Outcome Measures. This study involves assessing neurophysiological and behavior differences between cohorts (smokers vs. non-smokers) and conditions (nicotine vs. placebo-patch; baseline vs. varenicline vs. placebo-pill). The primary outcome measures used to ascertain these differences will be: 1) percentage change in fMRI BOLD signal during performance of cognitive control and reward processing tasks; 2) change in ERP component (e.g., error-related negativity) amplitudes; 3) behavioral measures during task performance including reaction times and error rates; 4) scores on mood, personality, and smoking questionnaires; and 5) variations in genes related to nicotinic receptors and DA functioning.