A sensitive period for second language acquismon: A reaction-time study of grammaticality juooments of English by Korean-English bilinguals

This study was conducted to provide answers to the following questions related to the sensitive period hypothesis in second language acquisition: (1) Does a sensitive period exist in SLA? (2) If so, what characterizes the period? (3) Can the sensitive period be explained by age or by confounding affective factors? (4) What grammatical categories are most affected by age? For this purpose, 60 Korean speakers of English were tested for their ability to judge the grammaticality of 96 English sentences in 12 grammatical categories, employing a reaction-time procedure. These subjects first began learning English at ages varying from 0 to 29 years and each had spent a minimum of five years in the United States. Statistical tests were conducted on three dependent variables: RT, error rate in the RT task, and error rate in an informal test. The findings suggested that a sensitive period exists in second language acquisition, particularly in terms of sentence-processing speed (automaticity), as evidenced by uniformly faster performance by early-learner L2 groups than by late-learner L2 groups. However, no definite evidence was found for such age effects regarding accuracy. Although early-learner L2 subjects as a group surpassed late-learner L2 groups in their accuracy, accuracy was found to be related more to length of stay, rather than to age of onset, and thus the possibility cannot be ruled out that the age effects observed were due to the confounding effects of length of stay. The observed sensitive period was characterized by a gradual decline around age nine. It was also shown that if one starts to learn an L2 within the sensitive period, he/she can achieve native-speaker-like L2 proficiency, but that if one starts to learn an L2 outside the period, he/she might not be able to achieve such L2 proficiency. Age of onset itself, not affective factors, is apparently the factor underlying the assumed age-related limitations in second language acquisition: None of the affective factors except motivation (in the case of accuracy in a non-timed situation) correlated with the dependent variables and the combined affective factors had no power to predict the ultimate proficiency of L2 subjects. Finally, age effects were more clearly manifested in certain grammatical categories, so these categories presented more difficulties to late L2 learners than other categories. The study fulfilled its purpose by providing some interesting answers to the questions raised about the sensitive period in second language acquisition. Additionally, it was found that even early L2 learners can never be exactly like native-language learners in L2 performance simply because they are bilingual and, although they might be able to improve their L2 accuracy given extended exposure to L2 input and/or strong motivation, they probably cannot attain L2 processing speed.

Name thesis:degree_name

M.A.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Teaching English as a Second Language

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

1991

Author dc:creator

• Kim, Ryonhee

Contributors dc:contributor

• Mack, Molly

• Teaching English as Second Language
• Sensitive period hypothesis
• Second language acquisition
• Grammatical categories
• Age effects

Statement dc:rights

• Copyright owned by the author.

Language dc:language

eng

Handle dc:identifier

https://hdl.handle.net/2142/125894

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/125894