Is some part in one hemisphere the decision maker and "calling the shots" - controlling the opposite side's hand "directly" and controlling its own side's hand through the corpus callosum. Or: is there some "Gestalt" of parts in both hemispheres working as one making the decision?
If the latter - it would seem counter intuitive to have a deciding part which is not "unified" in one region, having to go back and forth through the corpus callosum for deciding.