Chanelle Demeule¹ (), Anthony Proulx¹, Justin Duncan², Caroline Blais¹, Daniel Fiset¹; ¹Université du Québec en Outaouais, ²Ottawa University

Previous studies suggest that early perceptual brain activity in face recognition (N170) is linked both to the processing of the eye region and to the processing of diagnostic information (i.e., task-relevant; Schyns et al., 2007; Smith et al., 2004). However, in such previous studies, eye information and diagnostic information were confounded - that is, the eyes conveyed diagnostic information. The present study aimed to disentangle the two by creating facial stimuli where the eye region was completely identical between the two versions of the same identity (smiling or neutral). This will allow us to precisely measure the role of the eye region in the occurrence of the N170. We recorded brain activity using EEG for 29 participants (12 men, 17 women) while they categorized the expressivity of faces. On each trial, Faces were revealed only partially through randomly located Gaussian apertures (“Bubbles”; Gosselin & Schyns, 2001). Using time-resolved classification image techniques, we were then able to reveal image pixels that were associated with brain activity at PO8, from -200ms to 800ms post-stimulus, on a subject basis. A pixel test (p<.05; Stat4Ci Toolbox; Chauvin et al., 2005) revealed a significant association between N170 amplitude and the contralateral eye, the ipsilateral eye and the mouth. These results add credibility to the theory that the N170 reflects both a sensitivity to the eye region, independent of task demands, and the integration of goal-oriented information.

Acknowledgements: The present study is supported by the Natural Sciences and Engineering Research Council of Canada to Daniel Fiset (#RGPIN-2022-04350)