Binding in visual working memory is task dependent

Working memory is a neurocognitive system for maintaining and manipulating information online for a short period after the source of information disappears. The information held in working memory has been shown to flexibly match current functional goals. Considering this, we revisited the question of whether information is held in working memory as separate features or as bound objects. We conjectured that, rather than having a fixed answer, the format in which information is maintained in working memory is also task dependent. In two separate experiments, we investigated the binding between features when the location was not (Experiment 1, color and orientation binding) or was (Experiment 2, color and location binding) a task-relevant feature in a delayed (yes/no) recognition task by manipulating the relative relevance of conjunctions and separate features. Each experiment included two conditions: binding dominant (BD), which emphasized the retention of binding between features, and feature dominant (FD), which emphasized the retention of individual features. In both experiments, we found that memory for conjunctions was better in the BD condition and that memory for separate features was better in the FD condition. These patterns suggested that the formats of objects in visual working memory could be shaped by the tasks they serve. Additionally, we found that the memory of location was impaired when the conjunction between location and color was task irrelevant, whereas the memory of color and the memory of orientation were relatively independent of each other. We conclude that the representation format of objects in working memory is influenced by task requirements.