Lijing Guo^1,2, Ruyi Liu¹, Dan Nie¹, Chaoxiong Ye^1,3; ¹University of Jyvaskyla, Jyvaskyla, Finland, ²Anyang Normal University, Anyang, China, ³Sichuan Normal University, Chengdu, China

Identical memory items can potentially reduce the cognitive demands on visual working memory (VWM) and enhance its memory performance. While previous studies have preliminarily explored this topic, controversy remains, particularly regarding the generalizability of these benefits to complex stimuli. This study further investigates whether identical items within the memory range reduce the number of items maintained in VWM and explores the conditions under which this effect occurs. Participants performed a change detection task, memorizing the orientations of memory arrays under three conditions: (1) four identical orientations, (2) two pairs of identical orientations, and (3) four different orientations. By examining contralateral delay activity (CDA), an event-related potential component that reflects the real-time number of items stored in VWM, we observed that in the late time window, the CDA amplitude was significantly lower for the all-identical condition compared to the partial-identical and all-different conditions, with no significant difference between the latter two. However, there was no significant difference across the three conditions during the early time window. Our findings suggest that, during the early stages of VWM consolidation, individuals tend to encode as many items as possible from the visual field. However, in later consolidation stages, the VWM system processes identical information to reduce the number of maintained items. This effect, however, only applies when all items in the visual field are identical. When only some items are identical, directly storing all items is more efficient than first identifying identical ones and then processing them.

Acknowledgements: This work was supported by the Research Council of Finland (former Academy of Finland) Academy Research Fellow project (#355369 to Chaoxiong Ye) and Finnish Cultural Foundation (#00231373 to Chaoxiong Ye).