A subject advantage in covert dependencies: the case of wh-questions comprehension in French Sign Language
Résumé
Who is a native signer? Since around 95% of deaf infants are born in a hearing family, deaf signers have access to a sign language at various moments of their life, and not only from birth, and the lin-guistic input they are exposed to is not always a fully-fledged natural sign language. In this situation, is it the notion of native signer as someone exposed to language from birth of any use? We report the results of the first large scale cross-linguistic investigation on the effects of age of exposure to sign language. This research involved about 45 Deaf adult signers in each of three sign languages (LIS, LSC, LSF). Across the three languages, participants were divided into three groups: those exposed from birth, those between 1 and 5 years of age, and those exposed between 6 to 15 years of age. We report the results of a battery of tests designed for each language investigating various aspects of lex-ical and morphosyntactic competence. In particular, these tests focused, beside lexical comprehen-sion, both on those morphosyntactic phenomena that are known from the spoken language literature to be good detectors of language impairment or delay (i.e., wh- interrogative and relative clauses) and on morphosyntactic phenomena that are sign language specific (i.e., role shift and directional verbs). Our results showed a clear effect of being native in the morphosyntactic competence, with significant differences across language and tests between signers exposed to sign language from birth and those exposed in the first years of life. This confirms the life-long importance of language exposure from birth and the reliability of the notion of nativeness, at least for syntax. On the other hand, while in most domains the differences observed between populations might be differences in performance, for some specific constructions signers belonging to the three groups may have different grammars. This latter finding challenges the generalized use of native signer’s grammar as the baseline for language description and language assessment.