Stimuli and methods of data collection and processing for event related potentials have been described in previous studies of the Visual Oddball Paradigm in COGA (Cohen et al., 1994; Porjesz & Begleiter, 1998). Consistent with previous studies using COGA data, the current study examined peak amplitude, relative to the pre-stimulus baseline, of P3 to target stimuli in the 250–600 ms time window at the Pz (midline parietal) electrode. This task and task parameters were chosen due to the large, existing body of literature linking P3 response under these conditions and externalizing liability (Gilmore et al., 2010; Iacono & Malone, 2011; Porjesz et al., 2005). If individuals had full data including P3 data from more than one timepoint, the P3 amplitude from their last (oldest age) data collection and matched self-report data were used.
