This paper considers cross-linguistic findings concerning the early development of formal, arbitrary, grammatical systems in normal hearing and deaf children and in children with congenital brain abnormalities. The paper reviews evidence showing an early acquisition of grammatical forms. Such learning is typically dissociated from the development of the relevant semantics. Form–function correspondences were not required for the development of morphological paradigms and for certain aspects of formal syntax. This finding held across all the populations studied.

It is hypothesized that the autonomous nature of these formal paradigms accounts for their priority in learning cross-linguistically.