The majority of people in the modern world speak more than one language, and as many as two thirds of children are being raised in multilingual environments. Across Europe, the proportion of multilingual children is currently around 20-25%, and steadily increasing. The last decades have witnessed a remarkable increase in effort from several disciplines aimed to uncover the mechanisms of language acquisition and language processing, and to understand how language is organised in the mind. One important aspect of this enterprise is the study of whether and how multiple languages interact within multilingual minds. However, this question is difficult to address within current methodological approaches which compare the linguistic behaviour of bilingual children to that of their monolingual peers. In this project, we propose a new methodology which will enable us to disentangle these two factors. We will go beyond comparing bilingual children to monolinguals by carrying out a comparison across multiple bilingual populations. In doing so, we will keep one language - the target - constant and vary the second language parametrically (based on the presence and absence of certain grammatical features). We will match the participants by their exposure to the target language, thus making sure that the only difference between the groups is their second language. This means that if we find any differences in the way the bilingual groups comprehend or produce the target language, we will be able to confidently attribute these differences to the influence coming from their second languages. The findings of the project will have major implications for theoretical models of languages in the mind, and for theoretical and practical aspects of language learning.
MuMin will use three methods: i) production experiments, ii) visual world eye-tracking to investigate online processing, and iii) detailed background questionnaires to match the participants by exposure to the target language. A large team of national and international researchers have been assembled to provide the necessary expertise and breadth required by the research questions.