NEW YORK (Hollywood Reporter) – Leonardo DiCaprio and Brad Pitt almost certainly are strong contenders in the best actor category -- shining, word has it, in their respective upcoming movies, "The Curious Case of Benjamin Button" and "Revolutionary Road."

But they and others might be up against a subtle force they can do little about in the best actor race: Oscar voters tend to favor actors playing real people.

In the past six best actor races, there were three years in which an actor playing a real person was nominated alongside actors portraying fictional characters, and each time the actor playing a true-life person won. You have to go all the way back to the awards for 2001 to find a counter-example: Denzel Washington's victory for playing Alonzo Harris in "Training Day," which bested Will Smith as Muhammad Ali and Russell Crowe as John Nash. Otherwise, it was actors playing real-life figures -- Ray Charles, Idi Amin, Truman Capote -- who took the statue.

This year that means if even one from among the stellar group that includes Frank Langella (as Richard Nixon), Sean Penn (as Harvey Milk) and Josh Brolin (as George W. Bush) lands a best actor nomination, everyone else will have to weigh that added factor.

Best actress favors real personnages even more; the statuette has gone to women playing real people six of the eight years this decade. But with frontrunners such as Meryl Steep, Nicole Kidman and Sally Hawkins taking on fictional roles this go-round, this year may break form.

It's hard to pinpoint what makes Oscar voters tilt this way. But one likely factor is a frame of reference: Philip Seymour Hoffman acting and sounding like Capote probably will move the voter more than Terrence Howard's acting and sounding like Djay from "Hustle & Flow," a person the Academy member has never seen outside the movie (and hasn't seen at all if they've never seen the movie).

Plus, there's the impersonation factor: How could a voter not think Jamie Foxx is good; he even looks like Charles.

It wasn't always this way. In the 1990s, fictional characters bested real people in the best actor category seven out of nine times they went up against one another. And an actress playing a real person won only twice in the 1990s.

So what's changed?

For one thing, the rise of celebrity culture. The TMZs of the world have made it harder to separate actors from their roles since we now know them as real people -- unless they're playing other real people, in which case voters can identify with the person they're playing.

Even if DiCaprio and Pitt are unable to buck the recent trend favoring real-life portrayals, they can take solace in the likelihood they'll have other shots at the top prize. But the seeming voter bias toward real-life bios could also impact a few once-in-a-lifetime performances. Those include the comeback for Mickey Rourke, whose Randy the Ram in "The Wrestler" is a tragic figure to rival Willy Loman; Richard Jenkins, whose understated Walter Vale in "The Visitor" is exquisitely subtle; and Christian Bale, whose Batman in "The Dark Knight" is so darkly evocative.

Source: REUTERS