Received Aug. 7, 2001; revisions received Feb. 1 and May 30, 2002; accepted June 6, 2002. From the Department of Psychology, Göteborg University; Department of Neuroscience, Unit of Pharmacology, Uppsala University, Uppsala, Sweden; and the Laboratories of Comparative Ethology and Clinical Studies-Primate Unit, National Institutes of Health Animal Center, Poolesville, Md. Address reprint requests to Dr. Fahlke, Department of Psychology, Göteborg University, P.O. Box 500, SE-405 30 Göteborg, Sweden; Claudia.Fahlke@psy.gu.se (e-mail). Supported by intramural research funding from the National Institute on Alcohol Abuse and Alcoholism, the National Institute of Child Health and Human Development, the Swedish Medical Research Council (13447 and 4145), the Söderström-Königska Foundation, the Swedish Brain Foundation, and the Swedish Alcohol Monopoly Foundation for Alcohol Research (00/4:2). The authors thank Graham Flory, Ann Hurley, Stephen Lindell, Judy Pushkas, Sigrid Sandberg, Courtney Shannon, Tom Tsai, Kathy Weld, and Kristin Zajicek for technical assistance.