This clinical trial evaluates the effect of nicotine on eye movements and related behaviors in people who use electronic (e)-cigarettes. Nicotine is an addictive, poisonous chemical found in tobacco. It can also be made in the laboratory. When it enters the body, nicotine causes an increased heart rate and the use of oxygen by the heart and a sense of well-being and relaxation. E-cigarettes are the most commonly used tobacco products in young adults in the United States. E-cigarettes deliver nicotine rapidly and the potential for addiction (abuse liability) is comparable to combustible cigarettes. The Food and Drug Administration uses a combination of testing including self-reported scales, withdrawal assessments and behavioral tasks to evaluate the abuse liability of a nicotine product. Research has shown that nicotine alters movement of the eye (oculomotor) and the amount of nicotine in the blood impacts the extent of oculomotor function impairment. Despite this evidence linking nicotine to oculomotor changes, it has not been studied as a reliable marker for abuse in e-cigarette users. Studying eye movements can provide information about how the brain responds to nicotine and may help researchers develop better, more objective ways to measure how addictive nicotine products in e-cigarette users.