THREE WEEKS have elapsed since "Paranormal Activity" crept into local theaters on little Internet feet.

It's now the No. 1 movie in America, so it is no longer ethically possible for me to ignore it. In my defense, the first week's showings were at midnight, way past my bedtime.

Also, the studio did not have a freebie screening for us critics, so I had to pay $10 to see "Paranormal Activity," and about a million commercials for crappy shows on the CW. Why do you people put up with this? There should be tea parties, or something, and the practice should be stopped.

Anyway, three weeks gave me plenty of time to absorb and consider the hype. On one hand, the movie has been compared with that other low-budget, 'Net-based horror phenomenon, "The Blair Witch Project."

On the other hand, it's said to be a throwback horror movie that has used old-school suspense techniques to beat down "Saw VI," whose stupefying gore has begun to bore even hard-core fans.

There's truth to both. "Paranormal Activity" borrows the found-footage gimmick of "TBWP," and the limited perspective - we see only what the camera sees. What does the camera see? A woman (Katie Featherston), with an ample bosom - a sign that "Paranormal Activity" director Oren Peli understands the most indispensable ingredient of the horror genre.

Featherston plays Katie, one half of a young San Diego couple stalked, in their tract home, by an invisible demon. Boyfriend Micah (Micah Sloat) buys a camera to document the haunting, resulting in deliberate camera-eye myopia, but Peli finds a simple and effective way to expand the visual perspective.

Micah uses the camera for nighttime surveillance, so we see wide-angle shots of the couple in bed as the invisible demon leaves chalky footprints, plays with the sheets, slams the door, and eventually takes more aggressive action.

These are some of the slowly doled out thrills that give "Paranormal Activity" its old-school feel. The movie has some panting admirers invoking Val Lewton, but "Paranormal Activity" is more concerned with pop mythology than the psychology of its paper-thin characters. (As in "TBWP," there is improvised dialogue that too often takes the form of hysterical bickering.)

Still, there's more going on here than simple scares. There are two invisible demons in the story - one is Micah's arrogance, his Richard Heene-like interest in what the camera can capture, and what those images might leverage. (Micah, we're told, is a day trader.)

The couple is sternly advised NOT to communicate with or bait the demon, but Micah cannot resist. He taunts and goads the demon - first as a skeptic and then as a greedy videographer, and you don't have to be Val Lewton to know how that turns out.