Investigating age e ects on ultimateattainment in second language acquisitionCatherine

The Critical Period hypothesis and its successors have been widely tested in relation to Second Language Acquisition. This paper presents a brief review of some of the research ndings, and concludes that the jury is still out on the extent to which age correlates inversely with ultimate attainment in a second language. It suggests that there is too much evidence of high achievement amongst adults to attribute decline in proociency to age, and proposes instead a selective age eeect which may leave syntactic knowledge more intact than other language levels. This paper attempts to review some of the evidence and the theoretical motivation for justifying investigating age as a continuing factor in ultimate attainment in second language acquisition after the onset of puberty. Most of the work done on age eeects on ultimate attainment | as opposed to language learning ability | has focused on diierences between child and adult learners and on the origins of these diierences. It tends to be centred on discussion about the Critical Period Hypothesis (CPH) and maturational approaches. What I would like to do is see if a case can be made for examining age eeects in relation to diierential achievement amongst non-native speakers who have arrived in the second language community at diierent ages during adulthood. Lenneberg's version of the Critical Period Hypothesis (1967) proposed that primary language acquisition was connned to the period between 2 and 14 years of age: language acquired after puberty was a matter of semi-linguistic communication strategies using central cognitive processes. It was the plasticity of the immature brain that allowed language to develop: after hemispheric lateralization, the dominant left hemisphere took over language functions. Clearly, a major problem with the end of the Critical Period Hypothesis relates to evidence. Subsequent biological and linguistic investigations, notably by Krashen (1973) and Curtiss (1977) | on the case of Genie | suggested that there is no abrupt shutdown of rst language learning capacity at around 14: a `weak' version of the CPH suggests a `sensitive' period after which learning is possible but irregular and incomplete. The rather strict relation between lateralization and language learning proposed by Lenneberg has been undermined by the discovery that lateralization seems to be complete long before puberty | perhaps soon after birth. The latest study is of`Alex', who had no speech and 163