The Influence of Age Factors on Second Language Acquisition

Abstract: In second language acquisition, age factors has always been the study focus and one of the most controversial issues of linguistics. Based on the Brain Plasticity Theory and the Critical Period Hypothesis, the purpose is to prove such a hypothesis that the younger the learner who begins to learn a second language, the greater the probability that he or she will achieve a native-like command of it.


The Definition of Second Language Acquisition

In order to investigate and understand the factors of second language acquisition (SLA for short), it is important to establish clearly what the meaning of the term “SLA” is. SLA refers to the subconscious or conscious processes by which a language other than mother tongue is learned in a natural or a tutored or a classroom setting; it covers the development of phonology, lexis, grammar, pragmatics, and other knowledge. There are two distinctions concerning the definition of SLA that need to be attached great importance so that what positions researchers have taken up in order to study how an L2 is learned will be clear. Firstly, it is very important to make a distinction between the terms “second language”, “foreign language” and “target language”. Technically, learning a second language takes place in a country where the language is widely used while leaning a “foreign language” takes place in a country where it is not an everyday medium. For example, when the English language is learned by a learner whose mother tongue is Chinese in the United States, it is called a second language; when learned in China, it is called a “foreign language”. The term “target language” simply refers to that language being learned, whether as an L2 or a foreign language. Secondly, second language acquisition is also sometimes contrasted with second language learning by some researchers especially Krashen on the assumption that these are different processes. The term “acquisition”, they think, refers to picking up an L2 through exposure, whereas the term “learning” refers to the conscious study of an L2.

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Age Factor in Second Language Acquisition

Age has been most frequently used in discussions of differences between kids and adults in SLA. This is partly due to the ease which it can be measured, unlike other general factors. Another reason is probably the commonly held belief that kids are better language learners than adults. SLA researchers often regard puberty as the critical point for acquisition, which refers to the stage of adolescence, usually from 13 to 15 years old. In Lenneberg’s study of biological foundations of language, subjects are divided into six grades according to age stage: 0 to 3 months (emergence of cooing)

  • 4 to 20 months ( from babbling to words)
  • 21 to 36 months (acquisition of language structure)
  • 3 to 10 years ( grammatical refinement and expansion of vocabulary) 11 to 14 years ( foreign accents in L2 learning)
  • Mid-teens-senium (SLA is increasingly difficult).

He also notes that foreign accents become likely in SLA around puberty, and SLA becomes increasingly difficult around post-puberty.

General Theories of Age Factors in SLA

Brain Plasticity Theory

In the study of SLA, Brain Plasticity Theory of Penfield and Roberts is often used as a biological basis for explaining the phenomenon that the younger the better in L2 learning. The notion of “plasticity” comes from a study of aphasia kids who suffer from partial or total loss of the ability to articulate ideas or comprehend or spoken or written language, resulting from damage to the brain caused by injury or some diseases. It refers to the way the brain can reorganize itself by shifting functions from one brain area to another after damage, at least during childhood. The theory suggests that the little kid’s brain has a cellular receptivity to language acquisition.

This receptivity may be a function of cellular plasticity or elasticity which is controlled by a sort of biological clock. With age, the biological clock changes the cellular plasticity, which reduces the organism’s capacity to learn the language. Penfield and Roberts predict that an optimal age period for L2 learning is between 4 and 8 because of greater brain plasticity.

Critical Period Hypothesis

The notion of “critical period” closely connecting with “plasticity” for language acquisition is a period, somewhere in childhood or at puberty, after which leaning language becomes markedly more difficult. First proposed by Lenneberg in 1967, the Critical Period Hypothesis predicts that “younger is better”, complete acquisition of speech can occur only before the end of neurological plasticity, and speech acquired after this event will be acquired more slowly and will be less successful. He notes that the age at which persistent aphasic symptoms result from left-hemisphere injury is approximately the same age, around puberty, at which “foreign accent” became likely in SLA. Researchers differ over when this period comes to an end. A particularly convincing study made by Johnson and Newport suggests that the period ends at about age 15. grammaticality judgment was tested in a large group of subjects who had immigrated to the United States at different ages. When they were tested around a decade after their arrival, a clear decline in abilities starts in people who arrived as early as the age of five.

