Child language acquisition: nature or nurture?
(final version)
The study of language development, one of the most fascinating human achievements, has a long and rich history, extending over thousands of years (Chomsky, 2000).

As the nature-versus-nurture argument is inevitable to arise whenever human behaviors are discussed, it is not surprising that language experts have debated the relative influences of genetics and the environment on language development (Hulit & Howard, 2002). Among the various proposals concerning the mechanisms involved in acquiring a language, two opposing theoretical positions, the behaviorist and the nativist, are the most prominent and influential ones (Ayoun, 2003; Garton & Pratt, 1998; Owens, 2001). Due to the indefinite explanation of the exact process, the continuous interest of the inquiring people, and the sheer significance of the precise result, the controversy remains ongoing and popular. In view of the more obvious limitations of the behaviorist interpretation and the prevailing contributions of the nativist interpretation, the latter one is more rational to accept.

Limitations of the behaviorist interpretation
As the name implies, behaviorism focuses on people's behaviors, which are directly observable, rather than on the mental systems underlying these behaviors (Narasimhan, 1998). Language is viewed as a kind of verbal behavior and it is proposed that children learn language through imitation, reinforcement, analogy, and structured input (Fromkin, Rodman ; Hyams, 2003).
Do children learn language through imitation?
Imitation is involved to some extent, of course, but the early words and sentences that children produce show that they are not simply imitating adult speech. Since there is an infinite number of potential sentences implied, children's complex and creative utterances cannot be explained by a passive response to the language of the environment.

In addition, imitation cannot account for common child language mistakes, which are highly unlikely to be failed imitations of what adults would say (Cattell, 2000).
Do children learn language through reinforcement?
Another proposal is that children learn to produce correct (grammatical) sentences because they are positively reinforced when they say something right, and negatively reinforced when they say something wrong. Roger Brown and his colleagues at Harvard University report that reinforcement seldom occurs, and when it does, it is usually incorrect pronunciation or incorrect reporting of facts that is corrected (Fromkin, Rodman & Hyams, 2003). In fact, attempts to correct a child's language are doomed to fail.

Children do not know what they are doing wrong and are unable to make corrections even when they are pointed out (Hulit ; Howard, 2002).
Do children learn language through analogy?
It had also been suggested that children put words together to form phrases and sentences by analogy, by hearing a sentence and using it as a sample to form other sentences. Nevertheless, problem arises constantly as, for instance, children who formulate a rule for forming questions, "move the auxiliary to the position proceeding the subject", will never move the first auxiliary of a relative clause on analogy (Meadow, 2003).
Do children learn language through structured input?
Yet, another suggestion, placing a lot emphasis on the role of the environment in facilitating language acquisition, is that children are able to learn language because adults speak to them in a special "simplified" language sometimes called motherese.

(Fromkin, Rodman ; Hyams, 2003). Controlled studies demonstrate that motherese does not significantly effective. Moreover, in many cultures, adults do not use a special register with children, and there are even communities in which adults hardly talk to babies at all (Cattell, 2000).
By emphasizing production, the behaviorist minimized comprehension and underlying cognitive process, which is superficial to some extent for it does not consider what the children bring to the learning task. As Owens (2001) has summarized, the magnitude of the failure of behaviorist attempt to account for verbal behavior serves as a kind of measure of the importance of the factors omitted from consideration, and an indication of how little is really known about this remarkably complex phenomenon.

Contributions of the nativist interpretation
In contrast with the behaviorists, the nativists claim that individuals are genetically endowed with a specific facility for language that is realized with minimal assistance from the environment (Garton ; Pratt, 1998). To better clarify the language acquisition development, the nativists have introduced two prominent and outstanding concepts: the universality of language among all human beings, known as universal grammar (UG), and the schedule by which it is required, regardless of cultural or other environmental variations, known as the language acquisition device (LAD).
A close look at the UG
One of the most compelling arguments for the nativist perspective is that language is essentially the same experience for all human beings, no matter what language they speak, where they are or how they interact with their models (Chomsky, 2000). As listeners and speakers of languages, we may be most impressed by their differences, but when languages are studied carefully, we discover many commonalities.

All languages have rules to indicate the structural relationships among words in sentences. All languages distinguish between subjects and predicates and allow the embedding of one sentence structure into another to create an elaborated sentence representing both original structures. All languages have rules to indicate changes in tense and plurality, and draw sets of speech sounds from a common pool of sounds, and the list goes on (Cattell, 2000; Hulit ; Howard, 2002; Owens, 2001). Of central importance is the fact that some form of languages is common to almost all human beings. Even humans with very limited mental abilities can communicate using simple conventional linguistic rules. Chomsky (2000) asserts that human languages differ only superficially but that underlying principles are more uniform.

All of the commonalities or linguistic universals are evidence that language is an ability humans possess, not by virtue of specific learning or teaching, but by virtue of their humanness (Hulit ; Howard, 2002).
A close look at the LAD
Since the rules of generative grammar is considered universal, it is a logical extension to assume that it must be an innate ability, that is, something everyone is born with. The nativists thus liken the child to be a LAD (Cattell, 2000). LAD, a hypothetical entity, receives primary linguistic input in the form of sentences of the language heard by the child, and produces, as output, grammatical sentences of the language (Garton ; Pratt, 1998). What goes on in the mysterious LAD? It might be regarded as a black box, wired to receive the language input data and to output or generate sentences.

In all cases, LAD is wired to produce a grammar of the language, capable of generating comprehensible sentences (Owens, 2001). Thus, grammar is the universal grammar, so is achieved by all children, regardless of the particular language community in which they are growing up. LAD also proposed to account for the assumed poor levels of language input children received, for it can deal with incorrect grammar and other irregularities of spoken language as the primary linguistic input (Garton ; Pratt, 1998). Children are not predisposed to learn any particular language; all are born with the same facility and will develop as native speakers of the language of the community into which they are born.

The child has innate knowledge of universal principles that govern the structure of language. These principles are resident in the mind of the child and are triggered by linguistic input (Hulit ; Howard, 2002).
These two major concepts of the nativists receive their strongest support from the observation that the grammar a person ends up with is vastly underdetermined by linguistic experiences. Although children hear many utterances, the language they hear is incomplete, noisy and unstructured, including slips of the tongue, false starts, no information as to which utterances are well formed, and so on (Fromkin, Rodman ; Hyams, 2003).

It is UG that helps children extract the rules of their language and to avoid many grammatical errors. Consequently, there is little doubt that human languages conform to abstract universal principles, and that the human brain is specially equipped for acquisition of human language grammars (Chomsky, 2000).
The investigation of how children learn language, like many other academic pursuits in that different theories that attempt to explain the phenomenon compete for acceptance (Owens, 2001). The behaviourists who hold the view that children, beginning their "language tanks" on empty, become language users as their tanks are filled by experiences provided by the language models in their environment, can hardly account accurately for the intricate process of language development (Hulit ; Howard, 2002). Instead, by assuming the children are equipped with an innate template or blueprint for language, the nativism is psychologically active and linguistically creative in successfully making up the inadequacies of the behaviorism.

Yet, we are still far from understanding the full nature of the principles of the UG. Therefore, in the future, more researches are needed to determine exactly which part of the language is innate and universal so that humans can further uncover the valuable mechanism.
( 1475 words; ave: 25; f-k: 12)
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