It is also important to note that low P3 is not unique to alcoholics and their high risk relatives, but is also found in individuals with one or more externalizing disorders or disinhibitory conditions (Carlson et al., 1999; Hill and Shen, 2002; Iacono et al., 2002; Iacono et al., 2003; Iacono and McGue, 2006; Patrick et al., 2006; Carlson et al., 2007; Hicks et al., 2007; Iacono et al., 2008; Patrick, 2008; Gilmore et al., 2010a; Gilmore et al., 2010b, 2012). As reported by several studies, an underlying feature among risk propensity, externalizing disorders and alcoholism is the concept of “impulsivity”, which is a conglomerate of personality traits that can result in premature, unduly risky and poorly conceived actions, and is known to be closely related to disinhibitory traits and clinical vulnerability (Gorenstein and Newman, 1980; Martin et al., 1994; Olson et al., 1999; Krueger and Piasecki, 2002; Hall et al., 2007; Kamarajan et al., 2007; Crews and Boettiger, 2009; Romer et al., 2009). Interestingly, P3 amplitude has been found to be either negatively correlated with impulsivity or lower in
