In the second place, Critical Period Hypothesis (shorten as CPH) is another fresh linguistic theory introduced from the biology to explain the SLA study results “the earlier, the better” that sociology, physiology, psychology and linguistics manifested。 As an interdisciplinary conception, critical period is defined as “a period of time in a life circle which has a greater sensitivity to the stimulation of surrounding environment than any other time”。 This theory in biology refers to the stage that environment would play the biggest role in the process of inpidual development。 Therefore, from the broad sense, critical period can be applied to all aspects of human beings or other animal behavior while from the narrow sense, in the linguistic field, the so-called critical period refers to “some special phase of life development in which people can acquire a language promptly and effortlessly, without external intervention or teaching”。

At the present time, English education represents a low-aging tendency in China。 Even though some practitioners may repute that situation is well found because it is grounded on the theoretical foundation called Critical Period Hypothesis that Lenneberg proposed, so far, scholars have been still under intense discussion on this hypothesis for decades without a verdict。 This topic of argument is so controversial that relevant researches have sprung one after another, opposite parties haggling over。 With repeatedly laying stress on the importance of CPH, researchers have tried to prove the existence of the critical period and have thoroughly explored the best starting age for SLA。 Further investigations of these issues are beneficial to provide educators with inspiration that they can attach importance to offer educatees timely guidance。 In that way, the popularization and promotion of second language could accomplish multiplier effectiveness。 Therefore age issue is extraordinarily significant to the setting of second language education policies and courses。

This paper is pided into five parts。 Part one is the introduction, in which the background of the research, the definition of the Critical Period Hypothesis and the value of the research are introduced。 Part two involves experts’ studies of the research。 Part three talks about some theoretical introductions of CPH。 Part four introduces means, results and analysis of the investigation。 Part five is a conclusion and some advice based on the previous parts。

2。 Literature Review

Lenneberg is the first one who advanced the conception of Critical Period Hypothesis in 1967。 Although Lenneberg raised this theory with regard to native language acquisition, it generated immense dispute。 Subsequently researchers found both animals and human can be living examples to prove the existence of CPH。 Here are several foreign examples。 

For one thing, there is a distinguished testimony in biosphere。 In 1987, Gould’s research implies adult male Pine Buntings possesses certain notes, which can automatically trigger collection devices in the brains of male Pine Buntings。 Only if they hear the ululation from adult male Pine Buntings within 40-50 days after birth, can they tweet afterwards。 Even if they hear the ululation beyond this period, they are not competent to chirp。 In this case, it is 40-50 days after birth that constitute the critical period of male Pine Buntings’ chirping behavior (Gould 156)。

For another thing, there are three human instances to testify the existence of critical period。 Supporters of CPH acknowledge their research is the most authoritative one。论文网

Firstly, in the early 1970s, an American girl called Genie was imprisoned for 12 years since she was born 20 months later by her tyrannical father。 During this period, she could neither hear nor watch TV and she made little conversation with her parents。 She was found until she was 13 years old, lack of language ability。 In spite of experts’ rendering her 7-year language training, Genie performed worse than children under the same age。 She could not use articles, synonyms, auxiliary verbs and verb tenses。 As a result, she still spoke sentences with syntax errors (Curtiss 1977)。 Genie’s illustration comparatively directly provides evidence that the critical period is truly present in language acquisition。 For all that, on the grounds of analogous documentations’ insufficiency, nobody can allege her sluggish inpidual language development was due to missing the critical period other than inpidual cognition or emotional defects。 In contrast, what can attest this view is that if some children were born to suffer hearing loss whereas they grew up in a wholesome environment and then regain hearing after puberty, still facing serious difficulty when they study language。  关键期假说实证研究(2):http://www.youerw.com/yingyu/lunwen_85070.html