Explore the Effect of a Critical Period on Second Language Acquisition

Critical Period Hypothesis:

Critical Period (CP) refers to a specific and ‘fixed’ or invariant period of time during which an organism’s neural functioning is open to effects of external experiential input. To be specific, there are three important essentials in this conception. Firstly, this developmental period is biologically determined; the onset, end and the length of the critical period are invariant, which is the consequences of some internal clock that keeps time independent of what happens during the window of time. Second, the environmental input can affect the organism during this invariant period, while the system cannot be altered by external stimulus any more beyond the critical point. Third, the lack of adequate input during the critical period can result in permanent deleterious consequence for the bio-behavioral system (Werker & Tees, 2005).

Lenneberg (1967) proposed Critical Period Hypothesis (CPH) for the language development by examining abundance of behavioral and neurological evidence (Johnson & Newport, 1989; Du, 2010). There are four vital components in this hypothesis. To be specific, (1) the remarkable offsetting point of achieving ultimate language attainment like native speakers is around puberty (Hyltenstam & Abrahamsson, 2000); (2) either first or second language requiring fully development must occur within the period between birth and the onset of puberty; (3) the ultimate competency of language acquiring beyond CP could not be comparable to that of language acquired during within CP (Sakai, 2005); (3) the CPH focused on age restrictions on the possibility of reaching native-like levels of the target language instead of the age restrictions on the ability to acquire a language in general (Hyltenst...

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