Studies of preverbal infants exposed to a bilingual environment have unveiled the existence of important similarities, but also significant differences in the way monolinguals-to-be and bilinguals-to-be solve the problem of language acquisition. In this paper, I review these studies and I argue that some apparent bilingual failures are the…

Studying human development involves describing, explaining, and optimizing intraindividual change and interindividual differences in such change and, as such, requires longitudinal research. The selection of the appropriate type of longitudinal design requires selecting the option that best addresses the theoretical questions asked about…