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Lyudmyla Kovalenko, Niko Busch; Probing the dynamics of perisaccadic perception with EEG. Journal of Vision 2014;14(10):1226. doi: 10.1167/14.10.1226.
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© ARVO (1962-2015); The Authors (2016-present)
Perceptual stability is a phenomenon that defines our subjective visual experience: as we navigate through the environment, the visual image appears spatially and temporally continuous. In reality, however, it is fragmented into separate fixational images that are displaced with each saccade. How are these discrete retinal snapshots connected to create a continuous percept? Two physiological processes that have been shown to shape perisaccadic perception are pre-saccadic shift of attention and saccadic suppression. While the attentional shift enhances visual sensitivity, saccadic suppression inhibits it to minimize retinal blur. Both processes are transient and active already before saccade onset. In our study, we probed the dynamic interplay of these two effects using electroencephalography (EEG) co-registered with eye tracking. Participants fixated on a central cross until cued to make a rightward or leftward saccade to target. At 220 ms after cue onset, a probe stimulus (checkerboard) was flashed for 30 ms in the left or right hemifield. All subsequent analyses were restricted to trials on which the saccade followed probe presentation. For these trials, we computed the lateralization patterns of probe-evoked EEG potentials, i.e. amplitude differences between electrodes contralateral vs. ipsilateral to the probe. Lateralization was compared between trials on which probe and saccade target appeared in the same or in different hemifields. In the early pre-saccadic period (100-140 ms after probe onset), we found stronger lateralization for probes that appeared in the same hemifield as the saccade target, indicating an effect of a perisaccadic attention shift. In the later pre-saccadic period (after 140 ms), we observed a transient reduction in lateralization independent of probe position that we attribute to perisaccadic suppression.
Meeting abstract presented at VSS 2014
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