The research theme Crosslinguistic interaction investigates the dynamicity of language systems in bi- and multilingual speakers, especially in underexplored languages. The aim is to understand the underlying mechanisms that trigger interactions between the languages in contact not only in their lexicon but also in their respective phonetic/phonological domain, their morphosyntax, and discourse domains. The goal is to explain phenomena that are characterized by a shift in language dominance and subsequent changes in the languages in contact. To achieve this goal, the social and linguistic environment of speakers will be investigated and the combined impact score of various factors shaping this process will be established. This will advance the theoretical foundations of psycholinguistic approaches to multilingualism. It will also help to develop innovative methods and apply new experimental techniques.