音声による外国語導入の臨界期に関する覚書 A Note on the Critical Period for Effective Introduction of a Second Language in a Naturalistic Setting
This paper suggests a critical period for a child to gain the most out of a second language classroom conducted in a naturalistic setting. The idea is initially formulated upon the author's observation in July 2002 that the 6th graders' responses were noticeably worse than the 5th graders' in the Iwaki elementary school English project. The age they began English is hypothesized to be a crucial factor differentiating the two groups, since they have been exposed to English for the same period of time. A few research studies and documented observations are drawn from three fields, namely, language acquisition, skill development, and developmental psychology. The limited review of the knowledge in the related fields points to around age 9 as the latest to introduce a child to a second language in a target-language-only classroom, if the plasticity of the child's brain and other functional capacity is to be fully utilized.
富山県立大学紀要 13, 70-74, 2003-03-31