Keith Johnstone talks a lot about space (between actors and humans in general) in Impro. How it's essential to acting that you maintain the "correct" space as it's essential to normal human interaction.

I was reminded about it in Sandra Blakeslee's interview in which she talked about body maps in our brains and how the body maps extend to the objects we hold and to the space outside of our body that we think we occupy. So we nowadays actually know about the neural mapping to this concept Johnstone was talking about.

(Of course the space we think we occupy is a dynamic concept based on the context. Ie. in a crowded bus we settle for less space than in empty street and so on.)