 The investigators hypothesize that African Americans AAs smoke more for positive reinforcement from nicotine with a peak-seeking pattern of smoking smoking individual cigarettes more intensively with greater intake of nicotine and tobacco smoke toxins, while whites smoke more for negative reinforcement with a trough-maintaining pattern avoiding withdrawal by maintaining more consistent nicotine levels throughout the day by means of a more regular smoking pattern. The investigators believe that these patterns are linked to identifiable racial differences in nicotine pharmacology and that there will be associated racial differences in responses to pharmacologic interventions. 