Rebecca M. Todd, Marc D. Lewis, Liesel-Ann Meusel, Philip David Zelazo

To date, little is known about the neural underpinnings of social-emotional  processes in young children. The present study investigated the time
course  of children’s ERP responses to facial expression and personal familiarity, and  the effect of these variables on ERP measures of effortful
attention in a  Go-Nogo task. Dense-array EEG was collected from 48 4–6-year-old children who  were presented with pictures of their mothers’
and strangers’ happy and angry  faces. ERPs were scored following face presentation and following a subsequent  cue signaling a Go or Nogo
response. Responses to face presentation showed  early perceptual components that were larger following strangers' faces,  suggesting facilitated
rapid processing of personally important faces. A  mid-latency frontocentral negativity was greatest following angry mothers’  faces, indicating
increased attentional monitoring and/or recognition memory  evoked by an angry parent. Finally a right-lateralized late positive component  was
largest following angry faces, suggesting extended processing of  negatively valenced social stimuli in general. Following the Go-Nogo response cu  e,
a right-lateralized mid-latency negativity thought to measure effortful  attention was larger in Nogo than Go trials, and following angry than  happy
faces, possibly reflecting increased effortful control required in  those conditions. The present study suggests that overlapping but  differentiated
networks for both rapid and elaborative processing of  important socio-affective information are established by 4–6 years. Moreover,  the extended
spatial and temporal distribution of components suggests a  pattern of response to social stimuli in which more rapid processes may index  personal
familiarity, whereas temporally extended processes are sensitive to  affective valence on both familiar and unfamiliar faces.