I may be teaching my grandmother to suck eggs but I have just come across intensive interaction and wow. I am reading Phoebe Caldwell's book "Finding me, Finding you" which is mainly about using intenisve interaction with autism, but there are other more general books out there. I've tried a couple of exchanges with ds1- and wow- he responded instantly. I think the main benefit (from reading the book), is that it reduces, stress, anxiety, and therefore self harming, and teaches the individual that there is a world out there that they can iteract with, and provides some connection.