It says a lot about my age that I spent much of Paranormal Activity admiring the haunted couple's house and thinking that if I had their two-storey three bedroom in San Diego* I'd make peace with the entity and maybe plant more things in the garden. At the very least, Katie and Micah could change sides on the bed or sleep with the door shut so the nameless thing would have to walk around the bed to get to whichever one of them it's after.
That the pair do not is the fly-on-the-wall POV equivalent of a Halloween teenager going outside at night to see what's making the noise in the pines. Lack of common sense is the basis for good horror movies. Katie and Micah have none but are proficient in the ways of video editing and digital sound enhancement.
In the old days of The Entity or The Exorcist scientific detection of a ghost required calling in experts from a university: even the kids in the first Nightmare On Elm Street had to check into a monitored sleep clinic. Now all victims need to do is go down to Radio Shack, assuming the software didn't come bundled on their PC. The nagging problem with Cloverfield was that no modern amateur camera man would be using a device without shake correction, let alone cut away from a shot of the monster itself. Paranormal Activity's unblinking hi-def monitoring of the supernatural is not only credible but mandatory for modern audiences.
When Micah does capture the entity's sounds and Katie and her sister regard the technology he is using without comment, I became distracted by the level of technological sophistication I was witnessing. If both the characters and the audience understand how digital sampling can catch a ghost, will spooks become rationalised to the point when they are never scary again? This in a way is the movie's theme: tech is the protagonist and evil -- as represented by Micah flicking through the pages of a book of woodblocks and engravings of devils -- is the antagonist.
A truly creepy moment in Paranormal Activity is Katie's never-discussed hobby of threading beads to make dream catchers: a buried hint that she may be in communication with the spirit world, or that her family has some connection to playing with such entities and thus "opening the door" to them. Katie's sister has also witnessed to the scary phenomenom, and when the two women sit to have "girl time" they weave dream catchers together - another red light.
These scenes reminded me of The Blair Witch Project at its best, such as early in that film when the documentary makers interview a local eccentric who reports seeing a women with strangely hairy arms, or local accounts of a woman who crosses a running stream with her feet slightly above the ground. The images were clues to witch folklore and resonated in our Jungian unconscious at a deep level. That the audience had to create them in their own imagination, making up for the fictional and real filmmakers' lack of budget only added to their effectiveness.
Paranormal Activity has a more professional structure than Blair Witch, which makes it less scary overall: because there's none of the wandering we trust the filmmakers to scare us at certain points, which they do. The attractive young couple's lack of friends and neighbours requires suspension of disbelief and as the story progresses and the manifestations become more literal they become less frightening but the movie is still a ripper, particularly when the couple's disharmony literally invites bad things to happen. Simple is scary, but making things scary is not simple. The best technology is always well-buried.
*Nobody knows what it really means.