Conscious & Unconscious Multitasking

Why we are poor at talking on the phone while driving:
We are already and have long been multitaskers, in other words, we just do it (so well) unconsciously, not consciously. It is conscious multitasking (talking on the phone while driving) that we are so bad at because of the limits of conscious attention, but multitasking per se — we are built for that. As we gain skills those skills require less and less of that conscious attention so that an expert such as Michael Jordan, or today, Kobe or Lebron, can consciously plot his strategy for weaving through a maze of defenders down the court because his limited conscious attention is no longer needed for dribbling, body movements, head fakes, and so on. Driving a car requires incredible multitasking at first but is soon much less difficult because the multitasking 'moves downstairs' and out of the main office, over time.

From here.