Abstract
Purpose. During saccade preparation, visual sensitivity at the saccade target is enhanced. Here, we used reverse correlation to investigate whether and how saccade preparation modulates gain, orientation tuning and spatial frequency tuning at the saccade target. Method. Observers performed a detection task on test stimuli presented at one of two locations (10° left or right from fixation). The target was a vertical grating (0.8° Gaussian envelope; 1.5 cpd) presented in half of the trials, and embedded in random noise. In the saccade blocks, a central pre-cue instructed observers to saccade to the cued location. After a random SOA (12-224 ms) following the cue, the test stimulus (noise or noise+target) flashed briefly at the cued location. In the neutral blocks, a central pre-cue pointed to both locations and observers maintained fixation throughout the trial. Results. We analyzed the data time-locked to the saccade onset. When the target was presented in a critical presaccadic interval (within 50 ms before saccade onset), observers' d' in the saccade condition significantly improved, compared to the neutral condition. Using reverse correlation analysis, we found that saccade preparation affected sensitivity to orientation and spatial frequency information: i) orientation: enhanced gain and narrowed tuning width. ii) spatial frequency: shift of the tuning peak toward higher spatial frequencies. By analyzing the orientation tuning and spatial-frequency tuning at multiple presaccadic time windows, we found that the reduction of the orientation-tuning width and the shift of the spatial-frequency-tuning peak became more pronounced as time approached saccade onset. Conclusion. Upcoming eye movements altered visual processing: Enhanced visual sensitivity at the saccade target was mediated by enhanced gain, sharpened orientation tuning and a shift of spatial-frequency tuning, which were dynamically modulated during the presaccadic interval.
Meeting abstract presented at VSS 2016