Task-Dependent Representation of Features within the Same Dimension in Visual Working Memory

Working memory (WM) serves as a neurocognitive system responsible for temporarily storing and manipulating information when its source has disappeared. Previous investigations into whether features within the same dimension were stored separately or conjoined into objects have yielded conflicting findings. Based on increasing evidence on the adaptivity of the working memory system, we conjectured that the format in which objects from the same dimension are stored in Visual Working Memory (VWM) might be contingent on the specific task demands, and subtle distinctions across experiments may account for the disparities in results. In the current study, we introduced modifications to the paradigm used by Luck and Vogel (1997) and Wheeler and Treisman (2002), where the same paradigm led to different conclusions, to assess whether implicit task requirements could influence the storage format of objects in visual working memory. In two conditions, we manipulated the relevance of conjunction between two colors by varying the proportions of Mis-conjunct probes, a probe type depending on conjunction information for accurate responses. The results showed that in both conditions, performance was primarily determined by the number of features rather than the number of objects, aligning with the results of Wheeler and Treisman. Nevertheless, we observed that Mis-conjunct probes, which require conjunction information, exhibited improved performance when tested more frequently. This suggests that the format of retention in working memory, whether in separate or conjoined form, is influenced by the task demands.