A large body of evidence suggests that alcoholics process stimuli differently from non-alcoholics, and that electrophysiological measures of stimulus processing discriminate groups of alcoholics from non-alcoholics and groups of individuals at high risk of developing alcoholism from groups not at high risk. One of the most robust findings in electrophysiological alcoholism research is the reduction in the amplitude of the P3b ERP component in alcoholics and in high risk individuals (1984; Begleiter et al., 1987; Benegal et al., 1995; Berman et al., 1993; Cohen et al., 1997; Ehlers et al., 2003; Fein and Chang, 2006; Glenn et al., 1994; Glenn et al., 1996; Hill and Steinhauer, 1993; Iacono et al., 2003; Kamarajan et al., 2005; O’Connor et al., 1986; O’Connor et al., 1987; Polich et al., 1994; Porjesz and Begleiter, 1985; 1990; Porjesz et al., 1998; Steinhauer and Hill, 1993; Suresh et al., 2003; Van der Stelt et al., 1998). The P3b is a subcategory of the P300, and occurs when an individual attends or responds to an infrequent but task-relevant target stimulus. It is defined as a centro-parietal positive voltage peak in the ERP waveform occurring between 300 to 500 milliseconds after stimulus presentation.
