Dissociable Effects of Attention and Prediction on Visual Processing: Evidence From Overlap-Corrected Visual ERPs

Visual processing is influenced by spatial attention and prediction. Yet, in humans, it is still unclear if early sensory processing in the primary visual cortex (V1) is influenced by these top-down factors. To answer this question, various EEG studies have looked at the retinotopic C1 event-related potential (ERP), which arises from V1. Despite the fact that research on this question has been ongoing for more than two decades, discrepant findings have been reported. One reason for this heterogeneity could be due to the majority of studies focusing mostly on attention, without considering the possible role of prediction. Another reason could stem from the C1's specific sensitivities to stimulus features and individual differences. To address these issues, we developed a new paradigm that maximally utilizes the visual and spatial properties of the C1 and allows for the factorial manipulation of spatial attention and prediction. We also used gaze-contingent eye-tracking to confirm the use of peripheral vision to process the stimuli. Additionally, to account for the individual differences in the C1 response the experiment was tailored to each participant using an independent localizer. The ERP results showed a significantly smaller C1 amplitude in the upper visual field when attention was directed toward the peripheral stimulus as opposed to when it was directed away toward the center of the screen. After applying linear deconvolution to correct for temporal overlap between sequential ERP responses, this effect disappeared. We found that attention influenced the P1, while prediction mostly affected the P3. These novel results suggest that early sensory processing in V1 is not directly influenced by either attention or prediction; their effects are dissociable and mostly concern the P1 and P3 ERP components.