Inchara Manjunatha^1,2, Kevin Ortego³, Viola Störmer³, Sven Ohl¹, Martin Rolfs^1,2; ¹Humboldt-Universität zu Berlin, ²Berlin School of Mind and Brain, ³Dartmouth College

People can quickly process summary statistical information across individual features. These ensemble representations have been shown to be biased towards items at the center of gaze suggesting that ongoing eye movements influence the way we perceive ensembles. Here, we examined the time course of this foveal bias following instructed saccades or prolonged fixations. We presented a stimulus consisting of oriented lines for 200 ms and participants reported their mean orientation under two viewing contexts: after an instructed saccade or while maintaining fixation. When saccades were required, the stimulus appeared gaze-contingently with a stimulus onset asynchrony (SOA) of 0, 50, 100, or 200 ms after online saccade detection. In the fixation condition, a temporal cue marked the upcoming stimulus onset using the same SOAs. Out of four quadrants in the ensemble, three contained orientations drawn from the same uniform distribution (standard quadrants), while the remaining quadrant contained orientations drawn from another uniform distribution with a mean shifted by 37.5° relative to the standard quadrant distribution (outlier quadrant). Unbeknownst to the participants, across an equal number of interleaved trials, the standard or the outlier quadrant was at the center of gaze. We expected reports of the ensemble mean to be biased toward the foveated quadrant, and for the magnitude of this bias to decrease with longer SOAs. Indeed, the foveated quadrant biased reports of the ensemble mean indicating that orientations across the visual field are not pooled uniformly. The bias was reduced at the 200 ms SOA relative to 0 ms, but showed no modulation by a recent saccade. Thus, while a longer delay between fixation and ensemble onset attenuated the foveal bias, similar performance across saccade and fixation trials suggests that orientations at the saccade target do not further influence ensemble perception beyond prolonged fixation.