De Havilland was praised for her performance as Virginia Cunningham in Anatole Litvak's drama "The Snake Pit" (1948), one of the first films to attempt a realistic portrayal of mental illness and an important exposé of the harsh conditions in state mental hospitals, according to film critic Philip French. Based on a novel by Mary Jane Ward and produced by Darryl F. Zanuck, the film is about a woman placed in a mental institution by her husband to help her recover from a nervous breakdown. Virginia Cunningham was one of the most difficult of all her film roles, requiring significant preparation both mentally and physicallyshe deliberately lost weight to help create her gaunt appearance on screen. She consulted regularly with psychiatrists hired as consultants for the film, and visited Camarillo State Mental Hospital to research her role and observe the patients. The extreme physical discomfort of the hydrotherapy and simulated electric shock therapy scenes were especially challenging for the slight actress. In her performance, she conveyed her mental anguish by physically transforming her face with furrowed brow, wild staring eyes, and grimacing mouth.