Visual and Spatial Components of Visual Working Memory Representations: An ERP study

We investigated the contribution of visual and spatial working memory (WM) subsystems in building a visual WM representation. To this aim we tested 15 participants in a color-change detection task by monitoring an electrophysiological marker of visual WM capacity: The Sustained Posterior Contralateral Negativity (SPCN). We compared two spatial arrangements of 2, 4 and 6 colored squares: 1. randomly positioned on a visual display or 2. organized in accordance with the Gestalt grouping principle of proximity. Behavioral results showed no significant differences between the two spatial arrangements. Notably, when compared the same number of stimuli, electrophysiological results showed larger SPCN amplitude in the random arrangement than in the organized arrangement. In addition, no significant interaction between spatial arrangement and the number of stimuli was observed. These data support the independence of the two distinct WM subsystems in building a visual WM representation.