Contralateral delay activity as a marker of visual working memory capacity: a multi-site registered replication

Visual working memory (VWM) is a temporary storage system capable of retaining information that can be accessed and manipulated by higher cognitive processes, thereby facilitating a wide range of cognitive functions. Electroencephalography (EEG) is used to understand the neural correlates of VWM with high temporal precision, and one commonly used EEG measure is an event-related potential called the contralateral delay activity (CDA). In a landmark study by Vogel and Machizawa (2004), the authors found that the CDA amplitude increases with the number of items stored in VWM and plateaus around three to four items, which is thought to represent the typical adult working memory capacity. Critically, this study also showed that the increase in CDA amplitude between two-item and four-item arrays correlated with individual subjects’ VWM performance. Although these results have been supported by subsequent studies, a recent study suggested that the number of subjects used in experiments investigating the CDA may not be sufficient to detect differences in set size and to provide a reliable account of the relationship between behaviorally measured VWM capacity and the CDA amplitude. To address this, the current study, as part of the #EEGManyLabs project, aims to conduct a multi-site replication of Vogel and Machizawa's (2004) seminal study on a large sample of participants, with a pre-registered analysis plan. Through this, our goal is to contribute to deepening our understanding of the neural correlates of visual working memory

Items in visual working memory are more susceptible to visual interference while in-use.

Despite the importance of visual working memory (VWM) in supporting everyday behavior, it can be susceptible to interference: Perceptual distractors appearing during maintenance can impair the integrity of representations stored in VWM. There are mechanisms to help protect representations, such as reinforcing an item with a retroactive cue (retro-cue). Critically, previous work focused on the protection of inactive VWM representations—representations that are maintained over a delay period but are not being actively used during the delay period. Our world, however, is dynamic, often requiring active use/manipulation of items in VWM. Can in-use VWM representations be protected against perceptual interference? In the present study, participants remembered the orientations of two briefly presented colored bars. Subsequently, a colored retro-cue identified one bar as the target. Subjects were then cued to mentally rotate the target: Two sequential rotation cues indicated the amount and direction to mentally rotate. On some trials, a colorful perceptual distractor appeared during the trial. Critically, we manipulated when in the trial sequence the distractor appeared, either during manipulation of the target bar or after manipulation was complete. Perceptual interference was measured as poorer orientation report performance on Distractor-present versus Distractor-absent trials. We observed robust perceptual interference when the distractor appeared while the item was in-use (during VWM manipulation), but not when the distractor appeared once the item was no longer in-use. The results suggest that VWM items are not protected from visual interference while they are in-use, but they can be protected once they are no longer in-use