In this Sinergia study we propose to track young single and dual language learners’ linguistic, socio-emotional and metacognitive development in social context. We will investigate these processes longitudinally with three- to six-year-old children in Switzerland and Germany. We are a team of interdisciplinary collaborators working in linguistics, education, and developmental and cognitive psychological science based in two countries with three societal languages. Each local research group contributes state-of-the art paradigms, diagnostic procedures, and methods from their field to establish a common general model of single and dual language learning in the social context. The results are intended to be generalizable across countries, languages, and contexts.

            The collaborative research design focuses on four samples at each site of the participants (Basel, Bern, Neuchâtel, Würzburg), each with n = 188 three- and four-year old single and dual language learners (N_total= 750). Children will be assessed seven times at regular intervals over 3.5 years. The samples of dual language learning children, two-thirds of each subsample, will include learners of Turkish and Italian as home languages, who are learning (or are about to learn) the societal languages French, Swiss German or Standard German. The research design will allow us to assess dual language learners’ verbal and non-verbal dispositions and abilities by using culturally fair items and testing in the children’s preferred languages. This sophisticated design was successfully piloted in a preparatory/pilot study, confirming that our task construction and recruitment plans are feasible. Each research group will jointly investigate six intriguing topics, each with research questions that challenge current paradigmatic views about dual language learning. The topics are:

Modeling the variability of single and dual language learning

• Single and dual language learning as onecontinuous variable
• Dual language learning and developmental language disorder

Child-external and child-internal conditions of dual language learning

• Dual language learning in early education
• Socio-emotional adaptation and dual language learning
• Systemic cross-linguistic interference and transfer in dual language learning
• Metacognition and dual language learning

We envision that the newly generated evidence will have the potential to inform social policy and to impact early education practice in our globalized and multilingual societies