention in spatiotopic coordinates. Consistent with previous findings, the response time to a probe at the retinotopic location was facilitated over the control location immediately after the saccade. This retinotopic facilitation declined by later delays, while the task-relevant spatiotopic location remained facilitated at all tested delays. Facilitation at the intermediate location was less than at retinotopic and spatiotopic locations and did not vary in a time-dependent manner. These findings suggest that top-down attention can result in enhancement of discrete retinotopic and spatiotopic locations without spreading across intermediate locations.
NIH EY014193, NIH NRSA, NSF GRF, Whitehall Foundation.