If you're a glass-half-empty kind of person, the downside of the technological revolution that put lightweight, inexpensive video cameras in the hands of regular folks would have to include America's Funniest Home Videos, the celebrity sex tape (see Kardashian, Kim; career launch-pad of) and the Paranormal Activity franchise.

These movies require audiences to stare at minute after minute of tripod-mounted vidcam footage of ordinary rooms in the hopes that a light fixture might start swinging back and forth -- on its own!

But with the hefty international box office haul from the micro-budgeted Paranormal Activity movies, it would appear we're going to be seeing a lot more of these found-footage fright-fests. (With so much of the films' appeal based on audiences scanning an image looking for one subtle shift, the Paranormal Activity series is the Where's Waldo? of horror movies.)

For those of you not keeping up, the first PA followed a young couple in a non-descript San Diego house who heard strange noises and observed inexplicable phenomena involving car keys and other mysteriously-relocated household items. Katie (Katie Featherstone) claimed that she'd been haunted by a threatening invisible presence since childhood, so her boyfriend set up a camera in their bedroom to try to catch the boogeyman in his tracks.

Moral? Don't futz around with forces you can't understand.

A year later, we got the second movie, which was simultaneously a prequel and a sequel, as we discover that the house-haunter might have been sent Katie's way by her sister Kristi (Sprague Grayden) in an attempt to protect Kristi's infant son. Moral? The first Paranormal Activity grossed nearly $200 million worldwide.

So now we get PA3, which takes us back to Katie and Kristi's childhood in 1988 in an entirely different nondescript house. (And seriously, kudos to the art direction team - audiences take lived-in-yet-personality-free sets like this for granted, but they're as challenging to assemble as, say, a cozy New York loft.)

The girls live with their mom Julie (Lauren Bittner) and her boyfriend Dennis (Christopher Nicholas Smith); Dennis shoots wedding videos for a living, so when bumpy noises and odd occurrences start popping up, he sets up his cameras all over the house to try to figure out what's going on.

Of course, this is 1988 we're talking about, so PA3 has fun with the analog nature of VHS cassettes and giant timecodes in clunky fonts. From a suspense standpoint, one of the film's smartest moves is to have Dennis mount a camera on the base of an old oscillating fan, so the camera can slowly pan back and forth between the kitchen and the living room.

The agonizing wait for the camera to move from side to side generates some of the film's best jolts, but late in the game.

Directors Henry Joost and Ariel Schulman (perpetrators of that phoney-baloney documentary Catfish), working from a script by Christopher Landon, backload all the best scares to the film's last half hour or so, and while horror films should certainly strive to build tension, it only works if you've managed not to bore the audience silly during the first half.

Also not helping matters is the fact that PA3 decides to attempt to answer the questions about where the invisible presence came from and why he's chosen this particular family to annoy. Monsters tend to be most frightening when they are mysterious and inexplicable; start loading on backstory, and the whole enterprise becomes a lot less scary. The thing that goes bump in the night can't scare you as much if you know what the thing had for breakfast and who is its favorite Spice Girl.

Not that any of this will matter much to the many fans of the PA movies out there - the same production team is in place, and PA3 goes after the same kinds of holy-crap-the-sheet-moved shocks as the first two, so it will no doubt be just as successful. (Once again, the man gets something crazy on camera late in the story, and the woman conveniently refuses to watch because she's had enough of his shenanigans.)

If the prospect of staring at surveillance footage in the hopes of a sudden surprise didn't give you goosebumps in the first two movies, Paranormal Activity 3 isn't going to bring you into the fold.

But it's also possible that, two movies later, even die-hard supporters are going to find all this stuff dully familiar.

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