Inception facts

In this brief article from The HuffingtonPost, a psychologist, Matthew Edlund, explains what is true and what is false in the dream world of Inception. He says that an outside person cannot insinuate themselves into another person's dream, but that's not correct. Maybe not in the way showed in the movie, but if you hear music or running water or a barking dog, etc, etc, while you're dreaming, you will incorporate that into the dream.

ADDENDUM

I went back and looked at the original article again, and the author says that you can insert content into a dream, so I guess that's the distinction that he's making - content like music, but not your whole self.