It's rather interesting. In Communications, we learned about the Kuleshov Effect, in which the onscreen appearance and conveyed emotion of an actor can be manipulated by context.

Then this was posted on Lotrboys_daily.

Dude, what are silly captions if not the ultimate proof of the Kuleshov effect? We know that the actors are obviously expressing sentiments very different from the suggested dialogue in the caption, but in most cases, especially with really funny captions, it really looks as though the actors could be saying the captioned words. In class, a bunch of the students were still skeptical about the effectiveness of Kuleshov (myself included), but now I'm convinced. I'm so going to mention this to Professor Messaris on Tuesday.

Ah, Visual Communications. It has changed the way I see the world. Or at least movies.

</dork>