Curiousness calling...
Take a barely verbal Autistic child with a short fuse and a negative and violent behaviours repetoire alter 1 aspect of his ordinairy routine and kaboom he's suddenly using signs and mouthing words [we're having a mute phase - will not raise his voice above a low whisper at the moment] and hasn't bittn, pinched or had a screaching hissy fit at anyone in days..
Can we safely conclude that its the one thing he was doing before causing the frustration and stupendously difficultto manage behaviour?