Infants' Visual Preference for Upright Faces During the COVID-19 Pandemic in Japan.

The coronavirus disease 2019 (COVID-19) pandemic required face masks to be worn in public spaces, changing daily face-to-face communication. This study investigated whether infants perceived masked faces as faces during the COVID-19 pandemic, a time when wearing masks in public was nearly universal in Japan. Between July 2021 and November 2022, we conducted an experiment using a novel remote method to examine infants' preferences for upright versus inverted faces under both masked and unmasked conditions. Overall, infants aged 4-5 months and 7-8 months (n = 32 in each age group) preferred upright to inverted faces in both conditions. These results suggest that Japanese infants born during the COVID-19 pandemic could recognize masked faces as faces. Furthermore, across both age groups, the preference was more pronounced in the masked-face condition than in the unmasked-face condition. These results possibly reflect the fact that infants had relatively frequent exposure to masked faces during the pandemic.