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The language module or language faculty is a hypothetical structure in the human brain which is thought to contain innate capacities for language, originally posited by Noam Chomsky. There is ongoing research into brain modularity in the fields of cognitive science and neuroscience, although the current idea is much weaker than what was proposed by Chomsky and Jerry Fodor in the 1980s. In today's terminology, 'modularity' refers to specialisation: language processing is specialised in the brain to the extent that it occurs partially in different areas than other types of information processing such as visual input. The current[ vague ] view is, then, that language is neither compartmentalised nor based on general principles of processing (as proposed by George Lakoff). It is modular to the extent that it constitutes a specific cognitive skill or area in cognition. [1] [2] [3]
The notion of a dedicated language module in the human brain originated with Noam Chomsky's theory of Universal Grammar (UG). The debate on the issue of modularity in language is underpinned, in part, by different understandings of this concept. [4] There is, however, some consensus in the literature that a module is considered committed to processing specialized representations (domain-specificity) [5] [6] in an informationally encapsulated way. [6] [7] A distinction should be drawn between anatomical modularity, which proposes there is one 'area' in the brain that deals with this processing, and functional modularity that obviates anatomical modularity whilst maintaining information encapsulation in distributed parts of the brain. [8]
The available evidence points toward the conclusion that no single area of the brain is solely devoted to processing language. The Wada test, where sodium amobarbital is used to anaesthetise one hemisphere, shows that the left-hemisphere appears to be crucial in language processing. [9] Yet, neuroimaging does not implicate any single area but rather identifies many different areas as being involved in different aspects of language processing. [10] [11] [12] and not just in the left hemisphere. [13] Further, individual areas appear to subserve a number of different functions. [10] [14] Thus, the extent to which language processing occurs within an anatomical module is considered to be minimal. Nevertheless, as many have suggested, [15] [16] modular processing can still exist even when implemented across the brain; that is, language processing could occur within a functional module.
A common way to demonstrate modularity is to find a double dissociation. That is two groups: First, people for whom language is severely damaged and yet have normal cognitive abilities and, second, persons for whom normal cognitive abilities are grossly impaired and yet language remains intact. [17] [18] [19] Whilst extensive lesions in the left hemisphere perisylvian area can render persons unable to produce or perceive language (global aphasia), [20] there is no known acquired case where language is completely intact in the face of severe non-linguistic deterioration. [21] Thus, functional module status cannot be granted to language processing based on this evidence.
However, other evidence from developmental studies has been presented (most famously by Pinker [22] ) as supporting a language module, namely the purported dissociation between Specific Language Impairment (SLI), where language is disrupted whilst other mental abilities are not, [23] and Williams Syndrome (WS) where language is said to be spared despite severe mental deficits. [24] More recent and empirically robust work has shown that these claims may be inaccurate, thus, considerably weakening support for dissociation. For example, work reviewed by Brock [25] and Mervis and Beccera [26] demonstrated that language abilities in WS are no more than would be predicted by non-linguistic abilities. Further, there is considerable debate concerning whether SLI is actually a language disorder or whether its aetiology is due to a more general cognitive (e.g. phonological) problem. [23] [27] [28] [29] [30] Thus, the evidence needed to complete the picture for modularity – intact language coupled with gross intellectual deterioration – is not forthcoming. Consequently, developmental data offers little support for the notion that language processing occurs within a module.
Thus, the evidence from double dissociations does not support modularity, although lack of dissociation is not evidence against a module; this inference cannot be logically made.
Indeed, if language were a module it would be informationally encapsulated. Yet, there is evidence to suggest that this is not the case. For instance, in the McGurk effect, watching lips say one phoneme whilst another is played creates the percept of a blended phoneme. [31] [32] Further, Tanenhaus, Spivey-Knowlton, Eberhard and Sedivy (1995) demonstrated visual information mediating syntactic processing. In addition, the putative language module should process only that information relevant to language (i.e., be domain-specific). Yet evidence suggests that areas purported to subserve language also mediate motor control [33] and non-linguistic sound comprehension. [34] Although it is possible that separate processes could be occurring but below the resolution of current imaging techniques, when all this evidence is taken together the case for information encapsulation is weakened.
