Nina M. Hanning¹ (), Hyun Seo Lee², Marisa Carrasco²; ¹Humboldt-Universität zu Berlin, Department Psychologie, ²New York University, Department of Psychology & Center for Neural Science

When we prepare saccadic eye movements, attention shifts toward the upcoming fixation location, enhancing perceptual performance and appearance. Recent work shows that the saccade target benefit is accompanied by a cost at the current fixation, where overall perceptual performance is reduced shortly before we look away. It is unknown whether the foveal costs of saccade preparation are limited to performance or also extend to visual appearance. Here, we investigated the presaccadic time course of foveal performance and appearance using a two-by-two AFC task. Participants prepared horizontal saccades while viewing random dot kinematograms (RDKs) at the presaccadic center of gaze. During saccade preparation, a motion signal of varying coherence was briefly presented, and participants reported both its perceived direction (performance) and whether its coherence appeared weaker or stronger than a fixed reference signal presented earlier in the trial (appearance) with a single, combined response. Motion coherence was parametrically varied, and the timing of the motion pulse relative to the saccade cue was sampled across several presaccadic intervals. Psychometric functions were fitted separately for performance and appearance as a function of motion coherence and time. Consistent with previous results, performance at fixation deteriorated during saccade preparation: the coherence required to reach 80% correct accuracy increased progressively following the saccade cue, reflecting a growing performance cost. Appearance showed a closely matched pattern: the point of subjective equality (PSE) shifted systematically to higher coherence values over the course of saccade preparation, indicating a gradual reduction in perceived motion strength at fixation. Together, these findings show that saccade preparation produces parallel costs in both performance and appearance at the current center of gaze. Combined with established presaccadic benefits at the saccade target, the results support a redistribution account in which presaccadic attentional gains at the movement goal are mirrored by concurrent perceptual costs at fixation.

Acknowledgements: This research was supported by a Marie Skłodowska-Curie individual fellowship by the European Commission (898520) to NMH.