Methamphetamine
During three drug administration sessions, participants orally ingested, with water, a size 00 opaque capsule containing either 0 (placebo), 20 mg, or 40 mg of d-methamphetamine hydrochloride (Mylan, Inc.) and cellulose. Across sessions, the capsules appeared identical. Each participant received each condition once across her or his three sessions (i.e., dose conditions were compared within subject). Administration was double-blind, and dose order was counterbalanced.