Zeynep Karagül¹ (), Bilge Sayim², Nihan Alp¹; ¹Sabanci University, Istanbul, ²École Normale Supérieure (ENS), PSL University, CNRS

Visual perception does not operate uniformly across the visual field. Peripheral vision–compared to foveal vision–has lower spatial resolution, stronger crowding, and different temporal processing. Temporal processing differences across the visual field, such as the perceived timing of dynamic stimuli, could plausibly influence whether two events are perceived as synchronous. Here, we investigated whether the perceived synchrony of two dynamic faces is influenced by their locations in the visual field. We conducted two experiments in which participants judged whether two simultaneously presented faces were synchronous or asynchronous. In Experiment 1, we manipulated face-to-face distance (6°, 8°, 12°) in two conditions. Participants either fixated on the centrally presented face, while the other face was presented in the periphery (Center condition), or they fixated between the two peripheral faces, with one face at the same eccentricity in each hemifield (Symmetric condition). Sensitivity analyses revealed an interaction between fixation location and face-to-face distance. In the Center condition, sensitivity decreased with increasing distance. By contrast, sensitivity remained constant across distances in the Symmetric condition. These results indicate that –for the tested face-to-face distances– increased distances impaired synchrony perception only when one face was presented at the fovea and the other in the periphery. In Experiment 2, we compared eccentricity instead of face-to-face distance. The peripheral faces in both the Center and Symmetric conditions were presented at the same three eccentricities (6°, 8°, and 12°). We observed a robust main effect of eccentricity: sensitivity decreased with increasing eccentricity. Unlike in Experiment 1, this decrease did not differ between the Center and Symmetric conditions. Our findings show that synchronization sensitivity is limited more strongly by eccentricity than absolute face-to-face distance or fixation location. We suggest that the visual system compensates for inherent differences between foveal and peripheral vision, enabling effective integration of information across the visual field.

Acknowledgements: Z.K. and N.A. are supported by the Scientific and Technological Research Council of Turkey (TUBITAK 1001) under the Grant Number 122K922.