Having seen Paravel and Castaing-Taylor’s other work, Crémieux, now chief executive for Marseille’s university hospitals, recognized that he had no idea what they would make. “Whatever the rational discussion could be at the beginning of the project, I knew that there would be no way of knowing in advance what the end of the project would be, which for a C.E.O. of a hospital is strictly different from the relationship we usually have with filmmakers and documentarists and TV people,” he said by Zoom.

But these are also public hospitals, and he felt that reputable anthropologists should have access to them. “I think that we owe that to the public, and we owe that to citizens,” he said. He also noted that forbidding access would have meant losing a chance to preserve what’s happening in hospitals today for future generations.

Doctors became active collaborators in the project, introducing Paravel and Castaing-Taylor to other physicians and patients, and even recommending procedures to capture, the filmmakers said. Some doctors, Castaing-Taylor added, were wary, not knowing whether to view the pair as scientists or journalists. “If they thought of us as scientists — because we said we’re not really journalists, we’re anthropologists — then they would want to know what our hypothesis was, what were we testing,” he said. “And as anthropologists, we’re not really scientists, even though some people think of anthropologists as scientists.” The goal wasn’t to test but to observe.

Jean Kolaczek — the retired chemist who has the screw turned in his head — was undergoing an operation to ease the pressure of liquid in his brain. He said that his surgeon introduced him to the filmmakers, and that his comfort with his doctor led him to say yes.

“I was interested in seeing the operation from the outside, too,” he said through an interpreter. “I was the sick person, I was the patient, but I was also interested in seeing what happens in the operating room and around it.” Even when he was awake in the scene, he pointed out, he was medicated and not completely conscious.