Abstract:

Age factor in Second Language Acquisition has always been a controversial issue. This paper tries to analyze the different performances, advantages and disadvantages in phonetic, syntactic, semantic and pragmatic acquisitions by comparing the characteristics of children, adolescent and adult learners in Second Language Acquisition, and to explore the relationship between second language learners and the age, and the “optimal age” in second language learning. Combined with the characteristics of learners at different ages in social-psychology, cognitive ability, affective factor and neurology, this paper puts forward different strategies for learners at different ages so as to grasp the different critical periods in Second Language Acquisition, which will help language learners get better achievements.

Keywords: Second Language Acquisition; age factor; Critical Period Hypothesis

摘要：

二语习得中的年龄因素一直以来就是一个值得争议的问题。本文将通过对比儿童、青少年和成人三个年龄段的学习者在二语习得中的特点，分析他们在语音、语法、语义和语用习得等方面的不同表现及优势与劣势，并结合不同年龄段的学习者在社会心理、认知能力、情感因素以及神经机能等方面的特点，探究学习者年龄因素与二语习得的关系以及二语学习的“最佳起始年龄”，从而针对不同年龄段的学习者采取不同的学习方法，把握二语习得不同的关键期，使二语习得取得更好的效果。

关键词：二语习得；年龄因素；关键期假说

1. Introduction
Second Language Acquisition, as a new discipline, is still relatively young. It refers to the process of learning a second language consciously or unconsciously that learners are under the condition of nature or guidance. In this field, age factor has become one of the most controversial factors that influence the Second Language Acquisition.  In 1967, Lennerberg proposed the “Critical Period Hypothesis”, then many scholars and researchers in the fields of applied linguistics, psychology, psycholinguistics and so on began to do a plenty of researches and experiments to prove whether critical period exists in Second Language Acquisition or not. Debate over the “CPH” has never stopped.