Psych refuses to let the possibility of supernatural activity exist on its program; they always have to debunk it. It's what a lot of people like, but what I dislike about this show. Think about it, is the idea of someone being able to remember every piece of scenery he has ever seen in his life any more farfetched than a girl being possessed?
This was a good episode though, albeit aside from the anticlimatic ending. I don't even watch too many movies, but The Exorcist allusions were well-done and well-placed.
Definitely the best episode of the season so far. Let's hope it is only uphill from here.