In theater, the direction toward the audience is called “the fourth wall”. Most of the time, the characters on stage are not aware that we are there, watching them. Only in experimental theater and works inspired by Vaudeville do they actually look out across the footlights and acknowledge our presence.
In cinema it is rare indeed for a character to breach the fourth wall. The only person I can think of in cinema history who was able to do it well was Groucho Marx. Bugs Bunny had an easy time of it as well, but he had the superpower of being a toon.
Every time a fictional character acknowledges us, the “magic circle” of storytelling is weakened. Without this magic circle firmly in place, the entire trust relationship underlying our willing suspension of disbelief is prone to collapse.
One trick that is sometimes used in cinema is to erect an inner fourth wall. This was done rather famously in The Ring. When a nightmarish figure crawls out of a TV screen within the movie we are watching, we vicariously share the horror of a character in the story. as he experiences the unexpected collapse of the safe distance between “media” and “reality”.
As we move to more immersive media, such as virtual reality, I wonder how that will change our relationship with the fourth wall. Imagine, for example, some future where VR experience, within which we are watching a movie of The Ring. Within the movie, we see a nightmarish figure crawl out of a TV set, and we witness the mounting horror of the unfortunate character who was watching that TV set.
But then we see that same nightmarish figure crawling out of the screen that we are watching, and start to head our way. I wonder what we will think.