Allyson Bastien¹, Chanelle Demeule¹, Anthony Proulx¹, Caroline Blais¹, Daniel Fiset¹; ¹Université du Québec en Outaouais

Autism is a neurodevelopmental condition marked by difficulties in social communication and interaction (American Psychiatric Association, 2022). Face processing, in particular, is often impaired in Autistic individuals (Griffin et al., 2021). For instance, Autistic adults make limited use of the eye region and rely more on the mouth than neurotypical adults (Spezio et al., 2007). However, the neural mechanisms underlying these differences remain unclear. The present study sought to compare the brain’s electrophysiological response to faces in Autistic (n = 2 men) and neurotypical (n = 29; 12 men) adults. Brain activity was recorded using EEG while participants performed 2000 trials of a categorisation task (smiling or not smiling). Faces were partially revealed using the "Bubbles" method (randomly located Gaussian windows; Gosselin & Schyns, 2001). Classification images were used to reveal the pixels associated with EEG activity at electrode PO8 from -200 to 600 ms relative to stimulus presentation. Autistic and neurotypical subjects showed similar response patterns, both relying on the mouth to complete the task. In neurotypical subjects, 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. Findings revealed a greater complexity among Autistic participants. Participant A demonstrated a weak reaction to the eye region, despite a N170 latency similar to neurotypical subjects. In contrast, participant B exhibited a strong and particularly sustained reaction to the eyes and mouth, while showing a substantially delayed N170 relative to neurotypical participants. Increasing sample size would enable the identification of patterns, thereby facilitating a more precise understanding of the neural mechanisms underlying social difficulties in autism. These results demonstrate how the integration of two rigorous methods, EEG and "Bubbles", allows a deeper understanding of face processing specificities in autism.

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