Subjects (schizophrenia patients and healthy control smokers) must be between the ages of 18-50 and in good health based on history and physical exams. Age restrictions are based on age-related declines (usually occurring after age 55-58) in eye tracking performance. Schizophrenia patients are persons with a DSM-IV Axis-I diagnosis for schizophrenia, based on a best-estimate diagnosis by the Structured Clinical Interview for DSM-IV (SCID) supplemented by family informants and medical records, done at the MPRC. Those in nicotine protocols must demonstrate that they are experienced users based upon exhaled CO and must smoke a minimum of 10 cigarettes/day with duration of use of at least 1 year. Subjects may be users of alcohol and/or marijuana but may not meet criteria for dependence on either and may not have used either for at least 24 hours prior to scanning.