Species-Specific Behaviors in Sensitive Periods - Essay Example

According to Eric Lenneberg (1967), the ability to acquire a language within humans is an example of biologically restrained learning and could be acquired normally during a specific critical period. However, it has been shown by recent research that most of the critical periods reveal more regular offsets and more intricate interactions between experiential and maturational factors than was anticipated by the original perception of a critical period. In order to understand the concept let us examine language acquisition within humans.

Studies involving normal individuals have shown a strong association between the age of introduction to a language and the eventual proficiency acquired in that language (Newport & Johnson, 1989), although generally with much fewer excessive discrepancies in adult learning than those encountered in isolated children’s case studies.
During the early period of exposure, language learning may demonstrate a benefit for adult learners, especially in the attainment of vocabulary and the swiftness of utilizing specific complex forms of the sentence: nevertheless, long-term consequence distinctly favors those who initiate the language learning process during childhood. It has been seen that peak expertise in the language, in command over the grammatical structure and sound system, is exhibited by individuals who were exposed to that specific language during their early childhood. Such learners demonstrate flawless command over the rhythm and accent of the language as well as full control over the morphology and syntax.

The growing age of exposure results in a decline in mean proficiency, commencing as early as the 4 to 6 years age and progressing until proficiency levels for adults (Newport & Johnson, 1989). On average, the learners exposed, in their adulthood, to a language reveal poorer performance in various facets of the language, although individual fluctuation also enhances with age (Newport & Johnson, 1989), and some people may draw near the expertise of early learners (Birdsong, 1992).

These consequences have been presented for proficiency measures including accent level, production and understanding of syntax and morphology, grammaticality verdicts for syntax and morphology, and syntactic dispensation accuracy and speed as well as for both the second and first languages. It has been noticed that the age of commencing the first language has a substantial effect. On comparing the age of acquiring a first and second language, it has been found that the late onset of first language consequences in lower performance than the late onset of the second language no matter whether it is signed or spoken language. Moreover, during early childhood, only hearing a particular language that is not produced or heard again for several years, may consequence in picking up to enunciate that language as an adult with a relatively more indigenous accent (Au et al., 2002).

On the other hand, all facets of language are not impacted by the exposure age in an equal manner as the acquisition of semantic processing and vocabulary occur comparatively ordinarily in late learners. Therefore the language facets that are influenced by the critical period include morphology, phonology, and syntax. While among these facets, some are more while others are less contingent upon the exposure age. For instance, the fundamental word order is acquired by late learners relatively well, but more intricate grammatical aspects reveal strong consequences of late learning (Newport & Johnson, 1989).

The exposure age also impacts the language representation mechanism in the brain, with resemblances between the neural and behavioral effects. Functional magnetic resonance imaging (fMRI), Positron Emission Tomography (PET), and event-related potential (ERP) studies have shown that the left hemisphere is strongly activated for dispensing the native language, in monolinguals as well as bilinguals (Neville and Weber-Fox, 1996).

Taken together, these outcomes provide reasonably strong confirmation for a sensitive or critical period in learning the grammatical and phonological facets of the language and in coordinating the neural mechanisms for dealing with these arrangements in a proficient way. However, the existence of such critical periods for development is still under exploration. Read More