EXPRESS: The Critical Role of Spatial Working Memory in Mental Rotation: Evidence from a Dual-Task Paradigm

Shared neural mechanisms underlie working memory (WM) and visual mental imagery (VMI) processes, yet their functional relationship remains debated, particularly regarding the contributions of visual and spatial WM to VMI. The present study employed a dual-task paradigm in which participants first maintained either visual (VWM) or spatial (SWM) information under varying memory loads (low vs. high), and subsequently performed mental rotation (MR) trials with different rotation angles. Consistent with the literature, a main effect of rotation angle on MR performance was observed, confirming the engagement of MR processes in both conditions (SWM-MR and VWM-MR). Notably, when participants were required to retain spatial information, MR accuracy was reduced in the SWM-MR condition. In contrast, no comparable impairment was observed in the VWM-MR condition. These findings suggest that MR task performance in the present paradigm is more vulnerable to concurrent spatial than visual working-memory demands, thereby helping to clarify the relationship between WM and VMI.