Womack and his staff for organizational support. To Drs. Neil R. Burch, James 1. Claghorn, Beng T. Ho, Robert ]. Johnson, and Joseph c. Schoolar, heads of Institute research departments, thanks for their contribution in chairing symposium sessions. To Lore Feldman, who claims all typographical errors, credit for skillful copy editing of the manuscript. Typesetting was done by Gee Lindblom of the medical illustration and audiovisual education department at Baylor College of Medicine. Charles M. Gaitz v Contributors Paul E. Baer, Ph. D. Professor, Departnwnt of Psychiatry, Baylor College of Medicine, Houston, Texas Arthur L. Benton, Ph. D. Professor of Neurology and Psychology, University of Iowa, Iowa City, Iowa James E. Birren, Ph. D. Director, Gerontology Center, University of Southern California, Los Angeles, California Ewald W. Busse, M.D.