Tracking the unconscious: Neural evidence for the retention of unaware information in visual working memory

This study investigates the retention of visual information in visual working memory (VWM) when individuals are unaware of it, aiming to provide clear-cut evidence for an unconscious VWM effect. To explore the underlying neural mechanisms, we monitored a critical event-related potential (ERP) component, specifically the contralateral delay activity (CDA), which reflects VWM maintenance. Participants performed a change detection task in which to-be-memorized Gabor patches were presented at a visibility threshold, determined to assess subjective awareness using the perceptual awareness scale (PAS). Participants performed above chance level in the change detection task even when the visibility of the Gabor patches was subthreshold, indicating retention of visual information without conscious awareness. Notably, in a subsample of participants, a reliable CDA amplitude was observed during unaware trials, in which participants performed correctly, compared to trials with incorrect responses. As a proof of concept, this finding indexed short active maintenance of unaware visual information in VWM, which could be used to perform VWM-based tasks. In conclusion, the results of our study support the existence of an active retention of unaware visual information in VWM. These findings challenge the notion of entirely activity-silent working memory by showing that unconscious information is maintained through active neural firing (CDA), potentially transitioning to activity-silent mechanisms in later phases.