There is ample evidence that bilingual children’s morphosyntactic systems can influence each other. Despite the vast number of studies on such cross-linguistic influence it is unknown whether the languages of bilingual children can influence each other during real-time sentence processing (online). The central aim of this thesis is, therefore, to investigate whether cross-linguistic influence occurs online in bilingual children using a self-paced listening and eye-tracking experiment. This thesis also investigates whether surface overlap and language dominance – factors that have been argued to predict cross-linguistic influence in children’s speech production and offline comprehension – are related to cross-linguistic influence online. Furthermore, this thesis examines how online cross-linguistic influence develops into adulthood.
The results of this thesis show that the languages of bilingual children and adults influence each other during real-time sentence processing. The amount of influence is modified by surface overlap and language dominance. First, online cross-linguistic influence was found to be more pronounced in situations in which the word order of children’s languages partially overlapped rather than completely. Second, the more dominant children were in the language not in use, the stronger cross-linguistic influence became. Our results suggest that bilingual children’s languages are both activated during sentence processing. As a consequence, children have to inhibit the non-target language. This inhibition is visible in children’s sentence processing speed and their online sentence interpretation. In order to account for these findings, we propose a model on cross-linguistic influence in sentence processing (CLISP).