Terry, you beat me to it. Instinctive IS aiming.
Late one afternoon I was shooting two judo arrows at cans in the back yard. One arrow was light colored and the other was stained dark. As the light failed, I began to hit much better with the light colored arrow, and that little light went off in my brain. Although I wasn't consciously aiming with the arrow, obviously I was doing just that.
Since then, ALL of my hunting arrows (well, except for turkey arrows) are light in color, because most shots come at low light times.
That's not to say that I have to see the arrow to shoot well. Another day, while shooting inside the arrow shaft plant, there was a power failure just after I had made my first shot of a series at 20 yards. On a whim, I kept shooting (no one else was there), even though there was no light at all. I could hear the arrows hitting the target, but couldn't see anything but the image left in my mind when the lights went out. When the power came back on, all of my arrows were grouped with the first one.
Like zetabow said, powerful tool the brain.