This undated photo, supplied by Universal Pictures, shows Vince Vaughn and Jennifer Aniston in their new film, 'The Break-Up.' The couple, who became the latest Hollywood hookup, got together while making 'The Break-Up,' which opens Friday, June 2, 2006.(AP Photo/Universal Pictures,Melissa Moseley)

LOS ANGELES - Elizabeth Taylor and Richard Burton. Nicole Kidman and Tom Cruise. Melanie Griffith and Antonio Banderas. Alec Baldwin and Kim Basinger. Penelope Cruz and Matthew McConaughey. Jen and Ben. Angelina and Brad.

High-profile pairings all. And all share another thing: love bloomed on the set.

The latest addition to the list, Jennifer Aniston and Vince Vaughn — whose coupledom has been reported widely, though they refuse to officially confirm it — met while making "The Break-Up," which opens Friday.

Cynics might say these set-sparked couplings are nothing more than publicity stunts. Experts, though, insist workplace romances are common and make perfect sense. The workplace for movie stars just happens to be bathed in a spotlight.

Celeb partnering is "an almost surreal example of what happens in real life," said Kristin Kelly, spokeswoman for the dating Web site Match.com. "It's natural for people who are in the same profession who spend so much time together to forge a relationship."

There's more to it than that, said Helen Fisher, a biological anthropologist and author of "Why We Love."

Like attracts like, in terms of looks and lifestyle, and "a movie star rarely runs into somebody as good looking as they are," Fisher said. Except maybe on the set.

Actors might also be more vulnerable to falling in love. Those who seek performance as a profession tend to be risk-takers, she said.

Plus, she added, the on-set environment can induce an intoxicating physical reaction.

"Any kind of novelty or excitement drives up dopamine in the brain, and dopamine is associated with romantic love," Fisher said. "I wouldn't be surprised if movie sets literally set the stage for romantic love."

It's easy to believe, considering some stars fall for their leading ladies or men again and again. Cruz dated Cruise ("Vanilla Sky") and Matt Damon ("All the Pretty Horses") before hooking up with McConaughey, her "Sahara" co-star.

McConaughey was previously linked with two of his "A Time to Kill" co-stars, Ashley Judd and Sandra Bullock. Cruise connected with Kidman, his wife of 10 years, on "Days of Thunder."

Ben Affleck met Jennifer Lopez on the "Gigli" set and they got engaged. Then he met Jennifer Garner on "Daredevil" and they got engaged. He and Garner are now married and have a 6-month-old daughter, Violet.

Pitt hooked up with his former longtime love, Gwyneth Paltrow, while filming "Seven." He previously dated Juliette Lewis, his co-star on the TV movie "Too Young to Die," and Jill Schoelen, with whom he starred in 1989's "Cutting Class."

Actors keep a round-the-clock schedule during filming, working long hours away from home for weeks at a time. An exotic locale only adds to a feeling of unreality, said Jeremy Ritzlin, a West Hollywood psychologist.

"It's like a summer-camp romance," he said.

Then there's the chemistry component. The same on-screen compatibility that makes a movie successful can translate into offscreen romance, Kelly said.

"You can't fake that kind of chemistry," she said. "It's very easy for it to go from something that happens when the camera is rolling to something that happens when the camera's not rolling."

In "The Break-Up," Aniston and Vaughn play a couple ending their two-year relationship while still living together. They spend much of their screen time fighting. The shooting in Chicago took a month and a half — more than enough time, it seems, for romance to bloom?

Aniston was fresh off her very public split from Pitt in March 2005 when "The Break-Up" offered an outlet for her hurt feelings, plus a charming leading man.

Publicity-wise, the twosome's offscreen dallying has helped the film, said Adam Fogelson, president of marketing for Universal Pictures.

"Just about everyone knows this movie is coming," he told "Entertainment Weekly." "All the attention that Vince and Jen have gotten over the last many months is substantially responsible."

Besides building buzz, celebrity relationships can build careers, said Hollywood publicist Michael Levine. Kidman rose to the A-list after hooking up with Cruise, who had a similar career-boosting effect on Cruz.

Fans like star couplings too, Levine said.

"It plays to the need of the audience for a fairy-tale story line," he said.

But it's not just the on-set environment that makes for star-star romance, Kelly said.

Though single celebs presumably have their pick when it comes to potential partners, they have to be wary of who they choose, she said. Sometimes only another star can understand them.

"(Celebrities) are very guarded and don't have a lot of interaction outside their small social circle," she said. "When they meet someone living in their same surreal world who understands it, there's a connection."