The purpose of this study is to obtain a database of brain function from a sample of non-smokers while they do tasks in an MRI (magnetic resonance imaging) machine. Our hypothesis is that among nonsmokers, reactivity to smoking cues will be highly similar to control cues but may vary as a function of attitudes toward smoking and/or family history of smoking. We also hypothesize that brain activity during the n-back task will be more similar to data collected during this task when smokers are not abstinent.