Probing bimodal working memory
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How is information coming from multiple modalities maintained in working memory (WM)? Although we perceive the world through multiple senses, research on working memory has mainly focused on senses in isolation. In three retro-cue experiments we probed working memory sensitivity for low-level audiovisual features (oriented gratings and tone frequencies). In a first behavioral experiment maintaining bimodal information in WM revealed no interference: memory sensitivity was equal to maintaining unimodal information. In a second behavioral experiment, we showed that when unimodal components are arbitrarily bundled into bimodal objects, bimodal WM performance improved relative to unimodal stimuli. A follow-up model comparison suggests that participants flexibly relied on the ‘best’ unimodal component. Finally, to investigate how bimodal WM impacts representation of unimodal information in the brain, we tested the experiment 1 in a fMRI pilot (N=1). Using multivariate pattern analysis, we found that visual orientation could be decoded from WM in the visual cortex only in those trials where visual information needed to be prioritized. Summarizing, our behavioral results suggest that bimodal WM does not impair the precision of the unimodal components. This is compatible with independent modality-specific stores. Further fMRI data collection is needed to draw conclusions about how bimodal working memory is implemented in the brain.
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