Are irrelevant items actively deleted from visual working memory?: No evidence from repulsion and attraction effects...

Some theories propose that working memory (WM) involves the active deletion of irrelevant information, including items that were retained in WM, but are no longer relevant for ongoing cognition. Considerable evidence suggests that active-deletion occurs for categorical representations, but whether it also occurs for recall of features that are typically bound together in an object, such as line orientations, is unclear. In two experiments, with or without binding instructions, healthy young adults maintained two orientations, focused attention to recall the orientation cued first, and then switched attention to recall the orientation cued second, at which point the uncued orientation was no longer relevant on the trial. In contrast to the active-deletion hypothesis, the results showed that the no-longer-relevant items exerted the strongest bias on participants' recall, which was either repulsive or attractive depending on both the degree of difference between the target and nontarget orientations and the proximity to cardinal axes. We suggest that visual WM can bind features like line orientations into chunked representations, and an irrelevant feature of a chunked object cannot be actively deleted - it biases recall of the target feature. Models of WM need to be updated to explain this and related dynamic phenomena.