When Alfred Hitchcock’s “Psycho” opened on June 16, 1960, the subject matter was shocking. By today’s standards, the most shocking thing about the film was its distribution — a slow rollout that lasted for months, even though Paramount and Hitchcock wanted to maintain secrecy. When Robert Bloch’s novel was published in 1959, Hitchcock bought all copies to keep the plot twists under wraps. Similarly, studio execs and theater owners were given no details about the film.

“Psycho” opened on two Manhattan screens and in three other cities June 22. It bowed on 20 L.A. screens in August. These days, when viewers tweet film details during the first screening, months of secrecy would be unthinkable. But in 1960, most people cooperated. Hitchcock insisted no one be allowed to enter the theater after the movie started. His goal was to maintain suspense, but it became a marketing hook — and eventually became standard behavior for moviegoers.

In those days, moviegoers arrived at the theater whenever they wanted. If the movie was in progress, they would sit down and watch, then stick around for the next showing, to see what they’d missed.

Hitchcock wanted to prevent that. With “Psycho,” Anthony Perkins was top-billed, but Janet Leigh was the biggest star in the film. Hitchcock didn’t want audiences to enter during the second half and wonder “Where’s Janet Leigh?” the whole time. So he inaugurated the idea that audiences had to attend from the start of the film, which he said at a press conference was a “daring presentation policy.”

Bloch’s novel was inspired by Ed Gein, a real-life Wisconsin murderer in the 1950s, and details of his killings were too grisly to depict. The screenplay by Joseph Stefano made some major changes from Bloch’s book, including the expansion of Leigh’s character. Hitchcock wouldn’t give a script to Paramount execs, partly so they wouldn’t blab, and partly for fear they’d interfere with the touchy subject matter. Paramount reluctantly agreed to ask no questions, OK’ing a budget of $800,000.

The master of suspense,” as he was called, enlisted frequent collaborators like editor George Thomasini and composer Bernard Herrmann. For the cinematography, he signed John L. Russell, a veteran of his TV series who knew how to work quickly and cheaply.

To keep Par execs away, he filmed “Psycho” on the Universal lot, where his TV series “Alfred Hitchcock Presents” was based. (Film buffs are sometimes confused why the Universal Studios Tours takes people past the “Psycho” house and the Bates motel, though it was a Paramount film.)

The filmmaker’s secrecy paid off for him personally. In exchange for his unusual methods, Hitchcock gave up his usual salary — but got a huge backend deal. At the end of 1960, Variety estimated he would personally earn $6 million, stating that it was a showbiz record. That converts to about $50 million in current numbers.

At the end of 1960, Variety estimated that the film had earned $9 million in domestic rentals — that’s the portion of the box office that’s returned to the studio — and would probably earn that much overseas as well.

The film spawned three sequels, a 1998 Gus Van Sant remake, and A&E’s prequel TV series “The Bates Motel,” which just concluded after five seasons.