My memory isn't all that great, so I hate to go out on a limb here, but what I think was discussed in GEB was that if shown a sensible board layout that could be reached in real play, the pros could nail it in five seconds, whereas normal people could do only tolerably well in five seconds. Show the pros a nonsense board that could never come up in real play, and the normal people do the same as they did before, but the pros crash and burn. This is meant to show that the mental conception of a board is different between a pro and a novice.