Investigating the role of visual experience with face-masks in face recognition during COVID-19

The introduction of face masks during COVID-19 presents a potential challenge for human face perception and recognition. Face masks possibly hinder the holistic processing of faces leading to difficulty in facial recognition. Our present study aims to investigate this issue by probing the neuropsychological mechanisms of face recognition, while also exploring a possible learning effect observed in regularly seen (personally familiar) masked faces. Our stimuli consisted of personally familiar, famous, and unfamiliar Indian faces in masked and unmasked conditions. Subjects participated in a 2-back task wherein trials were balanced within and across blocks to represent all conditions identically, while behavioral and EEG responses were recorded. Statistical analyses revealed significant main effects of familiarity and mask-conditions on performance accuracy and reaction time (RT). The highest performance accuracy was observed for familiar and unmasked faces and the least for unfamiliar and masked ones, whereas RTs followed expected reverse trends. Notably, the difference in performance accuracy between unmasked and masked famous faces was more prominent than that for personally familiar faces. These observations are suggestive of a beneficial effect of visual experience found for frequently seen masked faces. Masked unfamiliar faces contributed to the highest proportion of false-positive errors, indicating the inherent difficulty in processing novel masked faces compared to known ones. EEG analysis revealed effect of face masks on N250 for both famous and personally familiar faces and N170 for only personally familiar faces. Our study suggests that personal familiarity aids perceptual learning of masked faces, and this learning may not generalize across familiarity levels.