Ever since George Arliss received the 1929 Academy Award for the lead in biopic “Disraeli,” Oscar has had a fondness for actors playing real-life people.In the 2004 derby, four of the five actor nominees portrayed nonfictional personalities, including winner Jamie Foxx for his turn as Ray Charles. Perhaps not coincidentally, the year before that, Charlize Theron took home the actress prize for playing serial killer Aileen Wuornos in “Monster.” The previous year, Nicole Kidman transformed herself — nose and all — into Virginia Woolf (“The Hours”), and was honored with the actress laurel. In 2002, Adrien Brody was a late-stretch runner who eventually won for “The Pianist,” in which he played Warsaw ghetto survivor and musician Wladyslaw Szpilman. In 2000, Julia Roberts was the real-life “Erin Brockovich” and in 1999 Hilary Swank’s portrayal of murder victim Brandon Teena won her an Oscar for “Boys Don’t Cry.” This year, the list of potential actor nominees includes David Strathairn’s Edward R. Murrow (“Good Night, and Good Luck”), Philip Seymour Hoffman’s Truman Capote (“Capote”), Russell Crowe’s Jim Braddock (“Cinderella Man”), Jake Gyllenhaal’s Anthony Swofford (“Jarhead”), Colin Farrell’s Captain John Smith (“The New World”), Joaquin Phoenix’s Johnny Cash and Reese Witherspoon’s June Carter (“Walk the Line”), among others. Theron, another possible contender for “North Country,” plays a character based on a real-life woman pursuing a sexual harassment lawsuit. So does playing a role taken out of the newspapers or history books ensure a leg up come Oscar time? In 2003, no lead actor nominated was playing a real person. In 2000, Crowe, who twice in his career has been nominated for bio perfs (“The Insider” and “A Beautiful Mind”) won for the fictional “Gladiator.” Back in 1992, Denzel Washington’s Malcolm X lost to Al Pacino’s “Hoo-hah!” colonel in “Scent of a Woman,” and Washington lost in 1999 to Kevin Spacey (“American Beauty”) the year he was nominated for playing a real-life boxer in “The Hurricane.” It’s an issue that’s thorny and slippery, and points up the occasional chasm between Oscar voters and the world at large. “Do real people really care about actors playing other real people?” asks Joe Morgenstern, the Pulitzer Prize-winning film critic for the Wall Street Journal. “Not when the realities are unknown to them. I doubt that most moviegoers are turned on by the prospect of watching bigscreen evocations of Edward R. Murrow or Truman Capote, fine as the performances may be. “But other actors, and critics, get a kick out of such mimicry, thus enhancing the actors’ chances at Oscar time. Still, mimicry alone doesn’t do it. If it did, an Oscar could go to a parrot. The remarkable accomplishment of Philip Seymour Hoffman, or of Jamie Foxx last year, was to internalize what seemed to be the whole person as well as externalize the twitches and tics.” But Hoffman’s Capote and Foxx’s Charles are well-known figures with well-know mannerisms. Similarly, Cate Blanchett, who did a dead-on impersonation of Katharine Hepburn in “The Aviator,” walked way with the 2004 supporting award. More curious are the Oscars that went to Kidman and Roberts, both of whom played little-known real-life women. “Back in the old days,” says veteran Time magazine critic Richard Schickel, “Paul Muni was always getting nominated for playing people like Emile Zola. I guess the difference now is that actors are playing more contemporaneous people, not 19th-century French authors. The interesting issue is where does pure imitation leave off and creative acting begin.” Schickel raises two issues that have become constants in the world of Oscar-watching: Voters will predictably go for roles in which the performer is playing someone handicapped, and playing it to the hilt. In this context, Foxx’s award for “Ray,” he says, might not have been so much about Charles, but the fact the musician was blind. “The sure road to an Oscar,” he continues, “seems to be playing a real-life person with a mental or physical disability.” Which would seem to leave out this year’s crop of Oscar hopefuls, who might have to rely on the quality of their performances, rather than the accuracy of their imitations.