Um ano:


Fonte: http://static.hsw.com.br/gif/elimination-communication-1.jpg

(Elbers (1982); Vihman e Miller (1988) .
- Elbers, L. (1982) “Operating principles in repetitive babbling: a cognitive continuity approach”. Cognition 12: 45–63.
     -     Vihman, M. M. e R. Miller (1988) “Words and babble at the threshold of lexical acquisition”. In M. D. Smith e J. L. Locke (eds.) The emergent lexicon: The child's development of a linguistic vocabulary. New York: Academic Press.