What I mean is like in photos, but I don't think I have the right terms nor knowledge to explain that 
. I believe there was a Weekly Challenge on that, and was looking for the winner's piece (can't remember by whom it's by nor its author, only that it was a cute little monkey), but I couldn't find it. Field of range I think it was called.
What he could do is have that effect and work on it in order to focus the piece on an element, for example the eyes, and everything around it slowly loses detail. That's what I mean.
Hope it's an interesting idea.
Focus for simple range, Depth of Field for breadth. It exists primarily in photography because not only is the human eye far more accomplished than a camera lens, but we are unable, in regular vision, to focus on the out of focus areas as we are when looking at a photograph.
In all, it's neat, but entirely cosmetic. the point of foundational skills is that they are what actually makes a piece work, and all the dithering and glazing and AA etc are only the icing on the cake. If the cake does not work, nobody cares about the icing.
