Quote from logic_man:
I would think these activities engage two different parts of the brain, so, yes, that would mean that you could excel in one and not the other.
One thing you need to make sure about your "helper" is that the person you choose has to be OK with standing up to you after a losing trade and will be wiling to follow your trade rules even when there is a drawdown. If you are friends with this person, that could complicate things because you'd naturally be second-guessing them and they would want to please you by getting out of trades when you started to get nervous. I can see it potentially not making much of a difference.
But, to eliminate these potential problems, why not just automate your system?