He threw live birds at her for 3 days to film the attic scene. She had a nervous breakdown. He made her film anyway. That completely zoned out thing she did at the end of the movie, that wasn’t acting, that’s what was left of her sanity.
He was a brilliant director, but she’s by no means the first person to point out that he was willing to be extremely abusive to get what he wanted, both on and off camera.
I don’t have any details, but I remember that Vera Miles was supposedly close to a breakdown while filming The Wrong Man. Kim Novak said she was put through the wringer filming Vertigo. I think. It’s been a while since I was reading about that era of film.
I heard he had her down a silver mine and tried to drown her.