Abstract
Several neural indices have been used to track aspects of performance during tasks that tax visual working memory, but the role of EEG alpha-band activity in the actual storage of representations in visual working memory has been highly debated. For example, recent competing views suggest that alpha-band oscillations index working memory representations or the focus of attention. Here, we used a lateralized spatial estimation task, in which two colored dots were presented sequentially to one side of fixation to test competing predictions of these views. During the task, we recorded EEG data and measured the contralateral delay activity (CDA) to provide a canonical measure of working memory storage, along with bilateral and lateralized alpha oscillations. Additionally, we used a linear discriminant classifier to determine if multivariate analysis of alpha-band activity across the scalp could decode spatial locations of multiple working memory representations when items were presented sequentially. We found that CDA amplitudes increased with object load similar to the multivariate analysis, suggesting that multivariate patterns of alpha activity may code for the storage of information in working memory while univariate alpha activity measures a different cognitive mechanism.