The Debate on Maturational Constraints in Bilingual Development: A Perspective from First-Language Attrition

A controversial topic in research on second-language acquisition is whether residual variability and optionality in high-proficiency late second-language (L2) learners is merely the outcome of cross-linguistic transfer, competition, and processing limitations, or whether late learners have an underlying representational deficit due to maturational constraints on ultimate attainment in L2. This study argues that insights into this question can be gained by comparing advanced late L2 learners with late bilinguals who grew up with the language under investigation as their first language (L1), prior to emigrating to another country. The latter group, who use the language of the host country predominantly in their daily lives, typically exhibit increased optionality in their native language as a result of cross-linguistic transfer and L1 attrition. They do not, however, have a representational deficit in their L1, having acquired it monolingually during childhood. Such a comparison has the potential to distinguish grammatical features that are prone to bilingualism effects from those that natives can maintain but with which L2ers struggle persistently, possibly due to maturational limitations. This study compares 20 long-term attriters (English L2) with 20 highly advanced immersed learners of German (English L1) and 20 predominantly monolingual controls. The bilingual populations are matched for proficiency and for their use of German in daily life. The analysis comprises a group comparison and an investigation of individual performance, to assess whether there are L2 speakers who perform within the accuracy ranges of a larger population of attriters (n = 53) on all features, and similarly, whether any of the attriters perform within the accuracy range of a population of native controls (n = 53). The findings indicate that there are some areas of grammar (e.g., obligatory word order) where the L2 speakers are similar to the L1 attriters, and others (in particular noun phrase morphology) where attriters and monolinguals behave differently from the L2ers. This finding is interpreted as being consistent with an account that assumes some form of maturational constraint on language learning.