The fact that ERN amplitude was larger in the placebo than in the control condition suggests a sensitivity of evaluative control processes to expectancy-related effects. Previous researchers have reported effects consistent with the idea that participants who consume placebos attempt to compensate for anticipated alcohol-induced impairment of cognitive and motor responses (e.g., Fillmore, Mulvihill, & Vogel-Sprott, 1994; Fillmore & Vogel-Sprott, 1995; Saults, Cowan, Sher, & Moreno, 2007; Williams, Goldman, & Williams, 1981). If so, making errors could be particularly frustrating or distressing—especially if participants are concerned about the implications of responses that could reveal race bias—thereby eliciting larger ERNs. An important consideration for future research will be further specifying the extent to which differences in ERN amplitude and posterror adjustment after alcohol versus placebo consumption are attributable to a combination of the anxiolytic effects of alcohol and expectancy effects associated with placebo consumption, as well as individual differences in preexisting expectancies concerning cognitive impairment (e.g., Fillmore & Blackburn, 2002).
