Betty Edwards encountered the same problem when teaching students how to draw.
She made a still-life with a ball infront of a vase. But the student drew the ball beside the vase. When she said "Look the ball is in front", he replied "Yes but I don't know how to draw it that way."
Like the essay writer the student was trying to replicate symbols he had already practiced instead of seeing with fresh eyes. She gave the students an image upside down and they were able to replicate it accurately because it forced them to look instead of draw learned symbols.
http://www.amazon.ca/The-Drawing-Right-Side-Brain/dp/0874774241
Since Robert Pirsig put this very well, I’ll just copy down what he said. I don’t know if this story is based on reality or not, but either way, it’s true.