So, I get what you're saying, but I don't think "signal" is a great term for that, because it comes from information theory, and there its definition more closely matches what you're calling "content".
I'm not sure what you could call emotional impact to make a similarly pithy description though.
Yeah, that's a good point - I have heard "signal" used more in this context in social sciences, like "dog whistle" in politics. But it'd be nice to come up with something clearer and just as pithy.
I'm not sure what you could call emotional impact to make a similarly pithy description though.