Data from 4 participants were dropped because they were extreme outliers on either stop RT or go RT (scores outside of 3 standard deviations). The demographic characteristics of this subsample (n = 89) were similar to those of the overall sample (see Table 2) and did not vary significantly across genotypic groups. In general, stop and go RTs were not related to demographic variables included in the study, although the go RT was positively correlated with caffeine use and negatively with BMI. Therefore, caffeine use and BMI were included as covariates in further analyses with go RT.
