Abstract
To maintain visual stability, the retinotopic coordinates of objects need to be remapped across each saccade. Recent evidence suggests that visual attention is also remapped, occurring in two stages: a fast remapping to the new retinotopic location followed by a slower disengagement from the prior representation (i.e., retinotopic trace; Golomb, L'Heureux, & Kanwisher, 2014). However, it remains unclear how the focus of attention is dynamically shifted over the entire perisaccadic period. In the current study, we recorded steady-state visual evoked potentials (SSVEP) in human EEG to dynamically read out which objects subjects were attending to across each saccade. Three orientation gratings were displayed on the screen with two possible fixation locations between them ("O+O+O" pattern). Subjects maintained attention on the central patch and reported an occasional orientation shift. In half of the trials, subjects also made a saccade from one fixation point to the other as soon as a saccade cue appeared. Thus, the central patch was the spatiotopic (attended) location, while the other two patches represented the "predictive-remapping location" and "retinotopic-trace location" respectively. All three patches flickered at different frequencies, such that each location was tagged with a unique SSVEP spectral peak. Time-frequency analysis was performed on EEG data to calculate the inter-trial coherence (ITC) corresponding to each location over time. ITC was greatest at the spatiotopic (attended) location during baseline periods (outside the perisaccadic window), indicating that subjects were successfully attending to the spatiotopic location. Immediately after each saccade, the ITC difference between the spatiotopic location and retinotopic-trace location was reduced, consistent with a temporary lingering of attention at the retinotopic-trace location subsequent to each saccade. Preliminary data also found weaker evidence for predictive remapping. The current experiment provides a new method to dynamically track the neural signatures of visual attention across a saccade.
Meeting abstract presented at VSS 2017