The longitudinal study of the bilingual acquisition of DGS and written German presented in the following sections aims to contribute to our understanding of the development of a multilingual competence in deaf learners. By focusing on the structural competences attained in either language and on the range of language contact phenomena produced, the study seeks to provide further insights into bilingual deaf learners’ acquisition of a sign language and an oral language.
Acquisition scenario. Language acquisition in bilingual deaf learners, as we learned in previous sections, is determined by a complex interplay of internal and external factors that determine access to and accessibility of the two languages. Variation in age exposure to a fully accessible language marks a fundamental difference between language acquisition in this population vis-a-vis language acquisition in other situations. Further, we have seen that questions concerning the status of the written language need to be addressed in order to ascertain the status of this language in the bilingual development of deaf children. Following current assumptions we hypothesise that written language can be acquired without or with only limited access to the spoken language it relates to. As for metalinguistic awareness, often regarded as a requisite in this endeavour, we assume that it also develops and is further refined as a result of written language development. On a more general level we understand that the assignment of L1 or L2 labels to the languages acquired by deaf learners needs to be conceived of in a flexible manner. This is also reflected in a flexible conception of the language acquisition situation of bilingual deaf learners as it shares characteristics of bilingual first and child second language acquisition. Owing to the specific circumstances that determine this type of bilingualism we consider neither label as adequate to fully capture the characteristics of this acquisition situation.
Organisation of multilingual knowledge in deaf learners. Against this backdrop, the question arises as to whether current assumptions about the organisation of multilingual knowledge and language contact hold equally of the bilingual development of sign bilingualism in deaf learners.
- (a) Developmental trajectories. Firstly, with respect to developmental trajectories in either language, are they also characterised by structure-building processes as it has been found to hold for language acquisition in different acquisition situations? To date, only little is known about the bilingual development of a sign language and an oral language in deaf learners. Studies on sign language acquisition in native deaf learners have provided insights into some of the main milestones in the development of a sign language, but the picture continues to be fragmentary. As for bilingual deaf learners’ acquisition of the oral language, developmental studies are virtually non-existent. With respect to the developmental asynchrony between the two languages, the more advanced knowledge of sign language is often taken for granted, whereby assessments are seldom based on empirical data. Another fundamental question pertains to the development of the written language with no or only limited access to the spoken language. Is it also characterised by structure-building processes?
- (b) Role of language contact phenomena. Secondly, the sophisticated combination of elements of two distinct grammars in mixed utterances has been found to indicate that bilingual learners know, by virtue of their innate language endowment (i.e. UG), that grammars are alike in fundamental ways. This (tacit) knowledge is assumed to constitute the basis for the pooling of resources in the course of the bilingual development. In the acquisition of a sign language and an oral language, deaf learners acquire two languages that differ in their modality of expression. Does this difference affect the organisation of a multilingual competence? Research on bilingual deaf learners has provided some evidence that sign bilingual learners pool their linguistic resources, and that this can be taken as an indication of their (tacit) knowledge that languages are alike in fundamental ways. From a developmental perspective, the question arises whether cross-modal language contact phenomena are also developmentally constrained. In other words, are these phenomena related to the structural development in both languages?
Taken on the whole the issues that arise in relation to the bilingual development of deaf learners boil down to the question of whether they also pool their linguistic resources in a creative manner as it has been found to be the case of bilingual learners in other acquisition situations.