Universal Pictures originally provided this undated file photo of Katherine Heigl and Seth Rogen in Knocked

Movies are supposed to be about getting lost in emotion. But one scientist has broken down the film industry to cold, hard facts.

A psychology professor at the University of California, Davis, has done a statistical study of thousands of movies to determine what makes them critical darlings or box office hits.

Films that earn awards and praise from reviewers tend to be R-rated and based on a true story or a prize-winning play or novel, says professor Dean Simonton. The original author or the director usually have written the screenplay.

Big-budget blockbusters – comedies, musicals, sequels or remakes – don’t ordinarily draw acclaim, Simonton found. Neither do summer releases, PG-13 movies, movies that open on thousands of screens or ones that have enormous box office numbers in their first weekend.

“I had this hope that there was a difference between blockbusters and really great art films – films that can be considered great cinematic creations,” said Simonton, who presented his findings Friday at the annual meeting of the American Psychological Association in San Francisco. “It was gratifying to find out they’re very, very different and you can find out what’s different about them.”

Simonton says he’s not a movie buff – “I’m a consumer like everyone else” – but in his studies of genius, creativity and leadership, he started compiling data about the collaborative process of filmmaking in 1999.

“Brokeback Mountain” is a prime example of what Simonton discovered. It was rated R, had an 87 percent approval rating on the Metacritic.com Web site and it came out at the height of prestige-picture time in December 2005. It featured a top-notch creative team, including director Ang Lee and screenwriters Larry McMurtry and Diana Ossana, working from a short story by Pulitzer Prize winner Annie Proulx. The film cost $14 million to make and grossed nearly $175 million worldwide. It was nominated for eight Oscars and won three.

But then there are exceptions, like this summer’s “Knocked Up.” It’s also very much an R-rated movie, but it’s a comedy that’s gotten 85 percent positive reviews on Metacritic and it came out in June. Judd Apatow, who has long enjoyed a cult following, wrote and directed it. The film cost an estimated $33 million to make and so far has grossed $164 million worldwide. It’s probably not going to win any Oscars, but who knows?

Stephen Whitty, chairman of the New York Film Critics Circle, says Simonton’s findings weren’t terribly surprising.

“Anybody watching the Oscars even casually knows that they tend to reward certain things they love – they love biopics, they love when a pretty woman puts on some ugly makeup to play a character in trouble,” said Whitty, critic for The Star-Ledger of Newark, N.J. “They’re not going to spend three or four hours of prime time rewarding movies that flopped badly at the box office.”