The effects of Covid-19 related policies on neurocognitive face processing in the first four years of life

In response to Covid-19, western governments introduced policies that likely resulted in a reduced variety of facial input. This study investigated how this affected neural representations of face processing: speed of face processing; face categorization (differentiating faces from houses); and emotional face processing (differentiating happy, fearful, and neutral expressions), in infants (five or ten months old) and children (three years old). We compared participants tested before (total N = 462) versus during (total N = 473) the pandemic-related policies, and used electroencephalography to record brain activity. Event Related Potentials showed faster face processing in three-year-olds but not in infants during the policies. However, there were no meaningful differences between the two Covid-groups regarding face categorization, indicating that this fundamental process is resilient despite the reduced variety of input. In contrast, the processing of facial emotions was affected: across ages, while pre-pandemic children showed differential activity, during-pandemic children did not neurocognitively differentiate between happy and fearful expressions. This effect was primarily attributed to a reduced amplitude in response to happy faces. Given that these findings were present only in the later neural components (P400 and Nc), this suggests that post-pandemic children have a reduced familiarity or attention towards happy facial expressions.