As an aside on the general conversation at hand, I suspect that the experience of humans is so much based on being a human that we struggle even to think about not being human; that we have so many assumptions we carry about what thinking is and what language is and so on. My favoured example of this is an experiment showing that humans have a special ability for recognising faces, based on giving other primates tests of face recognition. Go humans!
When the test was repeated, some time later, using faces from their own species instead of human faces, it turned out that they were actually also pretty good at it. The original experiment had used human faces to test with, because those were obviously much more distinctive. I suspect, but cannot prove, that we're trying to reason about non-humans from within a prison of human thought and experience and assumption that affects everything.
I suppose "introspection" is a pretty woolly term, though, and we could disagree about what the bounds of it are. The abstract about "metacognition" in rats is interesting but I think a little broader than what I had in mind.