Results of the mixed model ANOVA have been tabulated in Table 2. Group as a main effect was not significant. Main effects of Valence, Amount and Region were significant. Gain condition as well as large amount (50) had higher amplitude and shorter latencies than Loss condition and small amount (10), respectively. Frontal, central and parietal areas had higher amplitudes and shorter latencies than occipital, left temporal and right temporal areas. Group × Outcome interaction was significant in all four measures while Group × Amount interaction was significant only for the amplitudes of ORN and ORP. Group × Valence × Region was significant only for the ORN measures, and the Group × Amount × Region was not significant in any of the ERP measures. Pairwise comparisons were done to explain these findings (see Figs. 7 and 8). Comparisons of ORN and ORP amplitudes across groups in each outcome condition at different electrode sites are illustrated in Fig. 7 along with Bonferroni adjusted significance levels. Alcoholics showed significantly lower ORP amplitude during all outcome conditions and decreased ORN amplitude during loss conditions (−50 and −10). Latencies showed no group differences (not shown).
