Figure 1. Schematic overview of experimental design.

Note. Bev. Admin. Stands for beverage administration. Baseline sessions (3–4 hr) were held between 9am and 1pm. Experimental sessions (4 hr) were held between 12pm and 5pm. Sessions were held 1–3 weeks apart. Baseline Session: after BrAC testing to confirm sobriety, participants provided informed consent and completed the three WM Updating tasks (Letter Memory [LM], Keep Track [KT], and Spatial N-Back [SNB]; squares labeled ‘1’, ‘2’, ‘3’) and six other EF tasks (rectangle labeled ‘…’; not reported here). Tasks were completed in a fixed order counterbalanced across participants. Experimental Session: After BrAC testing to confirm sobriety, participants provided informed consent again and were asked to void the bladder, during which time, female participants also self-administered a hormone-based (urine) pregnancy test in a private restroom (all tested negative). Participants were then administered a beverage and completed the three WM Updating tasks (LM, KT, SNB; squares labeled ‘1’, ‘2’, ‘3’) and two other EF tasks (squares labeled ‘…’; not reported here) once or twice during the session according to randomly assigned experimental conditions. Participants were randomly assigned to one of six experimental cells resulting from fully crossing a 3-level beverage condition with a 2-level assessment condition. Beverage conditions were alcohol (0.80 g/kg for males, 0.72 g/kg for females), active placebo alcohol (0.04 g/kg), and no-alcohol control (tonic only). Participants assigned to the control condition were told that the beverage contained “no alcohol” whereas participants in the alcohol and placebo conditions were told that the beverage contained “a moderate amount of alcohol.” Assessment conditions were A/D (tasks completed during both ascending and descending limbs of the BAC timecourse or corresponding timepoints) and D-Only (tasks completed only during descending limb of the BAC timecourse or corresponding timepoints). Following beverage administration, participants assigned to the A/D condition completed the tasks when BrAC had risen to at least .065 g% (or corresponding timepoints) whereas participants assigned to the D-Only condition watched episodes of a popular sitcom (The Office [U.S.]). After peak BrAC (≈0.085 g%), participants in both the A/D and D-Only conditions completed the tasks (in reverse order) when BrAC had fallen to at least 0.075 g% (or corresponding timepoints).