“It’s Only a Movie…”

"Naturally, the knife never touched the body; it was all done in the montage."
(Hitchcock talking to Truffaut about the shower scene in Psycho)

However, when analysed frame by frame, one of the short segments does appear to show a knife piercing Marion's flesh. It's only 8 frames in length (or 1/3 of a second) and the final frame is this:

At first glance, the knife does appear to have cut into the belly. However, I think the darkness we see on the left of the end of the blade is shadow (the light source is away to the left of the frame). In this image, the edge of the blade is highlighted in green, and it's shadow outlined in blue. What we're seeing is the tip of the blade against the skin.

The 7 previous frames show the knife swooping downwards quickly into the frame. How could they ensure the person holding the knife stopped in time to avoid stabbing Marion (it's not certain if we're seeing Janet Leigh's midriff or her body double, Marli Renfro)?

I've spent a good hour or so this evening watching those 8 frames over and over again…

I think the sequence was achieved quite simply — what we're seeing in the final film is reversed footage. What was actually shot begins with the knife held against the flesh, and then it's pulled away (up and out of frame).

Don't believe me? Then have a play with this web page which lets you run the sequence both ways at two different speeds.

There's 2 things which I think give it away:

• as the knife is pulled away, it leaves behind a steam of small water droplets
• the motion of the shower spray seems more "natural" in the version where the knife is pulled away

Also, on the final frame, I think we can see the impression on the skin of where the knife was resting.

Finally, the movement of the midriff again seems more natural when the frames are shown in reverse. As the knife is pulled back, Marion moves her body away.

Whilst we're on the subject of the shower scene, there is some obvious nudity as Marion's hand reaches out (presumably we're seeing Marli Renfro's breasts here)…

…and as Janet Leigh tumbles forwards, the moleskin she wore during filming is just visible across her chest for a single frame…

And just to wrap things up, here are a couple of magazine covers featuring Miss Renfro…

…Renfro was a professional glamour model who, according to those on set, was more than comfortable with being nude in front of the crew. Renfro certainly does appear in the sequence where Norman lifts Marion's body onto the shower curtain and a couple of the frames give away the fact that she was wearing underwear (visible on her hips)…