Casey Becker¹, Mary Kate Richey¹, Arish Alreja¹, Jorge Gonzalez-Martinez¹, J Patrick Mayo¹, Avniel Ghuman¹; ¹University of Pittsburgh

Faces rarely appear suddenly in our central vision (fovea); instead, specialised neural systems detect faces in our periphery and direct our attention towards them. The blurry parafoveal preview of a face recruits prediction mechanisms that update when the fixation lands on the target face. And yet, much of what we know about the neuroscience of face perception relies on paradigms where faces are presented abruptly at central fixation, overlooking the dynamic role of eye movements in natural vision. Here, we examine the role of the parafoveal preview on faces and houses, using high-speed eye-tracking and intracranial EEG (depth electrodes). In a gaze-contingent paradigm, we compared traditional centrally presented faces and houses with parafoveally presented ones. Participants freely looked towards faces, houses, or blank squares that appeared in their parafovea. Parafoveal faces and houses could remain the same (valid preview), turn into blank squares (face-to-blank), or vice versa (blank-to-face). As expected, neural activity from faces that suddenly appear in the fovea differs from activity induced by previewing. This did not greatly differ between centrally presented faces and those that appeared during a saccade towards a blank square, suggesting similarity between central onset and an invalid preview. Interestingly, when an object disappears during a saccade, responses are similar to valid previews, suggesting much processing occurs before fixation. Responses to faces, but not houses, somewhat differ when the stimulus disappears during saccade, suggesting differences in predictive processing.