Abstract
Visual working memory (VWM) is inherently limited, making it important to select and maintain relevant information and to protect it from distraction by suppressing irrelevant, distracting information. Previous work has suggested the contralateral delay activity (CDA) and lateralized alpha oscillations (8–14 Hz) as neural candidates of such a gating process. While most of this work has focused on distraction during encoding, we investigated the effect of distraction during the maintenance interval. Participants (n = 30) encoded three lateralized targets in VWM and maintained these targets over a 3 sec delay. Half-way through the delay, distractors appeared briefly at the same location as the targets or in the opposite hemifield. Behavioral performance was most impaired by same-side distractors, less impaired by opposite-side distractors, and least impaired by weak, non-lateralized control distractors. In the pre-distraction interval, larger CDA amplitudes generally reflected better performance irrespective of the type of upcoming distraction. However, in the post-distraction interval and specifically after same-side distractors, larger CDA amplitudes were associated with stronger performance impairment, reflecting the disruptive influence of the distractor. Conversely, after opposite-side distractors, larger CDA amplitudes were associated with better performance, indicating a stronger focus on the target location. By contrast, alpha lateralization was determined only by the location of the distractor, irrespective of the targets’ location. Importantly, we found no association between alpha lateralization and mnemonic performance. Our findings suggest that the CDA indexes not only the maintenance of recently encoded targets, but also the effective gating of distraction during maintenance. By contrast, alpha lateralization only indexes the current focus of spatial attention with no role in VWM-related gating.