Proprioception

Defined: The perception of one's body parts in relation to space and each other.

An amazing tool. One that we take for granted it seems. In The Man Who Mistook his Wife for a Hat there is a story about a woman who loses proprioception. She loses her feeling of having a body, and in order to move body parts she has to look look at them and focus her attention on them in that way. In order to look at a body part, she first has to find it. For instance her hands may move wanderingly around without her noticing, and if she wants to walk, she first has to find her feet.

An amazing story, and a very disconcerting idea for someone who loves to dance. Although the movement-through-sight idea could be an interesting starting point for some choreography.