As I may have mentioned my son is autistic and at 4 years old has never said a word. I believe that he has a wonderful visual memory because it took him no time at all to learn the paradigm behind PECS and he really does not care what symbol we choose for something as long as we are consistant.
Monday we brought home a test Assistive Communication Device, it is an ipod in a bombproof case with speakers and Proloquo loaded. He absolutely loved it, and has already figured out how to use it. The only problem is that he is trying to talk .... he makes sounds and points at his mouth when he wants something. So his inherant laziness is forcing him to talk rather than go get the device.
Either way we are better off than we were at this time last year.