By most accounts in Hollywood, he is one of the best actors of his generation, but for Ryan Gosling there will be no major studio movies, no comic book hero roles like Spider-Man or goofy romantic comedies.

At age 30, Gosling still prefers movies like his new "Blue Valentine," which debuts in theaters on Wednesday. It was made outside Hollywood's major studios and is an adult drama -- currently the most unappreciated film genre at box offices as audiences seek escapism and laughter in movie theaters around the holiday season.

But dramas generally offer the most challenging roles for actors and as much as anything else, Gosling loves a challenging acting job -- even if he's not quite sure why.

"Some people eat and eat and don't know how to stop," Gosling told Reuters. "For me, it's the same thing with film. I'm compelled to play these kinds of characters. Even when I'm in it, I have moments of lucidity where I'm like, 'Why am I doing this?' And I don't know why. Not knowing is what keeps me interested."

Gosling's only mainstream Hollywood movie hit was "The Notebook," a romantic drama based on the Nicholas Sparks novel that took in a surprising $81 million at U.S. and Canadian box offices. It told the tale of an older man telling audiences how he first fell in love with his wife many years before.

As a child actor, Gosling worked in TV before breaking out in "The Believer," a Sundance Film Festival darling in 2001 that earned him an Independent Spirit Award nomination for best actor playing a young Jewish man who is anti-Semitic.

By 2007, he had earned an Oscar nomination for his portrayal of a drug addicted school teacher in another independently made movie, "Half Nelson," which followed his Golden Globe-nominated performance as a young man who falls in love with a sex doll in "Lars and the Real Girl."

Gosling does not consciously avoid big studio movies. Rather he said he feels "there's more freedom and more experimentation" in independent films. And "Blue Valentine" is no exception, thanks to an unorthodox filming process that proved to be the most experimental of Gosling's career yet.

The end result has already rewarded the actor with another Golden Globe nomination, and led to Oscar buzz -- and a little controversy -- for he and his co-star, Michelle Williams.

CHALLENGING ROLES

Gosling portrays Dean, a man whose relationship with his wife Cindy (Williams) is crumbling. The film moves between Dean's and Cindy's romantic past and heartbreaking present, showing the stark contrast between the start of a beautiful love and a fractured relationship that's hanging by a thread.

The movie debuted to good reviews at 2010's Sundance and later drew controversy in the United States for its sex scenes, which were deemed too racy for any audiences other than adults. The protest has since cooled down.

For Gosling, the unconventional way in which "Valentine" was shot proved to be among its big challenges. Director Derek Cianfrance first filmed all the scenes of Dean's and Cindy's past, then gave the actors one month off work before shooting the present-day scenes of their disintegrating relationship.

"Michelle and I didn't really know each other when we first started shooting the movie," Gosling said. "In those first scenes where Dean and Cindy were getting to know each other, we were getting to know each other too."

Cianfrance also filmed the beginning scenes in long, consecutive takes without any re-shoots to capture the purity and realism of a couple falling in love.

That strategy contrasted starkly to shooting the present, where Gosling said the director had the actors sometimes perform 50 takes of a single scene "so that it just gets old, like you're not able to surprise the other person anymore."

The actor said Cianfrance also whispered in his ear things such as: "'Whatever you do, don't let her (Williams) leave the room, don't let her leave the embrace.' Then he'd go to Michelle and say, 'Leave. Get out. You're being smothered.'"

That sort of duplicity set up an interesting dynamic between Gosling and Williams, both of whom had been attached to the project since 2005 and 2003, respectively.

"Derek kind of set it up like a 'who won that round?' game," said Gosling. "If Michelle left the embrace, I was upset for my character because it meant that I'd lost. But there's a triumph on some level because your co-star achieves this emotional state that you've been talking about for years."