Neural evidence for modality-independent storage in working memory.

Working memory (WM) is a core component of intellectual ability. Traditional behavioral accounts have argued that there remain distinct memory systems based on the type and sensory modality of information being stored. However, more recent work has provided evidence for a class of neural activity that indexes the number of visual items stored in a content-independent fashion. Here, across 2 electroencephalogram (EEG) experiments, we demonstrate an item-based signature of WM storage that generalizes across visual and auditory sensory modalities. Using multivariate techniques, we observed parallel but separate neural patterns that independently track stimulus modality, the number of items stored in WM (regardless of modality), and the number of spatially attended positions. We propose that these load signals reflect a modality-independent process for binding item representations to context, reinforcing accounts arguing for a distinction between the maintenance of the content of one's thoughts and the manipulation and gating of those thoughts.