 Objective: The primary objective of this study is to investigate the dose-related effects of nicotine on various elements of attention in smokers and nonsmokers. Because no published study, to our knowledge, has reported the effects of nicotine on the ANT and ABT, we will include the CPT, a task shown to be sensitive to nicotine, as a positive control. A secondary aim is to compare the subjective and physiological effects of nicotine between smokers and nonsmokers. 