critical period

Through extensive research, there has been strong evidence for the hypothesis of a critical period for the acquisition of language, and that this is not an all or nothing phenomena. In the article by Johnson and Newport (1989), they assessed the age of acquisition of a second language by examining Chinese and Korean immigrants, and separated them into age specific categories. This allowed them to examine their hypothesis that second language acquisition follows the same critical period as first language acquisition. They concluded that second language learners exposed to the second language by age 7 could acquire the second language with the same proficiency as native speakers of that language. They also demonstrated that there is a asymptotic digression of proficiency for second language as a function of age of exposure. Similar findings been replicated in American Sign Language (ASL) learners, since there is a large age range when deaf people acquire ASL as their first language. In many exhaustive studies of language acquisition by Helen Neville and colleagues, she has demonstrated ERP evidence that supports Johnson and Newport's findings of second language acquisition. With all of the evidence supporting a critical period for language acquisition, what factors in development determine the deficits in language proficiency after the critical period? Is there a biological neural correlate or environmental factors that inhibit the ability to fully understand what causes the deficits in language learning? Referenced in Johnson and Newport's article is the study by Hubel and Weisel of ocular dominance column formation in the visual cortex, and the critical period for its development. In their experiments they showed that dominance columns form within a specific time period, ONLY of there is asymmetric input to the visual cortex, but if the cats were raised in a dark environment (eyes sutured shut from birth) that the critical period could be delayed long after the normal time window, with normal vision developing after opening the eyes. This adjustment of the critical period hasn't been shown in the development of language. So what determines the deficits shown in language mastery in late learning of language? Combining evidence from other studies, and studies of different cognitive modalities, it appears that there is some genetic neural basis for a language critical period. Genie, a girl confined for her early life, with minimal human contact and minimal language exposure, showed severe deficits in language proficiencies. She was able to acquire new words after rescue, but with severe syntactic deficits. Since visual information reaches the V1 region, and is then sent to other areas of the brain, it is essentially a more simple system than the many systems involved in language comprehension, and production. Should we assume that there is an absolute critical window for language that is a result of neural changes globally in the brain that are involved with language acquisition, or only certain regions involved in language abilities. I feel that the latter is a better hypothesis. For instance, Genie is able to produce words without impediment, and can link words into a meaningful statement, but she is unable to link the words together in a tense specific, grammatically correct manner. This leads me to conclude that the cortical region(s) involved in syntax, are primarily linked to a critical period. This is evident in Johnson and Newport's findings as well. I have personal anecdotal evidence that supports this hypothesis. In grade school, we studied basic Spanish words (i.e. counting, greeting, basic vocabulary), but did not study any of the semantics of the language. In high school, I learned many more words easily, and studied without becoming proficient, the syntactic components of Spanish. I still have a large Spanish vocabulary, but like Genie, I make gross syntactic errors.

This research has a strong social/environmental component that is not being addressed. Are adults living in a community that uses their non-native language, that are attempting to acquire the language, are being inhibited through stereotyping and overt discrimination? Is the language barrier between them and those who they interact with to gain exposure to the second language resulting in avoidance of communicating, thus they receive less exposure than children who generally don't have as much exposure to stereotypes, and prejudice? Johnson and Newport attempted to determine if self-consciousness was a factor in their learning. After reviewing the methods of their research, there may be a cultural confound in their research, because the questioning doesn't appear to be in terms that would be culturally accurate for native Asians. It would be advantageous to conduct an assessment of this with the assistance of a culture expert to develop culturally significant questions to see what role stereotype/prejudice plays in second language development in adults.