Fifty-four smokers (≥10 cigarettes per day for ≥6 months) gave written informed consent as approved by the University of Pennsylvania institutional review board. Subjects were required to be 18 to 65 years of age and right-handed, with no history of brain trauma or DSM-IV Axis I psychiatric disorders or substance (except nicotine) dependence.23 Exclusion criteria consisted of use of other tobacco or cessation products, pregnancy, and IQ scores of less than 90 on the Shipley Institute of Living Scale.24
