Homework

Due in 6 hours. I suppose i should have started a little earlier. As it was, i just took a verbal laxative and let it all flow out... You can tell, i'm sure.

QUESTION 2: The Critical Period
One of the arguments for the biological foundation of linguistic knowledge is the notion of critical period. First, explain what is meant by critical period and provide examples from the natural world to demonstrate your point. Then explain how the notion has been expanded to apply to language and what kinds of arguments have been used to do so. Finally, give an evaluation of the validity of this argument in relation to language.

As the name implies, a critical period defines a limited window of time within which a certain event or chain of events must occur, and outside of which they cannot. When applied in the field of First Language Acquisition, as proposed by Wilder Penfield (1959), Steven Pinker (1994) and others, "critical period" refers to the idea that there exists in people's lives a time beyond which a native-like acquisition of language becomes impossible.

The implications of this concept will be elaborated and explored later in the paper. As an introduction to that, however, it is important to consider other natural processes, taking place in the animal world, which must be accomplished within a critical period. The fact that they are biological is fundamental to our analysis, because if an analogy can be established between them and the process of language acquisition, an argument can be made for the presence of an implicit, biologically based 'ability' for language in human beings.

As noted by Thorpe (1958), one very clear case of the existence of a critical period within which a capability must be "initialized" in the animal realm is that concerning the chaffinch's command of its singing. This bird, which is capable of producing a characteristic and very systematic song, will never properly perform it unless it hears it before reaching maturity. Likewise, as pointed out by Lorenz (1970), greylag geese can only be imprinted, and their imprinting changed, within the first 36 hours of their birth; after that, it becomes impossible.

Thus, although the susceptibility to being imprinted and the ability to sing a specific song are physiologically inherent in these creatures, it is apparent that both must be cued and stimulated during a certain, early period of their lives for the innate potentialities to properly manifest themselves. Other processes presenting these characteristics are the acquisition of binocular vision in children (Almli et al. (1987)), which fails to appear if not used between one and three years of age, and of the vestibular system, at least as far zebrafish go (Moorman et al. (2002)).

These facts, although they clearly attest that there are critical periods which bear on the manifestation or lack thereof of genetically coded capabilities in other animals and even in humans, do not directly prove the theory about the existence of such a period for language acquisition. Nevertheless, they serve as a point of analogy and make evident the fact that it is exposure and/or exercise of certain organs or innate abilities that determine their functioning or manifestation in later life.

Incontrovertible evidence for the existence of a critical period in language acquisition could be provided by a comparative study of adults who had been exposed to language at different stages of childhood and adolescence. If, regardless of environment, intensity of exposure and teaching methods, an inferiority in the language command of those who were exposed later could be detected, it would become very difficult to think of theories that accounted for this fact other than the critical period one.

Fortunately, language is such an undissociatable part of being human that most children are exposed to it from birth, in one way or another. So called feral children, who have been kept away from all human contact from a very young age, are very rare – only a hundred or so have ever been reported and, indeed, it has proven very difficult for them to acquire language. However, the isolation they suffered resulted also, almost invariably, in an inability to acquire other traits that are usually thought of as inherently human, like walking "properly", or in social behavior difficult to judge other than as impaired by any cultural standard. Whereas these facts might indicate that language is not the only process with cognitive associations that is sensitive to a critical period, often they have also served to cast doubts on the mental health of these children (Newton (2002)). Thus, it has been argued that the reason for their failure to acquire a proper command of language lies in innate brain defects, and not in an expired critical period. Nevertheless, it is equally possible to argue that, even if such children were to show differences in brain activity and/or development in the most modern medical tests, we would be hard pressed to say whether the damage was a birth defect or a result of failure to meet those critical windows with the appropriate input.

A case in point is that of Genie, who was isolated, restrained and punished if she made any noise until the age of thirteen and a half. Being the most recent and dramatic case of a feral child, mention of her is very common in all language acquisition literature that deals with the critical period theory. Although the same questions are pondered as to her possible brain defects, a particular fact about her allows us to finesse this discussion: Genie had practically no language at all when she was discovered, yet she soon learned many words, and began to string them together; however, these sentences were very short, and contained very gross syntax violations (Pinker (1994)). She never got past this stage. A similar case is that of Chelsea, who only at 31 got a hearing aid to compensate for her deafness. Though provenly normal at the emotional and neurological levels, she was never exposed to any form of language till then. And like Genie, although she quickly acquired a rich vocabulary, her syntax remained extremely bizarre (IDEM (1994).

The facts examined to this point support quite strongly the view that a critical period exists, if nothing else, for syntax acquisition. The human brain seems to include a 'skeleton' on which syntax is to grow, which must be exercised within a certain age. Other indications of it are found in the study of deaf children who begin acquiring sign language at a very early age from deaf adults who only acquired it in their teens (Singleton et al.(2004)). In these cases, the children are better able to absorb the correct grammatical rules and set parameters to the right value, even when they have no interaction with other second generation speakers. This means that when exposed to language at this age, but not later, they are able to pick right from the inconsistent input around them.

Even more revealing are those studies that have explored the transition from pidgins, which tend to be mere collections of vocabulary that do no have any organized grammatical order, into creoles, which do. Pidgins are usually created when adults that do not share a common language are thrown together and must find some means of communication, but the first generation of children that is born into a pidgin-speaking society (or, presumably, introduced to the pidgin within the critical period), almost instantly transform the haphazard collection of words into a creole, rich in grammatical rules and consistent with them. This happens whether the original pidgin is spoken (Bickerton (1992)) or signed (Kegl et al. (1989)), all of which indicates, once more, that children are "geared" to take advantage and be aware of syntax in ways that adults are not.

As for other aspects of language acquisition, such as phonetics and pronunciation, it seems that a critical window of exposure can also be assumed. For instance, it has been noted that, if s/he is exposed after a certain age, the speaker will always have an accent identifiable as non-native, whether s/he is a first or second language learner (Oyama (1982)).

Authors such as Pinker (1994) argue that if introduced to it after the age of six, children's ability to acquire a native-like command of a language, be it first or second, is compromised. If after puberty, normal first language acquisition is unexpected, and if the learner already possesses a first language, the new one will not be as perfectly known.

Personally, I am satisfied that, at least as far as the acquisition of syntax is concerned, there is enough evidence to speak of a critical period. I believe that this is the core of the argument, anyway. After all, the critical period theory, together with the poverty of the stimulus argument, are important mostly in that they support the idea of a Universal Grammar innate in all humans. In this sense, what is important is to prove the existence of a critical period for the first setting of the principles and parameters of a grammar. It may or may not be possible to fully reset those principles and parameters to accommodate a second or third language after a certain age, but this is not so relevant. The same goes for pronunciation, because if a critical period exists for the acquisition of it, this will point, in my opinion, to a set of innate capabilities different from those underlying UG