I think the next topic I would like to read up on is the development of language. I know this has been studied extensively, from both the perspective of speech therapy and that of the function of the brain's speech centers, but I don't know whether it has been examined as an indication of the development of consciousness.
I thought of this while listening to my 3 1/2 year old grandson chattering on about what "Yossi" wants and what "Yossi" is doing. It's not that he's lost the ability to use pronouns; he also chatters about what "I want" and what "I do." I think that when he refers to himself in the third person he is asserting his role as an actor in the world, that his "I" is not only a point of view from which he considers the rest of the world but is, simultaneously, a boy called Yossi who eats and plays and takes part in the community.