Pretty much everyone who plans to see Paranormal Activity 3 this year knows exactly what to expect: intentionally “amateurish” footage, minimalistic scares that suggest the presence of supernatural forces, and a final scene that packs a big punch. So, if the PA formula is so predictable, why watch it being executed a third time?

The answer? Because, based on the Paranormal Activity 3 teaser and a trio of freshly-released viral clips, this new installment in the franchise looks to be one of the most legitimately spooky films of the year.

If this past spring’s sleeper hit, Insidious, was the cinematic version of a high-end haunted house attraction, then Paranormal Activity 3 looks to be the film equivalent of walking through the woods at night: Every mysterious noise and spooky shape you pick up on leaves you feeling anxious, even though you realize there’s virtually no chance that something terrible is going to happen to you. Well, until you stop paying attention and walk face-first into a tree, at least. 😉

Point being: These viral clips from the third Paranormal Activity flick don’t tread on any untested territory – they feature static-filled VHS footage, full of mysterious events and brief snippets of characters screaming in terror – but they’re nonetheless quite effective, all things considered.

See what we mean by watching all of the Paranormal Activity 3 clips below:

For those late to the party: Paranormal Activity 3, as far as we know, takes place primarily in 1988, back when sisters Katie and Kristi (whose adult versions were played by Katie Featherston and Sprague Grayden in the previous PA films) were both just young girls. The threequel is therefore actually a prequel that promises to shed light on the siblings’ early encounter with a demonic entity – a traumatizing incident that, for reasons soon to be revealed, the grown-up versions of Katie and Kristi cannot actually remember in detail.

Paranormal Activity 2 scriber Christopher B. Landon penned the screenplay for PA 3, which features Catfish filmmakers Henry Joost and Ariel Schulman in the directors’ chairs. Seeing how all three of these gentlemen are now well-versed in the art of the (fake) documentary format – and have previously exploited it for maximum effect – there’s good reason to think they’ll deliver a horror film that’ll keep fans of the PA series happy… and, probably, one that also rakes in more than enough cash to ensure that Paranormal Activity 4 happens (for better or for worse).

Paranormal Activity 3 arrives in U.S. theaters on October 21st, 2011.

Source: Paramount Pictures (via BD Horror News, Dread Central, and STYD)