Jiacheng Hao^1,2, David Melcher^2,4, Marisa Carrasco^1,3; ¹Department of Psychology, New York University, New York, USA, ²Department of Psychology, New York University Abu Dhabi, Abu Dhabi, UAE, ³Center for Neural Science, New York University, New York, NY, USA, ⁴Center for Brain and Health, New York University Abu Dhabi, Abu Dhabi, UAE

[BACKGROUND] Saccadic Inhibition (SI), the transient suppression of saccade generation that follows an abrupt visual transient (distractor), is a fundamental mechanism of oculomotor control. This inhibition typically peaks at ~90ms post-distractor-onset and is followed by a brief saccade rebound above baseline. Although SI is known to depend on the distractor’s physical properties and its spatial relation to the planned saccade, it remains unknown whether SI exhibits typical polar-angle asymmetries–better performance along the horizontal than the vertical meridian and along the lower than the upper vertical meridian. We investigated whether these perceptual asymmetries influence the magnitude and temporal profile of SI. [METHODS] We conducted two experiments in which participants made saccades to peripheral Gabor targets. Shortly after target onset, a larger Gabor distractor was flashed at a different location to induce SI. To isolate asymmetries related to saccade direction from those related to distractor location, we manipulated their spatial configuration. Participants made a saccades to one of four cardinal locations while a distractor appeared at one of four intercardinal locations. We quantified the magnitude and temporal profile of SI as a function of target and distractor locations. [RESULTS] SI emerged across all target and distractor locations, with the maximum inhibition occurring ~100 ms after distractor onset. For saccade direction, upward saccades exhibited weaker inhibition than the other cardinal directions, regardless of distractor location. Moreover, overall there was a stronger SI with upper-field than lower-field distractors. [CONCLUSION] The results showed that both target and distractor location modulate the timing and magnitude of SI. These findings suggest that to comprehensively understand the SI phenomenon, and its neural correlates, we should consider saccade direction. To further investigate this issue, we will also present results of a reversed condition-intercardinal target and cardinal distractor locations.

Acknowledgements: Funded by the Global PhD Fellowship, New York University Abu Dhabi to author J.H.