Marshall Schlom, the Script Supervisor on Psycho, was interviewed on 30th November 2012:

“My job was to keep a record of the takes for editing. Hitchcock quit at 5.30pm every day. Even on location he would only stay until 7.00pm that was his maximum.

He became ill, and got the flu, so he asked me and Hilton to film the Arbogast sequence going up the stairs from the storyboards. He always wanted Hilton and me to have the same information as him on the set. So the two of us ended shooting those days he was ill. When it came to the Arbogast sequence, we showed him what we did, and the lights were dim, after the showing to him, we turned off the stop and go, he  went up to the screen turned around and put his hands behind him, and said fellows we’ve made a big mistake. George and I looked at each other, he said, when you show the hand on the rail, the feet on the stairs, this montage, this sequence, when you show it to the audience, you’re predicting, you’re telling the audience that something is about to happen, I don’t want that. Take them all out and give me a shot of Arbogast just coming in at the front door, point of view up the stairs, and then a shot of Arbogast coming up the stairs, put that in, and don’t put in anything else, because the audience is going to predict that something is going up. So we devised a way, camera floated and the hand came in right in front of that frame, and we cut to Arbogast going like this, so that’s what we have in the film.

Then we had a cast and crew screening of the film. When this shot came and the knife came in, everyone in the audience in front of us came off their seats this far, they knew the shot was coming in. In the dark, except for the flickering of the projection, he bent forward to look to me, and he smiled, that was his way of saying I told you this was going to happen.

Hitchcock had this other side of him, he kept poking away at this humour and everyone on the set responded to it. Jack Russell would line up the shot, and Hilton would get him from his dressing room.

I think he found Janet Leigh a bit stiff, I think she was a bit tense, I think she wanted to make sure that she did the right thing for Hitchcock. Very nice lady, very accessible. He occasionally went up to her and he’d tell her a dirty joke, and she started to laugh. She did soften because she had to stop laughing and that worked very well for her. The two worked very well, she was a joy to be around.

What was he really like? He had so many facets to his personality. I felt he was a pixie, a real pixie. On the one hand he could be one person, and the next moment he could be someone else. And if Janet started to laugh, he might have made her laugh even more.

One incident that happened, in the film there’s a shot of Vera Miles looking at a book and there’s a falcon bird way up in the frameline, and we did that shot for some reason several times. And it was like Hitchcock felt at that moment he wanted to get more of her reaction of what she was reading or what the audience would never see. Her eyebrow goes up a little and my recollection is that we had 10 or 12 shots of her with slightly different facial expressions at each time. Hitchcock said use the shot where her eyebrow goes up a little bit. We went back to the editing room but Hitch said that’s not the cut what I want, there’s another one. We must have followed these shots for an hour, looking for this eyebrow, but Hitch kept saying its still wrong, it’s not the one we want. Then we put all the shots on a reel and projected it on the screen, and he looked through, he said stop that’s the one I want. We couldn’t see it on the miovola it was too small, only when on the big screen. It was so minute that it was the only take he wanted. He never told us what’s in the book, but we’re assuming its pornography.

When he was directing films at Paramount, he had a favourite camera operator, and his name was Lenny South, and over a period of time, Lenny became a cinematographer, and I wouldn’t be surprised if Hitchcock helped him along some place.

Hitchcock knew everything about making movies, it was his job to go to work and make movies. I can tell you without a doubt, he knew more about making movies than any other director that I’ve been associated with. He ran a masterclass for me, that’s the best way to describe it.”