Well, if Mischel's right, the people trying to train these kids are screwed. Or maybe the kids with the wrong temperament just blow themselves up and solve the problem that way. :-)

I lean toward the self-governance idea primarily because the schools are ultimately trying to produce adults who can be trusted off the reservation, so to speak. There won't always be someone standing there with rewards and punishments, so while I do know the system has at least one rather severe punishment they deploy often enough for the kids to be scared of it, what they really need is for the kids to internalize and become responsible for their own control. The neurological example you describe sounds useful for that.