Volunteers will be asked to live on a research unit for up to twenty-six (26) consecutive nights and will participate in a total of 38 study sessions held on 19 weekdays. Each session will last approximately four hours and there will be two sessions per day, therefore each study day will last approximately eight hours. In addition to these study sessions, an orientation session will be conducted on the Friday prior to admission to the inpatient unit, and a lottery session will be held on the last day of the study.

During each study session participants will be asked to smoke a cigarette. The cigarette may contain marijuana or it may contain placebo (a blank). Participants will also be asked to swallow a capsule 2-hours prior to smoking the cigarette. The capsule could contain placebo (a blank), THC (delta-9 tetrahydrocannabinol, which is the active ingredient in marijuana responsible for its mood effects), or d-amphetamine. We will have participants answer questions about how the drugs make them feel and measure their vitals signs (blood pressure, heart rate, and oxygen saturation) will be measured using a non-invasive (external) vitals monitor.