Mohammad Shams^1,4 (), Aurore Maloh², Peter Kohler^3,4, Patrick Cavanagh^1,4; ¹Glendon College, York University, Toronto, ON, Canada, ²Faculty of Health, York University, Toronto, ON, Canada, ³York University, Toronto, ON, Canada, ⁴Centre for Vision Research, York University, Toronto, ON, Canada

Moving objects shift the perceived position of nearby flashes (Whitney & Cavanagh, 2000). We presented bars rotating around the center of gaze and flashed dots at different locations and times relative to the bars. We found that flashes presented ahead of a moving bar were shifted in the direction of the bar's motion, peaking for probes 15 degrees of rotation ahead of the bar, while flashes presented behind the bar remained largely unaffected (similar to Watanabe et al., 2003; Durant & Johnston, 2004). It has previously been proposed (Shams, Kohler, & Cavanagh, ECVP 2023) that this anisotropic position shift is due to attentional repulsion (Suzuki & Cavanagh, 1997) where, in this case, the focus of attention leads the moving object. Here, we further tested the role of attention by varying the number of bars and flashes and by introducing a spatial cue at the center pointing to the physical location of the target, presented either before (pre-cue) or after (post-cue) the bar’s motion. In the post-cue condition, we observed a large position shift (~1.7 dva) that did not differ between the one-bar and four-bar conditions. In contrast, in the pre-cue condition, the position shift decreased (~7%) in the one-bar condition and increased (~12%) in the four-bar condition compared to the post-cue conditions. The lack of effect of the number of probes in the post-cue conditions suggest that exogenous attention must be involved because exogenous attention can be unaffected by attentional load (Wright, 1994; Solomon, 2004). The pre-cue conditions suggest that endogenous attention may also play a role by either modulating the position shift by reallocating resources between the moving object and the probe location (as proposed by Adamian & Cavanagh, 2024) or by increasing the speed at which the probe location can be retrieved (Müsseler & Aschersleben, 1998).