The most robust association has been found between externalizing disorders and the P3 ERP. P3 is elicited by detection of a stimulus that deviates from the ongoing context of the task, and it is theorized to reflect context updating in working memory and the generation of subjective expectancies related to the probability of target occurrence (Donchin & Coles, 1988; Duncan-Johnson & Donchin, 1977; Soltani & Knight, 2000). Reduced peak amplitude of the P3 has long been associated with alcoholism and familial risk of developing alcoholism (Begleiter et al., 1984; Hill, 2004; Hill et al., 1995; Polich, Pollock, & Bloom, 1994). Recent work, however, has expanded P3 amplitude reduction’s (P3-AR’s) association to other EXT spectrum disorders (e.g. Iacono et al., 2002), as well as to the underlying EXT factor (Patrick et al., 2006) – an association that is accounted for by shared genetic effects (Hicks et al., 2007).
