Of the five TF components extracted in the present study, two delta components were able to independently discriminate group membership, accounting for an increment in variance over that accounted for by P3 amplitude: PC2 for the ADHD and alcohol groups, PC3 across all diagnostic groups (just short of significance for the small DAD group). Further, these two components were associated with a common factor representing the shared variance among symptom counts of all disorders. PC2 corresponds closest in time to the P3b wave typically found in response to targets in the oddball task. PC3 spans the time range of the P2-N2-P3 ERP complex (and is significantly correlated with P2 amplitude, r=.53, p<.001, and the microvolt value associated with the trough of the N2 wave, r=.39, p<.001). PC3, then, may be most representative of the specific activity indexing signal matching, decision-making, and salience detection processes previously attributed to P3-related delta activity generally (Basar-Eroglu et al., 1992; Karakas et al., 2000; Knyazev, 2007). These cognitive processes have been implicated in ADHD, conduct disorder, and substance use disorders (Dom, De Wilde, Hulstijn, van
