THE DUH FILE

If you’ve watched television lately and have seen an ad for Tom Hanks’ directorial debut, “That Thing You Do!,” you’ve probably heard the seemingly unnecessary tag line: “Only in theaters.”

The line is the brainchild of Bob Harper, president of marketing at 20th Century Fox, who started using it to promote the summer blockbuster “Independence Day.” Harper says the line merely helps to underscore that a first-run movie can be seen nowhere else, even in the midst of the ever-expanding smorgasbord of televised fare.

“We were just looking for a way that our theatrical material could be distinguished from what you see on TV,” he says. “There’s so much entertainment on television.”

Because these commercials air on television, studio executives wanted to make sure that viewers knew this movie was not something that could be seen on TV.

“It’s sort of an efficient way to get two messages across,” Harper says. “It’s just to let people know ‘Hey, it’s only in theaters that you can see this.’ We’re always looking for ways to motivate you to go out and see it. It’s telling people, ‘If you liked what you just saw, then it’s in the theaters.’ ”

But isn’t that a little, er, obvious?

“We [who are in or close to the film industry] look at it as ‘Of course, it’s only in theaters. It’s a new movie,’ ” Harper explains. “But everybody in the middle of the country doesn’t know that.”

Studios typically begin advertising a movie about three weeks before it opens in theaters and continue for another four weeks or so. Though residents of Los Angeles are steeped in information about upcoming movies, in many parts of the country there can be little or no advance word of mouth on a picture.

“Audiences may be looking at the commercial for the first time,” Harper says. “It’s simple to inform them of this thing. It’s a quick, easy line, and you don’t lose anything.”