Drug and design
D-amphetamine (0.45 mg/kg, PO, Aspen Pharmacare, Australia) was used, giving a mean dosage of 33.7 mg based on the mean weight of the participants of 74.9 kg. Similar sizes and numbers of capsules containing either placebo (glucose) or 0.45 mg/kg d-amphetamine were prepared using 1, 2.5, 5, and 10 mg d-amphetamine sulfate tablets. This dose of d-amphetamine was selected based on previous experiments in healthy subjects demonstrating significant effects on a range of illusory and psychophysiological measures [