The critical period is EQUALLY critical for signed languages as it is for spoken languages
August 25, 2019
There’s this common belief that, key to its development, spoken language must be acquired during a critical period. And that signed languages can wait. Absolutely false. What’s true is that language, whether signed or spoken, require natural input from birth and on for normal language development in either mode. Research by Moon, Lagercrantz and Kuhl in 2013 shows that babies are ready for language even before birth. This means that a child must be exposed to language during a very early age. During the first year of life and on, children are busy analyzing their linguistic input and forming hypotheses about how their language is structured. Even if they do not produce language itself yet, children are still figuring out patterns in their languages. If access to language is delayed during that first year, it can have seriously detrimental effects on a child’s later linguistic development. Four articles by Mayberry and Fischer in 1989, Mayberry and Eichen in 1991, Newport in 1990 and Emmorey et al in 1995, their research shows that for deaf adults who learn sign language later their development in that language, like the ability to express themselves, is impacted. Even if these deaf adults have been signing for many years, there’s still evidence that their skills do not match the language development of other deaf adults who have been signing since birth. Native or early-exposed signers demonstrate increasing fluency in their language while late-exposed signers often plateau. The main point here is that exposing a child to sign language early is not negative. Natural language acquisition can be achieved through signed language. This means that parents should be encouraged to include signed language as part of their communication with their deaf children. Even if parents make the decision to implant their children, spoken language can still be acquired even with access with signed language, which should be done as early as possible. Accessible natural language will blossom in the minds of deaf children.