Log-transformed ERO theta power, representing frontal (F3, FZ, F4), central (C3, CZ, C4), and parietal (P3, PZ, P4) electrodes, was compared across genotypes using repeated measures analysis of variance (RM-ANOVA) of the general linear model (GLM) by using (i) the genotype (0, 1, 2) as between subjects factor, (ii) task condition (loss, gain) and region (frontal, central, parietal) as within-subjects factors, and (iii) ethnic stratification (PC1, PC2), age, gender, and family type as covariates in the model (see Table 2). RM-ANOVA results were extracted from the multivariate test statistics (O’Brien and Kaiser, 1985; Field, 1988) as the ERO data for the within-subjects factors did not adhere to sphericity assumptions (i.e., the equality of the variances of the differences between levels of the repeated measures factor such as region). In other words, an appropriate alternative for the sphericity assumption while analyzing the EEG data is to use multivariate tests within a repeated-measures design (Bell and Cuevas, 2012), as used in the current study. F-values and p-values of Pillai’s Trace (Pillai, 1955) were used. Further, on the figure illustrating the means of
