Although alcohol use may be characterized in various ways (including frequency of use, age of first use, and various measures of consumption quantity), most other studies restrict alcohol-use measures to indices of consumption quantity (e.g., amount of alcohol consumed in the previous year; maximum amount of alcohol consumed on one occasion), or combine indices of consumption quantity and frequency of use into a single measure (Carlson et al., 2002; Perlman et al., 2009). Emphasis on consumption quantity as a primary index of alcohol use is likely due to the observation that quantity, rather than frequency of use, generally has a larger effect on the P300 (Neville and Schmidt, 1985; Polich, 1984). The observed significant association between P3b amplitude and regular drinking frequency is therefore (a) difficult to contextualize in relation to the literature because frequency of use is rarely examined as an independent measure, and (b) difficult to explain since neither measure of consumption quantity was associated with the P300. Furthermore, the significant association relating to frequency of use alongside the absence of any significant association with consumption quantity is
