linguistic analysis - Professor Binkert's Webpage - Oakland University

Evidence for Cerebral Lateralization
First, stimulation of the speech areas of both the left and the right hemispheres of the brain during
neurosurgery produce spontaneous vocalization in young children; however, in most adults, only
stimulation of the speech areas of the left hemisphere produces spontaneous vocalization.
Second, anesthetization of both the left and the right hemispheres of the brain produces a cessation
of linguistic function in children; however, in most adults, only anesthetization of the left hemisphere
produces a cessation of linguistic function.
Third, removal of either the left or the right hemisphere in young children to excise a large invasive
tumor has the same effect on native language acquisition. Generally, the remaining hemisphere takes
over language functions and children recover well. Removal of the left hemisphere of an adult,
however, generally interferes grossly with language function.
Fourth, studies using magnetic resonance imaging (MRI) find that brain activity in the left
hemisphere during the production of speech increases with the age of the child.
Fifth, studies of brain injury show that cerebral lateralization occurs. Trauma or disease can result
in the loss of linguistic function. The condition is called APHASIA. The older individuals are, the
more likely they are to experience aphasia if the left hemisphere is involved in the injury.
Evidence for a Critical Period for Native Language Acquisition
First, children must be exposed to a language before they reach puberty to acquire a native language.
If they are isolated so that they do not hear a language, they may never be able to learn one.
Second, intellectually disabled individuals can make progress in acquiring language up to puberty;
after that, progress is slow and difficult.
Third, the closer to age two that hearing-impaired children are fitted with hearing aids, the more
language they are exposed to and, consequently, the more enhanced their language development is.
Fourth, sudden acquired deafness, as might result from a condition like meningitis, has a profound
effect on language the younger the affected individuals are.
Fifth, the acquisition of a second language becomes more like native language acquisition the
younger the acquirer is. In other words, in America, it would benefit children if they were exposed
to foreign languages in elementary school or before.
All the evidence above points to a biological and maturational basis for native language acquisition.
Thus, regarding theories of language acquisition, we will take a largely rationalist approach. At the
same time, we must account for variation. As we have seen, speakers do not always share the same
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