During the following three test days (2-4) before dispensing study drug, male participants who qualify, will be asked to fill out a questionnaire about tobacco or nicotine use since their previous visit along with assessing any change in their medications (specifically verifying that a male participant has not used an allergy, cold/flu medication within 3 days of their study visit). If the participant answers yes to either question, they will be asked to return to the clinic on a different day: 1) 3 or more days post using an antihistamine or 2) at least 2 weeks post using tobacco or nicotine. Both antihistamine medications or tobacco/nicotine recent use can effect a participant's PPI which is why we have the need to ask male participants about any possible changes. They will also be asked how they arrived to the clinic to verify that they have a driver who came with them/dropped them off, had a hired driver provided by the study if they live in Durham or came by bus or by foot. They will be asked about their caffeine use on the day of their experiment. Their baseline sedation level will be assessed. On test days 2-4, the test procedure employed on test day 1 will be repeated, but 60 minutes before the start of each test sessions, participants will receive a placebo, a low (12.5 mg) dose of meclizine, or a high (25 mg) dose of this drug in a counterbalanced order.