The equal probability Go/NoGo task design was aimed at controlling the possible ‘bias’ towards the “Go” response and other possible sources of variability as mentioned in the Introduction and Methods sections. The NoGo N2 “effect” was observed in both groups with the task used in the present study. Normal subjects showed significantly larger NoGo N2 amplitude compared to Go at frontal regions (Table 4, Figures 3a, b) that was further evident in the current density findings in the N2 time-range with sLORETA (Table 6, Figures 5a, b). These findings of the traditional NoGo N2 “effects” conform to previous studies that have used either the “reverse oddball” paradigm (e.g., Falkenstein et al., 1999; Kopp et al., 1996) or the “equal probability” paradigm (e.g., Lavric et al., 2004) or both (e.g., Jodo and Kayama, 1992; Nieuwenhuis et al., 2003). Although the alcoholic group did not show any significantly larger NoGo N2 amplitude than Go N2 at frontal regions (Table 4), when peak N2 amplitude values were taken as dependent measures, the sLORETA difference maps suggest significantly higher current density at the sources