Age and Second Language Acquisition

Comparison between L1 Acquisition and SLA

Many scholars and researchers always investigate a kid’s first language learning to know some useful information about their circumstances of second language learning. SLA always stands in contrast to L1 acquisition. A child, born without any mental retardation and physiological deficiency, can naturally pick up the full mother tongue in a natural environment. The acquisition of an L2, however, is not as effortless and successful as that of mother tongue; though many people learn an L2, few, if any, manage to go gain knowledge of the L2 equivalent to that of the L1, unlike L1 acquisition where virtually all kids acquire full L1. researchers have tried hard for many years to follow in the footsteps of L1 acquisition research, both in its methodology and in many of the issues that it has treated, aiming at providing valuable implications to SLA. Knowing how kids acquire an L1 and what the similarities and differences are between child L1 acquisition and SLA will surely, to some extent, benefit SLA.

Differences between L1 Acquisition and SLA

Ellis claims the differences between child L1 acquisition and SLA in a detailed way.

  • Feature
    • L1 acquisition
    • L2 acquisition
  • Overall success
    • Kids normally achieve perfect L1 mastery
    • Adult L2 learners are unlikely to achieve perfect L2 mastery General failure variation
  • Affective factors
    • Not involved
    • Play a major role in determining the success

Chomsky’s Universal Grammar (UG) may serve as a possible explanation of why SLA is less successful and more effortful than an L1 acquisition by distinguishing the different mind states. It argues that L1 children start with the zero states and go on to the steady-state; progress from an initial state of knowing only their innate endowment to a final state of knowing everything about a particular language. L2 learners, however, already know the first language; they possess one instantiation of UG which is distinguished by Chomsky as Si (which contains one grammar and is complete with principles and actual parameter settings). In this case, L2 learners start with the initial state which includes zero states and starts state already and goes on to the terminate state. The explanation of different mental states implies an age-related problem. Including zero states and start state, Si implies a late L2 learning instead of an early one. A Chinese baby who is sent into the United States when he or she is not physically old enough to be able to acquire the mother tongue, 10 months old, for example, has a great possibility to easily acquire perfect mother tongue from parents as well as perfect English from his or her peers and the society. The initial state, in this case, can also be referred to as zero states, because the L2 learning begins before L1 is acquired. The reality that bilingual children and adults, whose first and second languages are equally perfect, irrespective of the small number, indeed exist suggests, at least, that the SLA can be successful when it begins early enough. It is therefore not surprising that those people who are born in multi-language places and countries speak more than one language equally well. In Canada, many people speak English and French; in Hong Kong of China, the majority can speak English, Chinese mandarin as well as Cantonese which is quite different from mandarin in phonetics, way of writing characters, and sometimes in sentence structures.

Similarities between L1 Acquisition and SLA

The first similarity is the acquisition order. Ellis claims the similar routes of L1 and L2 acquisition in this way: “ SLA and L1 acquisition both involve transitional competence and, as might be expected, this is reflected in similarities, which are not total but nevertheless are strong, between both the acquisitional routes and the strategies that are responsible for them.” Whether SLA shares common characteristics with children L1 acquisition is not easy to prove with evidence mainly because of the most confounding factor—age. As Brown points out, age brings about differences in the physical, cognitive, and affective domains of learners. However, as we shall see later, it is better to learn an L2 early than late. In other words, there is indeed a sensitive period in the acquisition of both the mother tongue and the L2. As predicted by Lenneberg, it is hard to learn an L2 after puberty due to crucial brain maturation being complete, and individuals who are forced to acquire an L1 after a sensitive period should be equally unable to. Supports most frequently quoted for the critical period are the case studies of the children who had been isolated from language and who tried to acquire the language before and after their critical period. One typical example was a deaf-mute child named Isabelle, who was found at the age of six and a half. She spent alone in a darkened room before being found, but she succeeded in her language learning because she started learning before the critical period came to an end. Another example is a modern wild child named Genie whose abusive father had her isolated and physically restrained day and night in a small bedroom with little light and virtually no stimulation form the age of 20 months until she was 13. after this, Genie was hospitalized and treated for malnutrition, and her opportunities to socialize and learn language began. She had been beaten for making any noise in the period of isolation, so she was virtually unable to vocalize when she was found. Over the next four years a linguist named Susan Curtiss, was able to observe the development of her language and test how it related to her brain activity. Int many ways, such as phonological sounds, intonation patterns, two-word phrase combination, question production and so on. Genie’s language development was different from that of normal children, although she certainly acquired a substantial number of linguistic rules.

