For those of you who came in late, "TMNT" is an acronym for Teenage Mutant Ninja Turtles, the comic book/ cartoon/ action figure/ movie phenomenon spawned in that most awesomely plastic of decades, the 1980s. When the Turtles last blasted across the silver screen, they were foam and latex puppets and costumes worn by little people.

In the new film, they are, naturally, CGI creations. Not that anyone ever thought Michelangelo, Donatello, etc., were actual flesh-and-shell beings, but the updated Turtles raise the question of what's more believable: an actual, if artificial, construct or a computer-generated image?

When Merian C. Cooper's "King Kong" debuted in 1933, Willis O'Brien's startling effects of the stop-motion ape climbing the Empire State Building stunned audiences. They had simply never seen something so fantastic interacting with the everyday. To look at the film today, the stop-motion animal is more quaint than terrifying, with its jerky movement and the visible handprints of the manipulating animators on its fur. But for die-hard fans, the original remains the quintessential "Kong," despite -- or, depending on your sensibilities, because of -- its technical limitations.

Director John Guillermin's 1976 remake made headlines by attempting to use a full-size Kong robot. In the end, the 40-foot, $1.7 million behemoth was stiffer than the 1933 puppet, getting a full minute of screen time. So the filmmakers ended up going with makeup/effects creator Rick Baker in a monkey suit, which looked like, well, an actor in a monkey suit (especially since he didn't bother to stoop like an ape when he walked).

Then came Peter Jackson's fully CGI "King Kong" (2005). Ostensibly an ode to the original 1933 film, Jackson's epic was chock-full of giant and/or icky movie monsters and a scarred, flea-ridden, fully-realized Kong (played in motion-capture by Andy Serkis). And while the film was visually dazzling, many critics felt that it was too much, particularly the scenes on Skull Island, populated with dozens -- nay, hundreds -- of digital creatures. Jackson seemed to fall victim to Lucas-itis: An overwhelming inflammation of too many digital effects, culminating in a lack of focus and often leading to eyestrain or headaches and an overall lack of emotional connection. In the end, Jackson's "Kong" did OK, but it wasn't as enthralling (or emotional) as its inspiration.

The second entrant in the "Star Wars" series, "The Empire Strikes Back" (1980), introduced the character of Jedi Master Yoda, brought to life by "Muppets" alumnus Frank Oz in the form of a highly intricate puppet. Despite sounding like a cross between Grover from "Sesame Street" and Master Po from "Kung Fu," Yoda became an instantly beloved part of the "Star Wars" universe. It was obvious that Yoda was a puppet, but it didn't matter. Yoda was real because, well, Yoda was real. When he reaches out and pinches Luke Skywalker's arm to explain how the force isn't bound by simple flesh, the interaction actually happens, to the benefit of both actor and audience.

Yoda remained foam and latex through the first "Star Wars" prequel, 1999's "The Phantom Menace," but by 2002's "Attack of the Clones," Frank Oz's participation was cut to mere voice-work. Yoda was now a full CGI creation, better able to leap into the air and do (very silly looking) light-saber battle with Count Dooku, but he was somehow ... less believable. The limitations placed on a puppet seemed to better fit a 900-year-old green dwarf than the airy weightlessness of CGI. It's sad to speculate that at some point George "the Terrible Tinkerer" Lucas may go back and replace the puppet Yoda in all of the films with a CGI creation.

Experimentation with CG people began in films like "Indiana Jones and the Last Crusade" (1989), "Terminator 2" (1991) and "Fight Club" (1999), but it wasn't until Ang Lee's "Hulk" (2003) that the humanoid star of a movie was computer generated (no, "Casper" doesn't count). While the general public had accepted the body-built but still human Lou Ferrigno as Bill Bixby's angry alter-ego in "The Incredible Hulk" TV show of the 1970s, the comic-book basis was in fact a far more imposing creature: a tank-sized beast that couldn't even find pants at the Big & Tall shop (especially not in purple). But, despite his gargantuan size, the bigger, badder movie Hulk failed to connect with an audience. A convoluted, overly serious script was primarily to blame, but could the fact that the Hulk wasn't "real" have something to do with it?

All of this is not to say that some movie characters shouldn't be rendered digitally. Take Ben Grimm, a.k.a. the Thing from "Fantastic Four." In the Marvel Comics universe, the Thing and the Hulk are about the same size and have gone green-toe-to-orange-toe many times. In the movies, Michael Chiklis buried under makeup just isn't as imposing (nor as tragic) as the character needs to be. Especially considering the character's lack of human flesh and hair (two of the hardest things to realistically animate), the Thing's rocky form seems to beg for the CG treatment (after all, both the flamed-on Human Torch and the Silver Surfer are fully CG in the upcoming sequel "Rise of the Silver Surfer").

The key to accepting CG characters seems to be integration (ain't it always?). Last year's "Superman Returns" is in a way a curious example of movie effects coming full circle. In the "Superman" movie serials of the 1940s, when the Man of Steel (played by Kirk Alyn) would take flight, the live-action Superman would suddenly be replaced with a crudely animated character. That obvious cartoon has very little in common with the sophisticated CGI Superman used in many flying shots in "Returns." Still, while audiences knew that computer graphics were being used, it was the combination of those shots with the actual physical effects of Brandon Routh on cables and gimbals that made it work. If you don't know which shots are "fake" and which are "real," it becomes easier to get lost in the finished product.

But we still have to opine that the most dazzling flying shot in "Superman Returns" didn't match the thrill of seeing that first majestic flight of Christopher Reeve in 1978's "Superman." That movie drew audiences to the theater with the promise of making you believe, for the first time, that a man could fly, and it did, with nary a computer involved.

While the claim is that today's audiences are more "sophisticated" in expecting far more from their special effects, we'd say it's actually something less meritorious. Today's audiences are more cynical. We not only expect that modern effects are flawless, we demand it, and anything less than 100 percent believable is decried as having crappy effects, regardless of how much imagination and toil was involved.

Maybe modern CG updates of old characters don't resonate as strongly because the wonder's gone. The sad fact is, movie magic has become a thing of the past, replaced with cold movie science. Due to that catchall answer of "computers," nobody ever gasps at the fantastic and asks those five words that entranced moviegoers for practically a century: "How did they do that?"

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