I think it's a little bit of a generational thing.

I was aging out of SA before 4chan even really got going (not maturing out, since I'm not that mature; just being done with college, moving on to professional school; not spending as much time on forums/etc). I never spent any real time looking at 4chan.

I of course know what image memes are, but if you just said meme to me with no context then I still think of it as the Dawkins 'Selfish Gene' idea.