Storage in Visual Working Memory Recruits a Content-Independent Pointer System

• Published in: Psychological science Vol. 33; no. 10; pp. 1680 - 1694
• Main Authors: Thyer, William, Adam, Kirsten C. S., Diaz, Gisella K., Velázquez Sánchez, Itzel N., Vogel, Edward K., Awh, Edward
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01.10.2022; SAGE PUBLICATIONS, INC
• Subjects: Cognitive load; Electroencephalography; Individual differences; Memories; Multivariate analysis; Recruits; Research subjects; Short term memory; Stimulus; Topography; Tracking; visual working memory; open materials; spatiotemporal pointers; open data; electroencephalogram
• ISSN: 0956-7976; 1467-9280; 1467-9280
• DOI: 10.1177/09567976221090923

Past work has shown that storage in working memory elicits stimulus-specific neural activity that tracks the stored content. Here, we present evidence for a distinct class of load-sensitive neural activity that indexes items without representing their contents per se. We recorded electroencephalogram (EEG) activity while adult human subjects stored varying numbers of items in visual working memory. Multivariate analysis of the scalp topography of EEG voltage enabled precise tracking of the number of individuated items stored and robustly predicted individual differences in working memory capacity. Critically, this signature of working memory load generalized across variations in both the type and number of visual features stored about each item, suggesting that it tracked the number of individuated memory representations and not the content of those memories. We hypothesize that these findings reflect the operation of a capacity-limited pointer system that supports on-line storage and attentive tracking.