Language ordinarily emerges in young children as a consequence of both linguistic experience (for example, exposure to a spoken or signed language) and innate abilities (for example, the ability to acquire certain types of language patterns). One way to discern which aspects of language acquisition are controlled by experience and which arise from innate factors is to remove or manipulate linguistic input. However, experimental manipulations that involve depriving a child of language input are impossible. The present work examines the communication systems resulting from natural situations of language deprivation and thus explores the inherent tendency of humans to build communication systems of particular kinds, without any conventional linguistic input. We examined the gesture systems that three isolated deaf Nicaraguans (ages 14–23 years) have developed for use with their hearing families. These deaf individuals have had no contact with any conventional language, spoken or signed. To communicate with their families, they have each developed a gestural communication system within the home called ‘‘home sign.’’ Our analysis focused on whether these systems show evidence of the grammatical category of Subject. Subjects are widely considered to be universal to human languages. Using specially designed elicitation tasks, we show that home signers also demonstrate the universal characteristics of Subjects in their gesture productions, despite the fact that their communicative systems have developed without exposure to a conventional language. These findings indicate that abstract linguistic structure, particularly the grammatical category of Subject, can emerge in the gestural modality without linguistic input.After reading the paper, I couldn't help but feel that while the data is interesting, it doesn't speak to the issue of innateness. Because the home sign systems were developed in collaboration with family members, it is entirely possible that those family members naturally include at least some of their grammatical categories in their signing, and thus that their deaf family members picked it up from them. Maybe I'm missing some aspect of the data, however, not being a linguist. If you're interested in language acquisition, check out the paper, and if you see something that argues against my interpretation, let me know.
Tuesday, February 07, 2006
Innate Grammatical Categories Evident in Home Sign?
A paper from an issue of PNAS from late 2005 argues that evidence of the existence of the grammatical subject in deaf Nicaraguan users of "home sign," which is sign language used in the home, but not based on official sign languages, and generally developed with no other linguistic input, is evidence of the innateness of the grammatical subject category. Here is the paper's abstract: