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Chapter 10 Brain and Language
We wonder how the human acquire and use language. Research on the brain in humans and nonhuman primates, anatomically, psychologically, and behaviorally is helping to answer the questions connecting the neurological basis for language. This chapter will discuss these two areas of linguistic research─ neurolinguistics and psycholinguistics.
The brain is divided into two parts (called cerebral hemispheres), one on the right and one on the left. In general, the left hemisphere controls the movements of the right side of the body, and the right hemisphere the movements of the left side. There has been a basic assumption that it is possible to find a direct relation between language and the brain, and a continuous effort to discover direct centers where language capacities (competence and performance) may be located.
Franz Joseph Gall put forth theories of localization, that is, that different human abilities and behaviors were traceable to specific parts of the brain. The two specific parts of the brain related to language are Broca’s area (the front part of the left hemisphere) and Wernicke’s area (the back portion of the left hemisphere). They are two key areas of the cortex related to language processing. Language, then, is said to be lateralized. Lateralization is the term used to refer to any cognitive functions which are primarily localized to one side of the brain or the other.
Aphasia is the neurological term used to refer to language disorder that follow brain lesions caused by a stroke, a tumor, a gunshot wound, or an infection. Patients with Broca’s aphasia exhibit impaired syntax and speech problems, whereas Wernicke’s aphasia patients are fluent speakers who produce semantically empty utterances and have difficulty in comprehension.
3. Jargon aphasia: Patients may substitute words unrelated semantically to their intended messages; others produce phonemic substitution errors, sometimes resulting in nonsense forms, making their utterances uninterpretable. Aphasic patients who become dyslexic after brain damage are called acquired dyslexics because prior to the brain lesion they were normal readers (unlike developmental dyslexic who have difficulty learning to read).
This “tip-of-the-tongue” (TOT as it is often referred to) phenomenon is not uncommon. But if you never can find the word you want, you can imagine how serious a problem aphasics have. Aphasics with such problems are said to suffer from anomia.
2. “The corpus callosum” is between the two brain halves consists of two million fibers connecting the cells of the left and right hemispheres. When this pathway is split there is no “communication” between the “two brains.”
3. Persons with split brains have been tested by psychologists, showing that the two human hemispheres are distinct. The right hemisphere does better than the left in pattern matching tasks, in recognizing faces, and in spatial orientation. The left hemisphere is superior for language, for rhythmic perception, for temporal-order judgments, and for mathematical thinking.
The experiment shows that the left hemisphere is not superior for processing all sounds, but only for those that are linguistic in nature. That is , the left side of the brain is specialized for language, not sounds.
3. We know that the ability to hear speech sounds is not a necessary condition for the acquisition and use of a language from the study of born deaf humans who learn sign languages. In addition, the lateralization evidence from brain damaged deaf singers shows that the brain is neurologically equiped to learn language rather than speech.
Idiot savants show disability in certain spheres, but they demonstrate remarkable talents in others. The classic cases include superb musicians, or artists, or draftsmen but lack the simple abilities required to take care of themselves. Most of the savants have been reported to be linguistically handicapped.
They may be good mimics who can repeat speech like parrots but show meager creative language ability. Such cases strongly argue for domain specific abilities and suggest that certain talents do not require general intelligence, but they do not respond to the suggestion that language is one ability that is derivative of general cognitive abilities.
There is a dramatic case about a twenty-nine-year-old “linguistic savant” named Christopher. He has a non-verbal IQ between 60 and 70, and he is unable to take care of himself. Yet, when given written texts in some fifteen or sixteen languages, he translates them immediately into English.
He learned them either from speakers who used the languages in his presence or from grammar books. The investigators of this interesting man conclude that his linguistic ability is independent of his general conceptual or intellectual ability.
(2) Subjects also do better if the words occur in grammactically meaningful sentences as opposed to grammactically anomalous sentences; identification of words in ungrammatical sentences produced the most errors. This supports the idea that subjects are not responding simply to the input word by word.
(3) When subjects hear recorded sentences in which some part of the signal is removed and a cough substituted, they “hear” the sentence without a missing phoneme. This indicates that context plays a major role in determining what sounds the subjects replace.
2. Bottom-up processes: moving step-by-step from the incoming acoustic signal to semantic interpretation, building each part of the structure on the basic of the sensory data alone.
The reason why the first sentence is called a “garden path” sentence is because we are incorrectly led to interpret the word raced as the VP verb. To interpret the sentence correctly we have to retrace our processing until we know that the main sentence verb is fell.
