Fending off stiff competition from cable television, Hollywood has been searching for ways to give movies an excitement worth leaving home to view. That has sparked the entrepreneurial fire of at least two young production companies.

Showscan Film Corp., founded last year by Robert Brock and Douglas Trumbull, unveiled a new cinematographic technique in February that promises the thrill of three-dimensions without the bothersome glasses. Showscan's secret: The speed of the film is more than doubled, providing 60 frames per second, instead of the standard 24. Trumbull discovered that speeding up the film creates surprising reactions in viewers.

"We showed identical films photographed and projected at rates from 24 to 72 frames per second to about 60 people individually," says Trumbull, "and simultaneously ran a series of tests on them, such as electrocardiographs and skin-response measurements. The results were extremely high for rates over 24 frames per second." It seems viewers experience high-speed film images in much the same way that they experience reality, he explains, because they are receiving visual cues at practically the same speed that they would in real life.

To showcase the technique, Brock plans to attach theaters to most of his 201 Showbiz Pizza Place restaurant outlets. Four prototype theaters are now showing the first Showscan film, a thriller called New Magic. In Dallas, one of the sites of the preview, Brock says business at the related restaurant rose 50% during the weeks the film has been playing. He pre dicted that as many as 100 more theaters and several new films will appear in the next year if other investors get involved.

The idea at three-year-old Sharp Features Inc. production and distribution company in Cambridge, Mass., is to get viewers involved in the films. Neil T. Evans and Jamil Simon are marketing "Reactivision/Choice-A-Rama a film technique that as Evans put it, allows audiences to "tell a movie where to go."

Reactivision premiered last October in Leominster, Mass., in Goodbye Cruel World, a fast-paced comedy for the college set. At various points in the less than compelling plot, a comic appears on screen to offer the audience four choices about which way the story line should go. The audience whoops and hollers to indicate its preferences, while a multicolored electronic totem pole at the screen's side registers the level of their appreciation The choice that registers highest on the pole is threaded into the projector, and the film continues.

Although the technology has received kudos from audiences and industry moguls alike, the movie itself was a bit of a flop. So Simon and Evans are now putting together financing for a new film that they hope will better demonstrate Reactivision's potential. But the genre will still be limited to comic adventures. "This is not something that would work with [the movie] Terms of Endearment," concedes Simon. "You couldn't exactly ask the audience, 'Does she die or does she not die?"