Setting
It's Not Always Sunny in Philadelphia
The Sixth Sense's Philadelphia is extremely picturesque, but spooky, too. The bulk of the movie takes place in the fall, with lots of yellowing and falling leaves and chilly (we assume) winds. There's actually a lot of emphasis on cold in general, of course, since Cole's gaggle of ghostly followers seem to make the thermostat plunge wherever they are. Maybe the dead are just extremely energy-conscious.
So between the season and the dead, the atmosphere is literally and figuratively chilly, which makes it the perfect setting for our modern-day ghost story.
Atmosphere is totally crucial to ramping up the fear index in key scenes, though. Take Cole's trip to Kyra's funeral as an example. At first, we have no idea what he's up to. We just know that he and Malcolm are sneaking into what appears to be a wake.
You'd think that whole escapade would add enough suspense, but Shyamalan has to up the ante. They end up in Kyra's room, which is filled with puppets. If you've ever seen Child's Play—or, you know, any real-life marionette—you know that they can be seriously creeptastic. They look like little people. But not. It's the "uncanny valley" experience.
Anyway, those things are all over Kyra's room while we're waiting on pins and needles to find out why Cole and Malcolm are there. There was probably enough suspense going already just in terms of the actual plot, but Shyamalan makes Kyra's room extra creepy just to make sure we can barely stand to watch. It's an impressive and horrifying use of mise-en-scène.
So, in short, the setting does a good job amping up the mood and overall suspense. There's more emphasis on the character dialogues than on the backdrop or scenery where these chats are taking place, of course, but the setting definitely plays a big role in upping the spooky factor.