He later attended Yale School of Medicine and ultimately became Professor of Psychiatry at Yale until 1966 when he left Yale to become Chairman of the Psychiatry department at the University of Chicago where he continued his psychopharmaceutical research, primarily concerned with 5-hydroxytryptamine (serotonin).
He was a Professor of Psychiatry at Yale until 1966 when he transitioned to the University of Chicago as Chairman of their Psychiatry department. His research centered around psychopharmaceutical studies, specifically focusing on 5-hydroxytryptamine (serotonin).