时间：2022-06-18 03:14:42
【Abstract】Critical Period Hypothesis（CPH） was first introduced to second language acquisition by Lenneberg in 1967.Then it aroused many scholars’ attention. There are both affirmative and negative views.
【Key words】Critical Period Hypothesis； Second Language Acquisition； Affirmative views； problems
1. Researchers’ Studies on CPH in SLA
Johnson&Newport’s（1989） research explored the practical skills in grammar of 46 native Korean and Chinese speakers who arrived in America from 3 to 39. They had learned English for a period from 3 to 26 years. The result revealed that success in acquiring grammatical proficiency was almost predicted by the age when they first learn English and the proficiency seemed to decline at the age of 8 years old. This study appears to be widely cited as one of the best evidence of the CPH in SLA.
Birdsong and Molis （2001） conducted a replication of Johnson and Newport （1989）. The profiles of 61 native speakers of Spanish， 29 of whom had arrived in the U.S. by age 16 （early arrivals） and 32 of whom had arrived age 17 or above （late arrivals）. For the early arrivals， the average length of residence was 12.2 years whereas the average length of residence for late group was 10.5.Birdsong and Molis figured out that there was a strong inverse relationship （-.69， p
Dekeyser （2000） has carried out a research which has been intended to test the fundamental difference hypothesis. Through a study ofHungarian-speaking immigrants， he has demonstrated an explanation concerning exceptions which have failed to resonate with what critical period hypothesis has suggested. Moreover， Dekeyser （2000） has furthered shed light on the different learning mechanisms featuring young andsecond language learners， which can be attributed to the power of critical hypothesis
Singleton has shown doubts concerning critical period hypothesis in real earnest. In this very article written by Singleton （2001）， the author demonstrates a relatively detailed review of studies with regard to age factors on the basis of its historical development. In the same vein， Singleton has been devoted to research studies with persistence， in his relatively new work entitled “Age and SLA：Research Highways and Bye-Ways”， Singleton has adopted a critical perspective at Critical Period Hypothesis and concluded that the proposition at issue is far from being well-grounded upon reviewing relevant evidence favoring CPH.
2. Problems of the Critical Period Hypothesis
The most common error of the CPH in SLA appears to be an enormous emphasis on unsuccessfulL2 learners and the ignorance of the older learners who achieve native-like proficiency with starting learning L2 after a certain CP（Marinova Todd， 2000）. According to Krashen（1979）， natural comprehensible input can be regarded as the fundamental principle in L2 acquisition， and the ability to attain comprehensible input may increase with age. It may account for the success of those late starters in L2 who achieve native-like proficiency in the end. Next， other factors should be taken into account. Other variables such as length of stay in the country and differences between the L1 and L2 also had a significant influence on the results. Age was not the only variable that affected the results.
3. Conclusion
Previous studies can give us a lot of information but there are some limitations or problems of studies on the CPH. According to the newly studies， there are other factors that can influence the proficiency of the SLA， such as environment， input， interaction， output and so on. we need to make greater efforts to carry out more research studies concerning the effect of CPH so that we are able to gain a better insight into the research field.
References：
[1]Bialystok&Hakuta.In Other Words：The Science and Psychology of Second LanguageAcquisition[M].New York：Basic Books，1994.
[2]Birdsong&Molis.On the Evidence of Maturational Constraint in Second LanguageAcquisition[J].Journal of Memory and Language，2001（44）：235-249.
[3]Dekeyser R M.The Robustness of Critical Period Effects in Second Language Acquisition[J].Studies in Second Language Acquisition，2000（22）：499-533.
[4]Johnson&Newport.Critical Period Effects in Second Language Learning：The Influence of Maturational State on the Acquisition of ESL[J].Cognitive Psychology，1989（21）：60-69.
[5]Krashen S.Long M H.Scarcella R C.Age，Rate，and Eventual Attainment in Second Language Acquisition[J].TESOL.Quarterly，1979（13）：573-583.
[6]Marinova Todd S H.Marshall D B，Snow C E.Three Misconceptions about Age and L2 Learning[J].TESOL Quarterly， 2000.（34）：9-34.