I'm sorry Lizzie if I sounded in any way arrogant about my Aspergers niece; it wasn't intended I assure you. I can see that the condition manifests itself in many ways and to many different degrees. Actually, my niece sometimes self-harms by cutting her arms and punching herself. This could I expect be a parallel action to biting. It's sheer frustration and a stress/alarm response. She has recently had a change in her medication which has helped, and my sister is slightly less worried about her. It's a very difficult condition, but luckily more publicised and better understood than formerly.