According to Vygotsky, this is the beginning of thinking, this kind of dialog, and at this point, it's completely external. It's all happening in that space between the child and her mother, and only over time does it become interalized. And how that happens, Vygotsky thought, is that as the child gets older she'll start to take on the dialog herself; she'll start to talk to herself. This is the stage we call “private speech.” We've all seen kids do this, right? Where they narrate every single thing they're doing: “Put the ball in the box. Take the ball out of the box.”
Now what then happens is a few years further down the line, these kids who were narrating everything they were doing then go to school and the teachers tell them, “Shhh. Don't talk out loud.” So they get the message that they need to start doing this internally. So, they start to whisper to themselves out loud, and then they whisper to themselves silently because the words are now in their head. And that, according to Vygotsky's theory, that is thinking. Only then, he says, is a child having a thought.
The always-excellent Radiolab disccusses Lev Vygotsky's theory of Thought and Language with Charles Fernyhough in the Voices in Your Head episode.
This fascinates me for two reasons.
The first is that I have a son who is in the process of learning to speak. This is exactly what we do with him: talk to him about solving problems. I'm not sure I'm 100% convinced by Vygotsky's theory, though. It seems clear that George is thinking even when we're not talking him through problem solving. At least I suppose that's what he's doing when he's flipping through the pages of Byron Barton's Planes, but perhaps this isn't exactly what Vygotsky means by “thought.”
The second reason this is interesting is because of Steven Johnson's recent book Where Good Ideas Come From argues that good ideas come about when diverse ideas collide, such as in the coffee houses of the Enlightenment and Modernist Parisian salons. If Vygotsky is right, this may be because thinking begins—and to some extent remains—a social act.