At the same time, we're told that all the sex and violence on TV doesn't matter, because it doesn't change peoples' behavior.

So, which is it? Does what we watch on TV change our behavior, in concrete ways, or doesn't it? I suspect that it does change our behavior, that the advertisers are right. (They're betting a lot of money on their position; I'd expect them to have some basis for doing so before committing that kind of coin.) But if so, then the rest of what we watch also changes our behavior.

And, obviously, so does our social media feed...