Subject: Do the prelinguistically deaf think before they are taught language?

I am asking without being taught some language, are the prelinguistically deaf 
capable of thought? Like infants, are they capable of thought, just no means of 
expressing that thought? Or, are simply both not capable of thought but only 
instinct and habit? I hope that clarifies my question a bit more. We are all 
taught some form of language, and think in that language. The french think in 
french, the spanish think in spanish.... The deaf who know ASL or other forms 
of sign think in sign. WITHOUT being taught that sign, are they capable of 
thought? 

Re: Do the prelinguistically deaf think before they are taught language?