The content of visual working memory alters processing of visual input prior to conscious access: evidence from pupillometry

Visual working memory (VWM) allows for keeping relevant visual information available after termination of its sensory input. Storing information in VWM, however, affects concurrent conscious perception of visual input: initially suppressed visual input gains prioritized access to consciousness when it matches the content of VWM (Gayet et al., 2013). Recently, there has been a debate whether such modulations of conscious access operate prior to conscious perception or, rather, during a transition period from non-conscious to conscious perception. Here, we used pupil size measurements to track the influence of VWM on visual input continuously, and dissociate between these possibilities. Participants were sequentially presented with two shapes drawn from different shape categories (ellipses, rectangles, or triangles) and a retro-cue, indicating which of the two shapes should be remembered for subsequent recall. During the retention interval, participants were instructed to report whether a target shape, which either matched or mismatched the concurrently memorized item, was presented left or right of fixation. Critically, the target shape was initially suppressed from consciousness by continuous flash suppression, and could therefore only be responded to once it was consciously accessible. Analyses of response times revealed that targets were released from suppression faster when they matched compared to when they mismatched the memorized shape. This behavioral effect was paralleled by a differential pupillary response such, that pupil constriction was more pronounced when visual input matched compared to when it mismatched the content of VWM. Importantly, this difference in pupil size emerged already 500ms after target onset, and almost two seconds before participants could report the location of the target shape. We conclude that the content of VWM affects processing of visual input when it is not yet consciously accessible, thereby allowing it to reach prioritized conscious access. Meeting abstract presented at VSS 2017.