Paul Schmitthäuser^1,2 (paul.schmitthaeuser@hu-berlin.de), Martin Rolfs¹, Nina M. Hanning¹; ¹Humboldt-Universität zu Berlin, ²Freie Universität Berlin

We generate saccadic eye movements at a baseline rate of approximately 2 to 4 per second. Sudden visual transients reliably interrupt this stream of eye movements, producing a sharp suppression of saccade initiation—a phenomenon known as “saccadic inhibition”—that is followed by a rebound that briefly exceeds baseline. Although saccadic inhibition has been demonstrated in many visual tasks, it remains elusive how this inhibition interacts with the unfolding dynamics of saccade planning in naturalistic free viewing, and whether it depends on the spatial congruency between a transient and the current motor plan. Participants performed an unrestricted search task in which they freely explored an array (r=~14°) of 19 differently colored tiles until they found a hidden target. Tile colors signaled target probabilities and encouraged systematic, predictable gaze patterns. Brief luminance probes (8.3 ms) were flashed either at the current fixation location, the predicted saccade target, or a non-target location. The natural variability in probe timing relative to saccade onset allowed us to probe different phases of saccade preparation. Saccadic inhibition followed probe onsets at any location, regardless of congruency with the saccade target. Critically, however, recovery was faster when probes coincided with the upcoming saccade target than when they appeared at other locations. These results suggest that visual transients interact with naturalistic visual exploration in two temporally distinct ways: an initial, global pause that interrupts saccade initiation, followed by a spatially selective recovery that is facilitated when the transient is congruent with the current saccade plan. This pattern aligns with an architecture in which global inhibition temporarily halts saccade execution, while spatially selective motor priority is preserved and shapes the speed of recovery.

Acknowledgements: This research was supported by the European Research Council (ERC) under the European Union’s Horizon Europe research and innovation programme (project 101165343 – FREE-VIEW to NMH).