With proprioception, the brain plans out the movement before the person decides to do a certain action, and has the position of body parts relative to the brain on hand (to speak colloquially). There is a case where a person who lost his proprioception couldn't move his body without spending a lot of his time in physical therapy, and even after that, he could only walk so long as he was looking at his feet and was consciously working to place one foot in front of the other. 

So, it could work like that, or it could work like another case, where someone thought they had a really long neck, like from Alice in Wonderland.