The "aim small, miss small" principal for instinctive archery states that you should aim for the smallest possible point.
In this picture you can see that there are a lot of "bullet holes" (more like arrow holes =) ) in the kill. You can choose one and absolutely concentrate on it.
However, what to do if you've a pretty new target? One with no bullet holes? Also, you are too far away to see differences in the fur etc.
How do you concentrate on the smallest possible point on a solid surface?
For example imagine this target:
Let's say we are about 40 meters away. You'll only see a solid brown surface from the shooting point.