P3 amplitude was highly correlated between the three sites (r=0.87 for Pz-P3 and Pz-P4), as well as between the easy and hard target conditions (r=0.89). Further, previous analyses have shown that associations between P3 amplitude and the externalizing factor do not differ as a function of these three electrode sites (Hicks et al., 2007; Patrick et al., 2006). Therefore, to simplify presentation, current analyses were performed on ERPs only from the Pz electrode and averaged over easy/hard target conditions.
