William D. Davidson, 89, a psychiatrist whose specialties included the study of psychology, culture and human irrationality in international conflict resolutions, died May 11 at his home in Alexandria.

He had coronary artery disease, said his wife, Eliana Davidson.

Dr. Davidson was the founder and president of the privately funded Institute for Psychiatry and Foreign Affairs. The Washington-based organization, established in 1970, brought together diplomats, political leaders and military officials to discuss ways to bridge their differences.

Dr. Davidson held many other positions in psychiatry, particularly in the fields of international affairs and corrections. He was chairman and founder of the American Psychiatric Association’s Committee on Psychiatry and Foreign Affairs; a research psychiatrist for the Arms Control and Disarmament Agency at the State Department; and medical director of a center on violence and brain injury.

He was also a psychiatrist for the D.C. Department of Corrections and Virginia’s Staunton Correctional Center, and a clinical professor at the University of Virginia and George Washington University. He retired in 2000.

William David Davidson was born in Los Angeles and graduated from Duke University in 1947. He received a master’s degree in anthropology in 1948 and a medical degree in 1952, both from Duke.

He served in the Air Force Medical Corps and was a research fellow at Harvard Medical School before moving to the Washington area in 1968.

In the early 1970s, Dr. Davidson led a medical delegation to China. In 1976, he sailed across the Atlantic in a tall ship.

He was a member of the Cosmos Club.

His marriages to Florence Hickman and Carolyn Ashland Post ended in divorce. A son from his first marriage, Benedict Davidson, died in 1963.

Survivors include his wife of 30 years, Eliana Vilallonga Davidson of Alexandria; five children from his first marriage, Christopher Davidson of Bingen, Wash., John Davidson of Falmouth, Mass., Peter Davidson of Seattle, Bernard Davidson of Bellingham, Wash., and Miriam Davidson Cameron of Tucson; a daughter from his second marriage, Kirsten Davidson of Rockville; and nine grandchildren.

— Bart Barnes