The neural mechanisms of active removal from working memory

The ability to frequently update the contents working memory (WM) is vital for the flexible control of behavior. Whether there even exists a mechanism for the active removal of information from working memory, however, remains poorly understood. In this Registered Report we will test the predictions of models for two different (and not mutually exclusive) mechanisms of active removal: adaptation-hijacking and mental-context shifting. We will collect functional magnetic resonance imaging (fMRI) data while subjects perform a novel "ABC-retrocuing" task designed to elicit two modes of removal, active or passive (Shan & Postle, Registered Report). The adaptation-hijacking model posits an adaptation-like modification of perceptual circuits combined with a weak activation of the to-be-removed item. Its predictions will be assessed by using multivariate inverted encoding modeling (IEM) and photic "pings" to assay the state of feature-selective encoding channels and of activity-silent representations under active-removal versus passive-removal conditions. A second model - "working memory episodic memory" (WMEM) - posits that interference from no-longer-relevant information is minimized by making the mental context associated with new information dissimilar from that associated with the to-be-"removed" information. This will be tested by using representational similarity analysis (RSA) to compare the rate of contextual drift under active-removal versus passive-removal conditions.