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.