Continuing with our e-interview, Natascha Müller talks about delay effects in childhood bilingualism:

“Meanwhile, there is ample evidence for delay effects of early child bilingualism. Bilingualism can slow down the acquisition process with respect to age of acquisition and MLU; in other words, for some grammatical properties, bilingual children reach the adult norm later (age and/or MLU) than monolingual peers. There is also evidence which shows that delay effects are observable in balanced as well as in unbalanced children (Müller & Patuto 2009), which means that an uneven development of the two languages is not a prerequisite for delay. Furthermore, although unbalanced language development can slow down acquisition with respect to age, it does not necessarily lead to differences between bilinguals and monolinguals with respect to MLU in the weakly developed language (Müller & Pillunat 2008). It looks as if delay is related to complexity in the following sense: Language A and B exhibit different degrees of complexity for a particular grammatical property. In Hulk & Müller (2000) and Müller & Hulk (2001), complexity is defined as the coordination of information from different modules, pragmatics and syntax for example. Delay is indicative of target-deviant grammatical representations which, during the course of acquisition, have to be “corrected”. The child will use the less complex analysis of language A in relation to grammatical property X when using language A and language B. Müller & Patuto (2009) further refine the scenario for delay effects of cross-linguistic influence and conclude that in addition to complexity defined as the coordination of information from different modules, the surface strings of the two languages A and B have to be analyzable in terms of the syntactic derivation of language A (which is less complex). This prerequisite looks trivial at first sight, but it excludes the possibility that children come up with analyses for the more complex language B which are not also “supported” by the evidence from language B. Also, it makes the interesting prediction that if the more complex language B is acquired together with a language which encodes the respective grammatical property in such a radically different way than in language A (the less complex language), the derivation of language A would not be “supported” by the evidence of language B when used by the child while speaking language B.

 Delay is also interpreted as a default strategy adopted when the speaker cannot cope with the processing load of the grammatical phenomenon or the load created by the fact that two languages are being processed (Sorace & Filiaci 2006). The performance-oriented view of complexity assumes that it is the language with the more constraints for example which is the more complex one. In a recent article, Serratrice, Sorace & Paoli (2004) have studied subject omissions in early child bilingualism and have argued that cross-linguistic influence will go uni-directionally from the language with fewer pragmatic constraints in the distribution of overt pronominal subjects (English) to the language where the appearance of pronominal subjects is regulated by pragmatically complex (=more) constraints, such as topic shift and focus (Italian). The coordination of syntactic and pragmatic knowledge is a demanding task for young children in general (Avrutin 1999), and even more so in the case of bilingual children since they have to evaluate competing solutions to the syntax-pragmatics problem from two different languages. For the null-subject property, Serratrice, Sorace & Paoli (2004) predict that cross-linguistic influence will affect Italian, the more complex language.

 “Cross-linguistic influence will go unidirectionally from the language with fewer pragmatic constraints in the distribution of overt pronominal subjects (English) to the language where the appearance of pronominal subjects is regulated by pragmatically complex constraints, such as topic shift and focus (Italian). The coordination of syntactic and pragmatic knowledge is a demanding task for young children in general, and even more so in the case of bilingual children since they have to evaluate competing solutions to the syntax-pragmatics problem from two different languages.” (Serratrice, Sorace & Paoli 2004: 201).