Cognitive theory does not provide a complete account of language development.
It is a partial account only. For example, it cannot account for the fact that there
are acquisitional sequences which are immune to instruction (Ellis 1990, p.182).
Instruction cannot change the order in which certain developmental structures
are acquired. Thus the basic assumption of cognitive theory, namely that language learning is not different in kind frolll other kinds of skill learning, is not
fully justified.