I get the impression this isn't really what is meant by introspection here. I think it means much more plainly that the model is aware of its own "state of mind" so to speak, not so much the sense of reflecting on one's actions. I don't think you'd necessarily need training data about humans reflecting on their behavior for the former to come about in a model, i think it'd have more to do with the architecture of the model (does the model allow for "awareness of the state of mind")