Completed ratios for cigarette puffs (Figure 1a) and total responses made for cigarette puffs (Figure 1b) across the 3 doses of MPH for ADHD and non-ADHD participants. Error bars indicate SEM. Values represent means for each group under each condition. The ranges varied across dose conditions. For completed ratios, the ranges were 0 -6, 0-8, and 0-8 for the 0 mg , 10 mg, and 40 mg conditions, respectively. For responses made for puffs, the ranges were 0-4060, 0-8676, and 0-13701 for the 0 mg , 10 mg, and 40 mg conditions, respectively.