Ten adult male squirrel monkeys (Saimiri sciureus) weighing 0.9-1.1 kg were housed in individual cages in a temperature- and humidity-controlled room with unrestricted access to water. Monkeys were fed five high-protein biscuits/day (Lab Diet 5045, PMI Nutrition International, Richmond, Indiana) and two pieces of Banana Softies (Bio-Serv, Frenchtown, NJ). Fresh fruits, vegetables and environmental enrichment were provided daily. Three monkeys (441, 431, 577) self-administered nicotine. Three monkeys (70F7, 5045, 39B) self-administered cocaine. Four monkeys (34A, 27B, 30A, 1549) were used for food -reinforcement experiments.
