Abstract

The human communication system is unique among other species in displaying extreme variation. Every one of the extant ~7000 systems imposes an enormous and special learning task on infants. However, up to now, the acquisition process of only a few languages is properly documented. This means that research on language acquisition only captures a fraction of the learning challenges of the world’s languages. Theories of language acquisition, however, critically rely on generalizations of learning processes that hold across any differences in particular cases and thus provide insights into the faculty of language as property of our species. This is why we need to study and document the acquisition process of as many diverse languages as possible.

Since we are currently unable to document the acquisition process of a large number of languages we developed a sampling method to select languages that differ maximally in their grammatical features (Stoll & Bickel 2003). I will present the ACQDIV database that follows this principle (Stoll& Bickel 2003, Moran et al. 2016, 2020). It contains standardized acquisition data from 15 languages, allowing for cross-linguistic research. This allows us to simulate maximum variation exhibited in the languages of the world and test theories in extreme cases of language diversity. I will illustrate it’s cross linguistic applicability with a study of input-distributions. Then I will present how language acquisition can be documented in an ecologically valid way in non-WEIRD (Western, educated, industrialized, rich, democratic, Henrich 2010) circumstances in the field. I show the challenges and advantages of both longitudinal studies and cross-sectional studies and illustrate this with concrete examples from two studies, one on Chintang (Sino-Tibetan, Eastern Nepal) and one on Shipibo (Pannoan, Peruvian Amazon). I show how linguists and language acquisition researchers have been collaborating in this endeavour which hopefully will not only have an impact on the understanding of language acquisition but also will contribute to the documentation of human cultural heritage.

Linguistic interest in sign languages began in the 1960s and since then, more than 100 sign languages have been identified. Research studies on sign languages have looked at many aspects of sign languages including structure of signs, sentence structure, meaning, discourse, acquisition of sign languages, sign language in the brain, language contact and variation, etc.

While the studies have been mostly limited to a few sign languages, several features common across sign languages have been identified. In particular, certain properties arising due to the visual-manual nature of sign languages have been noted. These include a higher prevalence of iconic signs, and the use of non-manual expressions and space for grammatical purposes. In addition, some unique sociolinguistic phenomena such as village sign languages and code-blending have been observed.

In this talk, I will give an overview of various linguistic features of sign languages, with examples from Indian Sign Language, and also briefly discuss phenomena such as village sign languages and code-blending.