Abstract
Goal The timing of visual events is often predictable, allowing observers to voluntarily attend to relevant points in time. Voluntary temporal attention increases perceptual sensitivity, but the underlying dynamic processes are unclear. Microsaccades, or small fixational eye movements, are thought to contribute to the active sampling of visual information and can be modulated by expectations. Here we asked whether voluntary temporal attention affects the rate and timing of microsaccades. Methods In different experiments two or three oriented grating targets (T1, T2, T3) were presented sequentially, 250 ms apart, in the same spatial location on each trial. A precue tone 1000 ms before T1 indicated which target was likely to be probed. A postcue tone 500 ms after T2 or T3 indicated which target's orientation to report. In valid trials (60%), the precue and postcue matched, in invalid trials (20%), they did not match, and in neutral trials (20%), the precue was uninformative as the targets were equally likely to be probed. Trials with blinks or large saccades were rejected online and repeated later in the session. Microsaccades were identified offline. Results Temporal cueing improved orientation judgment accuracy. For all cueing conditions, microsaccade rate decreased approximately linearly during the 500 ms before T1 and remained near zero until rebounding 300-500 ms after T1. Microsaccades were fully inhibited earlier and rebounded earlier given a T1 precue compared to a neutral, uninformative precue. In addition, the microsaccade rate was lower in the T1 compared to the neutral cueing condition during the 500 ms before T1. Conclusions Voluntary temporal attention changes microsaccade rate and timing, reflecting a cognitive influence on the rate and precise timing of fixational eye movements, even when no target stimulus is physically present.
Meeting abstract presented at VSS 2018