The relation of foreign (or second) language learning to child language acquisition constitutes an interesting and important issue. If the two are essentially similar, then it must be concluded that foreign language learning, like native language acquisition, is a natural process, one that cannot be taught as such but rather that will occur, under the right circumstances. On the other hand, if there are fundamental differences between acquiring a first language and learning a second, then perhaps teaching is possible and methods should take such differences into account.

There are a number of indications pointing to a close relationship between foreign language learning and native language acquisition. We have just observed that the most successful foreign language learning occurs under the conditions of extensive exposure to a language in a context where the language serves as the primary means of communication and when learners possess integrative motivation. All of these factors are present, so far as can be determined, for children acquiring their native language. Furthermore, error analysis reveals that many of the errors made by foreign language learners, as they utilize their approximative systems, are similar to errors made by children. Overgeneralization, incomplete rule application, universal difficulty factors, all play a role in both native and foreign language acquisition.

 Despite the undisputed fact that many adults fail to master another language, it must be noted that some adults do succeed, even under less than ideal circumstances. This indicates that children’s basic capacity for language acquisition is not lost as they mature. Perhaps the capacity is more difficult to activate, or maybe it is simply more difficult for adults to attain the necessary environment to activate their capacities. In any case, foreign language learning is possible for adults.

There are several factors by which adult language learners differ from children, including the following:

• Adults have already mastered one language and therefore they know a large number of linguistic forms and rules.
• Adults’ nervous systems and the muscles of their vocal tracts are accustomed to transmitting and carrying out instructions for particular sets of phonetic features.
• Adults have acquired certain strategies for learning new materials. They rely more on explicit explanations than does the child and may be somewhat less capable on induction, that is, of reaching generalizations on the basis of particular data.
• There is some evidence that adults can make changes in their native language system (dialect changes, for example) only by adding extra rules; it is possible that this imitation affects foreign language learning.
• Adults know a great deal about properties of meaning and the world.

None of these factors exists in children learning their native language. For the adult, foreign language learning is both easier and more difficult than native language learning is for the child. It is easier in that adults are knowledgeable about the world and about language, and this prior knowledge may permit concentration on the task of language learning; children must divide their attention, mastering not only language but other types of knowledge as well. Thus, under the proper conditions, adults can succeed in becoming rather fluent speakers of a foreign language in a year or two; no child attains equivalent linguistic control of his or her native language in such a short period of time. But language acquisition is more difficult for an adult, for many adults have an accent even after prolonged contact with and use of the foreign language. Each of the factors listed above as characteristics shared by adults but lacking in young children, contributes to the adult’s success or failure in learning a foreign language.

Neurophysiological research has demonstrated that an individual’s brain reaches a mature, adult state at approximately the age of puberty, that is, at roughly twelve years of age. It is precisely at this point in life that many people begin to experience increased difficulty in learning a foreign language, and it is not unreasonable to ask whether the maturation of the brain is somehow directly related to language learning ability. There is no firm answer to this question at the current time; too little is known about the brain and how it functions. Whatever the relationship between the brain and the ability to acquire a foreign language, it is clear that brain maturation does not cause loss of that ability. If it did, no one would ever be able to learn a foreign language after the age of twelve or thirteen.

Some readers may have observed in the text a distinction between acquisition and learning.  Children are described as acquiring their native language, whereas adults are said to learn a foreign language. This distinction is a common one. Acquisition is viewed as a natural, unconscious, untaught, and probably unteachable process, while learning is somewhat artificial, usually conscious, and possibly dependent on instruction and study. The distinction has been preserved in this discussion since there is relatively little conclusive evidence that foreign languages can be acquired naturally by adults, but such evidence is increasing as research proceeds. Soon, linguists and language specialists may refer to foreign language acquisition, just as today they discuss child language acquisition. 

Julia S. Falk