The part of the golf swing from beginning to impact, occurs in about 2 seconds with most of that time taken up by the backswing.  This means there's not a lot of time for conscious thought once the swing gets underway.  So, once the club is put in motion, what happens in the swing is dictated by what stimulates your reflexes.

     Imagine standing on a par 4 with trouble on the right and you've picked out a safe target down the left side and just as you take the club back, a picture of the ball going right pops into your head.  You either produce the shot you've just seen in your head or you feel your swing change while it's happening and the shot you hit is one that goes so far left, you're in as much trouble as you'd been had you hit it right.  In both these scenarios, your reflexes have taken over and directed your muscles to produce what transpired.

     Poor balance causes reflexive compensation.  The most glaring example of this phenomenon is the reverse pivot or reverse weight shift.  Reflexes prevent a proper weight shift in the backswing.  If a poorly-balanced golfer were to force a weight transfer in the backswing, he/she would more than likely be unable to stay in place long enough to hit the ball.  Reflexes take over to keep the golfer centered and because the club, arms and shoulders move to the rear, the weight moves forward as a counterbalance.  And in the forward swing, because the weight is already forward, it shifts in the opposite direction.

     Most of what you feel happening during your swing are effects of reflexive motion.  What happens can be very subtle or very glaring.  In most cases your attention is so focused on hitting the ball, it's not until it's over that you're left with the sensation that "that didn't feel right".
Once again, there are slight variations from one touring professional to the next, but you won't see them stray too far from this position.  When you do, you'll also notice them straying from the top of the money list.
"The less skilled the player, the more likely he is to share his ideas about the golf swing."
Reflexes
"The game of golf is 90& mental and 10& mental."
"Since bad shots come in groups of three, a fourth bad shot is actually the beginning of the next group of three."
"When you look up, causing an awful shot, you will always look down again at exactly the moment when you ought to start watching the ball if you ever want to see it again."
"There are two things you can learn by stopping your back swing at the top and checking the position of your hands:  how many hands you have and which one is wearing the glove."
"A ball you can see in the rough from 50 yards away is not yours."
"If you want to hit a 7 iron as far as Tiger Woods, simply try to lay up just short of a water hazard."