The geometry of working memory in action: Uncovering the latent structure of systematic and unsystematic errors with and without saccadic eye movements

Recent research emphasizes how working memory (WM) supports action in dynamic environments. But action almost always involves fast, "saccadic" eye movements that challenge WM representations, requiring spatial remapping and distorting spatial perception, especially along the saccade direction. To capture the impact of these distortions, we used a spatial WM task where participants, after a saccade or fixation, indicated remembered locations of memory items with a mouse. From the responses we extracted multiple measures of spatial error: response variability, shifts relative to the fixation point, rotations, compression and nonlinear distortions of space. These measures submitted to a principal component analysis (PCA) yielded two components: systematic and unsystematic spatial error both of which were correlated with established WM tasks, showing their relevance for WM fidelity. Systematic error revealed a centripetal shift, pulling towards spatial anchors like the fixation point and the memory array's centre of mass. This suggests that systematic error reflects a spatial scaffold that encodes relational information but is inherently imprecise. Saccades increased both error components and amplified WM load effects. Notably, we found that distortions of systematic error were especially pronounced along saccade direction for items that were remapped across visual fields, implying that WM fidelity is more vulnerable when information needs to pass through the corpus callosum. Together, our findings are consistent with the idea of WM actively reconstructing spatial information. They offer new insights into how saccades and spatial remapping shape WM in a dynamic world.