It was that moment — among other dark, disturbing images (think: sacrifice victim burned alive) in the second installment of the Steven Spielberg and George Lucas adventure series — that upset parents, who felt the film's PG rating from the Motion Picture Association of America was too lenient. Due to the outcry, Spielberg decided there needed to be an interval between PG and R.

There's a fascinating backstory to the birth of the PG-13 rating, and its worth recalling on the anniversary of Temple of Doom's 1984 release Tuesday.

That year, the MPAA decided an R rating would be too harsh for Indiana Jones and the Temple of Doom, even though the film's tones and imagery were far more disturbing than the 1981 Harrison Ford starrer that kicked off the series, the child-beloved Raiders of the Lost Ark. So, Temple received a PG and was released May 23, 1984.

Parents were irate, and Spielberg and then MPAA president and ratings creator, the late Jack Valenti , heard about it.

“As a parent, I think the most important guide are those ratings,” Spielberg said in an MPAA video (For All Audiences: The Film Ratings System) created in 2008 to mark the 40th anniversary of the ratings system.

There was also an uproar over Gremlins, which came out in June 1984. Spielberg was an executive producer on that film about a cute little pet creature called a Mogwai that unintentionally spawns vicious, violent monsters. Gremlins director Joe Dante was quoted as saying at the time that he believed the PG rating was sufficient. "PG is not G. It specifically states parental guidance suggested."

By that time, Spielberg had amassed enough clout in the business that he could go to Valenti and make a case for a new rating that would better prepare parents for a film's content.

“It was sort of a perfect storm of movies that I either produced and directed," Spielberg explained in the MPAA video. "It all sort of came together and created this parental objection...and I agree with that, but I also felt it would’ve been unfair to have labeled either of those films [Temple and Gremlins] R. I called Jack Valenti and I said, ‘Let’s get a rating somewhere in between PG and R.’ Jack was proactive about it, completely agreed, and before I knew it there was a PG-13 rating.”

The ratings change suggestion, which would mark the first time the system was altered since its implementation in November 1968, did not go over well with everyone in the business.

"I wish they would leave the rating system alone," Gary Solomon, of Gulf State Theaters, was quoted as saying in a June 1984 article in THR. "People understand the ratings system the way it is and respect it."

The main complaint from most exhibitors was they were unsure how they would enforce the rating. They could check IDs for R, but it's not as if most 13-year-olds had IDs with their date of birth listed. They felt an unfair burden was being placed on them with the new rating.

Even Valenti, at first, wasn't sure if the new rating was the best idea.

"It's a fragile thing," he stated of the system in June 1984 to THR. "But an overwhelming number of exhibitors, producers and well placed observers seem to think a change is needed, and I am willing to go along with it."

By the end of that month, a new addition to the rating system was approved by the MPAA. The first film to receive a PG-13 from the organization was Garry Marshall's The Flamingo Kid, but because it was not released until December, the first film to come out with the new rating was Red Dawn, released in August.

The late Robert Selig, then president of the California Association of Theater Owners, was vocal in welcoming the change.

"I think it is an improvement because at least it puts more of a burden of responsibility on the parents from whom the code rating system was originally intended and still is," Selig told CNN.

The ratings system wouldn't change again until 1990 when the X rating, by then synonymous with pornography, was relabeled NC-17. That is also the same year brief explanations of a rating were added to better inform would-be viewers of a film's content.

Watch the scene that started it all, the MPAA video and a vintage CNN report below.

The Film Rating System from FilmRatings.com on Vimeo.