A significant three-way interaction indicated that higher impulsivity was associated with weaker sedative response (Table 2). We based this conclusion on examination of plots of sedative response among the most and least impulsive participants (Figure 2). These results were found while holding other variables constant: family history, gender and test day (Table 2). After examination of the plots, we again fit additional nonparametric models to assess changes between timepoints during ethanol infusion. These findings paralleled results for stimulant response but in the opposing direction. In a model examining change between the +10 and +30 timepoints, the three-way interaction was significant (num df = 1.82, ATS = 4.48, p = 0.014). While differences were not observable at the +10 timepoint, the increase in sedation between the +10 and +30 timepoints was greater at lower impulsivity levels. As with stimulant response, this change was most pronounced during high-dose ethanol administration (Figure 2). In a model to assess change between the +30 and +60 timepoints, also paralleling the simulant results, the dose by impulsivity interaction was significant (num df = 1.99, ATS =
