Schedule Each participant completed two consecutive test days per week for three consecutive weeks. At the start of test days, which occurred at the same time each day, participants answered open-ended questions regarding sleep, medication use, eating behavior, selleck chem FTY720 and health status during the preceding 24 hr and completed field sobriety, breath (Alcohol Sensor III, Intoximeters, Inc.; piCO Carbon Monoxide Monitor, Bedfont Scientific), and urine tests (cocaine, benzodiazepine, barbiturate, marijuana, amphetamine, and opiate drug use using OnTrak TesTstik, Varian, Inc.; pregnancy using Clearview HCG II, Unipath, Ltd). Thirty-minute sessions were completed on Day 1 following ad libitum smoking, on Day 2 following 24 hr of tobacco deprivation, as verified by breath (CO levels �� 10 ppm were required to complete Day 2 testing), and then repeated on Day 2 following paced smoking of eight puffs from one experimental cigarette.

The paced smoking procedure was adapted from Kelly, Foltin, Rose, Fischman, and Brady (1990) and consisted of a 3-s preparation interval, a 3-s inhalation interval, and a 14-s exhale and rest period. This procedure was repeated eight times for each experimental cigarette. Following the postsmoking session, additional experimental cigarettes containing the nicotine yield administered that day could be self-administered for 2 hr. All cigarettes were smoked using a mouthpiece connected at the front and rear with PVC tubing to a volumetric transducer. The flow of air through the mouthpiece was measured to determine the duration and volume of each puff.

Upon completion of testing each week, subjects received $60. Upon successful completion of all three 2-day testing occasions, subjects received an additional $180 bonus plus task performance earnings. Total earnings were approximately $365; there were no group differences in earnings. Drug Commercially available cigarettes delivering 0.05 (Quest? Step 3), 0.6 (Quest? Step 1), and 0.9 mg (Kent?) of nicotine were prepared with black tape covering the brand name, so that all cigarettes looked the same, regardless of nicotine content. Doses (i.e., nicotine yield) were administered in a randomized order across the 3 weeks of the study. Session Measures During each session, self-report questionnaires (e.g., Foltin & Fischman, 1991), psychomotor and cognitive tasks (e.g.

, Roache, 1991), and cardiovascular measures were completed in the following order. Wisconsin Smoking Withdrawal Scale This 28-item questionnaire yields ratings Batimastat on seven subscales: anger, anxiety, concentration, craving, hunger, sadness, and sleep on scales from 0 to 4. Each item was rated along a 5-point scale, from ��Strongly disagree�� to ��Strongly agree.�� This scale was used to assess the global effects of tobacco withdrawal (Welsch et al., 1999).