Grzeczkowski, L. | Search bioRxiv

bioRxiv2023

The saccade-induced temporal attentional gradient: Duration compression of the post-saccadic second event

Rapid eye movements can distort our perception of time, as evidenced by the phenomenon of Chronostasis, where the first event following a saccade appears to last longer than it actually does. Despite extensive research on this phenomenon, the effect of saccades on sequential post-saccadic events, beyond the first one, has never been investigated. To address this, in the present study we compared the subjective estimates of the time of first and second post-saccadic events (with fixation conditions as controls). We found saccadic eye movements not only to affect the perceived duration of the first post-saccadic event (Chronostasis), but also that of the second event. Specifically, when the second event immediately following the first event, it was subjectively compressed. When the second event was used as the (constant) reference interval, Chronostasis was enhanced. Remarkably, the compression effect persisted even when potential "attentional-blink"-induced processes, that might affect timing at the transition from the first to the second event, were eliminated. To explain our findings, we propose that saccades induce a transient temporal attentional gradient that results in an overestimation of the first and an underestimation of the second interval when the two intervals are temporally (near-) contiguous.

neuroscience↗

bioRxiv2019

Stimulus blanking reveals transsaccadic feature transfer

Across saccadic eye movements, the visual system receives two successive static images corresponding to the pre- and the postsaccadic projections of the visual field on the retina. The existence of a mechanism integrating the content of these images is today still a matter of debate. Here, we studied the transfer of a visual feature across saccades using a blanking paradigm. Participants moved their eyes to a peripheral grating and discriminated a change in its orientation occurring during the eye movement. The grating was either constantly on the screen or briefly blanked during and after the saccade. Moreover, it either was of the same luminance as the background (i.e., isoluminant) or anisoluminant with respect to it. We found that for anisoluminant grating, the orientation discrimination across saccade was improved when a blank followed the onset of the eye movement. Such effect was however abolished with isoluminant grating. Additionally, performance was also improved when an anisoluminant grating presented before the saccade was followed by an isoluminant one. These results demonstrate that a detailed representation of the presaccadic image was transferred across saccades allowing participants to perform better on the trans-saccadic orientation task. While such a transfer of visual orientation across saccade is masked in real-life anisoluminant conditions, the use of a blank and of isoluminant postsaccadic grating allowed here to reveal its existence.\n\nSignificance statementStatic objects are perceived as not moving across eye movements despite their visual projection shifts on our retina. To compensate for such shifts and create a continuous perception of space, our brain may keep track of objects visual features across our movements. We found that shortly blanking a contrast-defined object during and after saccades allows to recover a detailed representation of its orientation. We propose that the transfer of visual content across saccades revealed with the use of a simple blank plays an important role in ensuring our continuous and stable perception of the world.

neuroscience↗