Future research is necessary in order to determine the extent to which
even highly proficient bilinguals deviate from monolingual norms in their L1
and L2, and factors which impact such intra- and interpersonal variation.
Moreover, the relationship between proficiency levels in bilinguals’ L1 and
L2, and the increased cognitive load in bilinguals in comparison to monolin-
guals is a potential line of fruitful research.
The next section looks at the relationship between bilinguals’ two lan-
guages in early bilingual development.
Maturational Constraints in Bilingual Speech 37