LOS ANGELES  - If an average woman can spend hours ruminating over an outfit, imagine what a star goes through choosing a look for a red carpet like the one at the Golden Globes.

Their gown choices are about as spontaneous as deciding who's going to star in $100 million movies. Both convey image and perception, both can triumph or fail. The cost is high in both cases.

This year's big-ticket Globes nominees — Natalie Portman, Michelle Williams, Nicole Kidman, Angelina Jolie and Halle Berry — are expected to turn out an impossible combination of Grace Kelly-meets-Audrey Hepburn-meets-Sophia Loren looks.

That in itself is an image-juggling act: Stars use red carpets to shape-shift their public image, their status, their career trajectories and even their love lives.

It's hard to believe, but before the late 1990s, stars came casually to the Globes.

"They'd wear pantsuits and little glasses to read their speeches," says Carlos Souza, global ambassador for the Valentino brand. "Mr. Valentino would watch, get so angry and say, 'Where's the glamour of Old Hollywood?'"

The tables turned in 2000, when Berry, nominated for Introducing Dorothy Dandridge, turned up in a sophisticated white Valentino stunner — to the collective reaction of "Wow!"

"That dress was the game-changer," says Phillip Bloch, the stylist who dressed Berry in her early iconic looks. "It upped the ante for Globes style and was a career-making dress: the perfect storm of right woman, right dress, right moment. We were going for Natalie Wood, not Raquel Welch. Beautiful, not va-va-voom. Halle was already sexy; we wanted her to look like a real actress. That began the time when a dress could actually make a career."

Now it's reached maximum combustion.

"Fashion and image has become a big part of my job," says one Globe nominee's high-powered manager. "You don't want to alienate your audience by going over the top, but you can't overlook that a young female audience is affected by what actresses wear."

With all that weight resting on a choice, lots of cooks weigh in: stylists, plus managers, PR and relatives, to name a few.

"I had a boyfriend want to change the color of a couture dress the night before because he liked blue better than pink!" Souza laughs.

Notes stylist Elizabeth Stewart, who's working with Winter's Bone nominee Jennifer Lawrence: "It changes from star to star. Some know exactly what they want, some need a committee."

Case in point: Julia Roberts favors stark, simple dresses, even when attending the Globes in 2001, where she won for Erin Brockovich. But niece Emma Roberts was present when she debated the regal, black-and-white vintage Valentino she wore to the Oscars weeks later.

"Wear that one, Aunt Julia!" she said. "That's really glamorous, and make sure to show the back!"