The shower scene in Alfred Hitchcock’s “Psycho” is one of the most familiar in film history, and in his new documentary “78/52,” the director Alexandre O. Philippe examines the sequence in myriad ways.

“There’s so much I’m still discovering. That’s why people keep going back to it, because it goes so deep,” he said.

Think you know “Psycho”? Here are five things about the scene that might surprise you:

1. The story was adapted from a 1959 novel of the same name by Robert Bloch. But the killing is a lot shorter in the original telling.

Hitchcock took 78 shots and 52 cuts (hence the documentary’s title) to capture Marion’s murder. Bloch took only 2 1/2 sentences to describe the killing, which ends with Norman lopping off Marion’s head.

2. To make an accurate stabbing sound, Hitchcock listened as his prop man hacked away at a variety of melons. Which sounded most like flesh being cut by a knife? Hitch’s determination: casaba. Philippe collected 27 melon varieties from Latin America, Asia and Europe, chopped into them and sent sound files to Skywalker Sound.

Their conclusion: casaba.

“It has a very thick skin, and it’s gooey in the center,” Philippe said.

3. In addition to stuffed birds , the motel parlor displayed a reproduction of “Susanna and the Elders,” by Frans van Mieris the Elder, in which two old men leer at a woman as she bathes.

In “Psycho,” Norman uses “Susanna” to cover the peephole through which he spies on Marion.

4. Martin Scorsese used the shower scene as a model for the bout between Jake LaMotta and Sugar Ray Robinson in “Raging Bull,” when Robinson raises his right arm high above his head before smashing in LaMotta’s face.

5. Body double Margo Epper, not Anthony Perkins, played Norman in the stabbing scene. Perkins was in New York rehearsing for a Broadway show, so Epper donned Norman’s unbecoming dress and wig for the climactic scene.