The Similarities between Children and Adults

Firstly, both children and adults lack an English-speaking environment because they learn English in China mainly through classroom instructions. Chinese is their daily medium to communicate with others including the teacher, classmates, friends, and parents. They cannot regale themselves on the accessibility of acquisition brought by the linguistic environment. In other words, both cannot naturally pick up English as immigrants do in the English-speaking country. Secondly, both are influenced, positively, and negatively, by the mother tongue. According to Universal Grammar, L2 learners already know the first language; they possess one instantiation of UG. That is to say, they start learning English from the initial state of mind, which already contains a Chinese grammar, and is complete with principles and actual parameter settings. Or, to make matters more complicated, children of very small ages may be learning English while the learning of Chinese is still incomplete; in this case, Si contains a non-final form of Chinese. The initial mind state, therefore, implies that both children and adults undergo more or less the influences caused by similarities and differences between English and Chinese in their acquisition of English.

The Differences between Children and Adults in SLA

In general, children differ from adults in many aspects of SLA. A child’s language is simple, with basic syntax, a small lexicon, and few grammatical endings on words. The adults, on the other hand, must translate the new language into all the complexity of his or her first language, including very complex structures and an extensive vocabulary. The young child can learn an L2 with less interference caused by the L1. One of the possible reasons for this is that the pre-school age child has an incomplete L1 acquisition. There are also a significant number of developmental, cognitive, motivational, and social factors that explain why second language acquisition is so much easier for a child.


Age is always an important factor in explaining the differences between children and adults in SLA; also the phenomenon that children usually outperform adults in the effort can be explained by the age factor. Whether an L2 is learned naturally in everyday life in a linguistic environment like an English-speaking country or by formal instructions in a non-linguistic environment like a domestic classroom, children and adults do share both Chinese similarities and differ greatly in many aspects. As learners of English, children, and adults learn the language in a non-English-speaking environment in similar order and are influenced in the acquisition by the mother tongue positively in case of similarities between the two languages and negatively in case of differences. Their development to cognition also differs greatly in many aspects ranging from physical and to attitude and motivation. Age is also a factor that influences the use of teaching methods. Children prefer a more relaxing and play-like environment to study L2. They are highly motivated by the methods that make them play and move about. Its advantages over the traditional methods are verified by an experiment showing that the students who had been taught by the active method gained a higher average score than those who had not. Other methods such as story-telling, singing songs, and games are also favorable to children’s L2 learning.


  1. Brown, R. A First Language. Cambridge, [M]. Mass: Harvard University Press,1973.
  2. Ellis, Rod. Understanding Second Language Acquisition. [M]. Oxford: Oxford University Press,1985.
  3. Ellis, Rod. The Study of Second Language Acquisition. [M]. Oxford: Oxford University Press, 1994.
  4. Lenneberg, E. Biological Foundations of Language. [M]. New York: Johe Wiley and Sons, 1967.
  5. Peccei, J.S Child Language. [M]. London: Taylor& Francis Limited, 1995.

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The Influence of Age Factors on Second Language Acquisition. (2016, Jul 19). Retrieved from