This theme covers a whole series of topics related to language, many of which can only be fruitfully addressed by interdisciplinary research. Worldwide there are at least 6,000 different languages, many of which have not yet been described. Although there are some similarities between all natural languages, for instance, all languages have consonants and vowels in their phoneme inventories and distinguish between words to refer to objects (nouns) and actions (verbs), there is a lot of variation as well. It is generally assumed that the neurocognitive processing of linguistic functions works similarly for all speakers and all languages, but cross-linguistic, experimental evidence from non-Western languages is extremely scarce, and discussions continue about the nature, or even presence of the universal basis of all languages.
While every normally developing child automatically acquires a language, the general processes guiding language acquisition are still hotly debated. Also, the majority of all speakers speak more than one language, i.e. most speakers are bilingual or even multilingual, certainly in a multilingual society such as Europe. However, very little is known about the processing and representation of a second language in the mind of the speaker. These and other issues are addressed in the LIBC hotspot Language and Cognition focusing on "Cognitive Neuroscience of Language: multi-linguistic, cross-linguistic and cross-system approaches".
Leiden University has a strong tradition in language-related research, ranging from the production and perception of speech sounds to comprehension of written texts and from developmental to evolutionary questions. It involves several groups in both in the Faculty of Humanities, in particular various researchers in the Leiden University Centre of Linguistics (LUCL), and the Social Science Faculty. In the Department of Educational Studies, for instance, Prof. Paul van den Broek focuses on developmental aspects of language learning, including reading and language comprehension.
In the Department of Psychology, particularly in the section Cognitive Psychology, several researchers (incl. Prof. Niels O. Schiller, Dr. Wido La Heij, Dr. Fenna Poletiek, Dr. Ingrid Christoffels) investigate language processing in natural and artificial languages, and bilingual language processing. Furthermore, in the Faculty of Sciences, there is a group investigating the similarities and differences between human language and communication systems in animals, especially some bird species (Prof. Carel ten Cate). In the Leiden University Medical Centre (LUMC), researchers are focusing on language development in children with severe hearing impairments who received a cochlear implant (Prof. Johan Frijns). Researchers from all these groups take part in this LIBC theme. A "Language and Cognition Group" (LACG) has been established since 2007 (http://www.languageandcognition.nl/lacg/) meeting every two weeks to discuss current research projects, new results, as well as plans in progress.