Neural Reinstatement of Features in Audiovisual Working Memory Indicates Object-based Retrieval

Selective attention allows us to prioritize or retrieve task-relevant features and items from working memory. However, previous work has largely relied on unisensory paradigms, leaving open the question of how attentional mechanisms act on audiovisual working memory representations. Here, using an EEG-based audiovisual delayed-match-to-sample task, we investigate whether attention to audiovisual working memory contents operates on the level of individual unisensory features or bound cross-modal objects. On each trial, participants memorized an audiovisual item. At test, they were randomly presented with either an auditory, visual, or audiovisual probe stimulus and indicated whether the latter matched their working memory content. Compared with recalling the entire audiovisual object, recall of unisensory visual or auditory features resulted in poorer behavioral performance and elevated midfrontal theta power. Multivariate pattern analyses (MVPAs) showed that task-irrelevant feature representations were retrieved in both auditory and visual probe trials, consistent with object-based retrieval. Moreover, these results shed light on the representational structure underlying cross-modal feature storage in working memory, suggesting that audiovisual features are stored as bound objects and that attentional selection of individual object features in one modality spreads to cross-modal object features in another modality. In task conditions where such incidental recall of task-irrelevant features is detrimental to task performance, this places greater demands on cognitive control mechanisms.