However, other studies showed slightly different findings: A study of 6- and 7.5-month-old infants found a greater PSW amplitude at right temporal and midline frontal regions when viewing pictures of novel as compared to familiar objects (Reynolds, Guy & Zhang 2010); another study of 6-month-olds

showed no difference in PSW amplitude between hemispheres when viewing pictures of both familiar Metabolism inhibitor and unfamiliar faces (de Haan & Nelson, 1999); a third study of 6-month-olds demonstrated a PSW localized only over the right hemisphere when viewing upright faces (de Haan et al., 2003). Thus, there remains some controversy surrounding regional localization of the PSW during face processing, and future work should continue to explore these hemispheric differences.

In the ERP analyses focused on frontocentral electrode sites, the present study found no influence of group or condition on Nc and PSW amplitude. On the other hand, ERP analyses focused on temporal sites revealed several significant findings relating to both group and condition for both components. Mean amplitude for Nc was similar for the VPC, recent familiar, and novel face for CON, but in contrast, HII showed a diminished Nc response to the recent familiar face as compared to the VPC face. With greater GSK3235025 mouse Nc thought to reflect greater attention (Nelson & McCleery, 2008), this suggests that HII might devote less attentional processing to the recent familiar face, the face they were familiarized to just before the ERP session, as compared to the VPC face. This diminished attention in relation to other

stimuli in HII as compared to the consistent attention across conditions in CON necessitates further study, but suggests an atypical pattern of attention to familiar and unfamiliar stimuli in the HII group. Positive slow wave analyses over temporal electrode sites revealed a main effect of condition, with greater responses to recent familiar as compared with VPC and novel faces. Past work has identified a role for the PSW in memory updating (Nelson & McCleery, 2008), and the larger PSW in the present analysis could Farnesyltransferase reflect that the recent familiar face is the most remembered face for these 12-month-olds. This finding is consistent with the current VPC findings, as on Day 2, neither HII nor CON show a novelty preference during the VPC, suggesting that their memory for the VPC face was not strong on Day 2, the day of ERP testing. Thus, infants might show the greatest PSW to the recent familiar face while treating the VPC and novel face as new and not remembered. On a group level, both HII and CON showed greater PSW responding to the recent familiar face as compared to the VPC face, but this difference was more pronounced for HII.