The alternative, as it is framed, is that language occurs within a more general cognitive system. [35] The counterargument is that there appears to be something ‘special’ [36] about human language. This is usually supported by evidence such as all attempts to teach animals human languages to any great success have failed (Hauser et al. 2003) and that language can be selectively damaged (a single dissociation) [37] suggesting proprietary computation may be required. Instead of postulating 'pure' modularity, theorists have opted for a weaker version, domain-specificity implemented in functionally specialised neural circuits and computation (e.g. Jackendoff and Pinker's words, we must investigate language "not as a monolith but as a combination of components, some special to language, others rooted in more general capacities"). [38]
In aphasia, a person may be unable to comprehend or unable to formulate language because of damage to specific brain regions. The major causes are stroke and head trauma; prevalence is hard to determine, but aphasia due to stroke is estimated to be 0.1–0.4% in the Global North. Aphasia can also be the result of brain tumors, epilepsy, autoimmune neurological diseases, brain infections, or neurodegenerative diseases.
Broca's area, or the Broca area, is a region in the frontal lobe of the dominant hemisphere, usually the left, of the brain with functions linked to speech production.
Psycholinguistics or psychology of language is the study of the interrelation between linguistic factors and psychological aspects. The discipline is mainly concerned with the mechanisms by which language is processed and represented in the mind and brain; that is, the psychological and neurobiological factors that enable humans to acquire, use, comprehend, and produce language.
Neurolinguistics is the study of neural mechanisms in the human brain that control the comprehension, production, and acquisition of language. As an interdisciplinary field, neurolinguistics draws methods and theories from fields such as neuroscience, linguistics, cognitive science, communication disorders and neuropsychology. Researchers are drawn to the field from a variety of backgrounds, bringing along a variety of experimental techniques as well as widely varying theoretical perspectives. Much work in neurolinguistics is informed by models in psycholinguistics and theoretical linguistics, and is focused on investigating how the brain can implement the processes that theoretical and psycholinguistics propose are necessary in producing and comprehending language. Neurolinguists study the physiological mechanisms by which the brain processes information related to language, and evaluate linguistic and psycholinguistic theories, using aphasiology, brain imaging, electrophysiology, and computer modeling.
Cognitive neuropsychology is a branch of cognitive psychology that aims to understand how the structure and function of the brain relates to specific psychological processes. Cognitive psychology is the science that looks at how mental processes are responsible for the cognitive abilities to store and produce new memories, produce language, recognize people and objects, as well as our ability to reason and problem solve. Cognitive neuropsychology places a particular emphasis on studying the cognitive effects of brain injury or neurological illness with a view to inferring models of normal cognitive functioning. Evidence is based on case studies of individual brain damaged patients who show deficits in brain areas and from patients who exhibit double dissociations. Double dissociations involve two patients and two tasks. One patient is impaired at one task but normal on the other, while the other patient is normal on the first task and impaired on the other. For example, patient A would be poor at reading printed words while still being normal at understanding spoken words, while the patient B would be normal at understanding written words and be poor at understanding spoken words. Scientists can interpret this information to explain how there is a single cognitive module for word comprehension. From studies like these, researchers infer that different areas of the brain are highly specialised. Cognitive neuropsychology can be distinguished from cognitive neuroscience, which is also interested in brain-damaged patients, but is particularly focused on uncovering the neural mechanisms underlying cognitive processes.
Elizabeth Ann Bates was a professor of cognitive science at the University of California, San Diego. She was an internationally renowned expert and leading researcher in child language acquisition, psycholinguistics, aphasia, and the neurological bases of language, and she authored 10 books and over 200 peer-reviewed articles and book chapters on these subjects. Bates was well known for her assertion that linguistic knowledge is distributed throughout the brain and is subserved by general cognitive and neurological processes.
Wernicke's area, also called Wernicke's speech area, is one of the two parts of the cerebral cortex that are linked to speech, the other being Broca's area. It is involved in the comprehension of written and spoken language, in contrast to Broca's area, which is primarily involved in the production of language. It is traditionally thought to reside in Brodmann area 22, which is located in the superior temporal gyrus in the dominant cerebral hemisphere, which is the left hemisphere in about 95% of right-handed individuals and 70% of left-handed individuals.
In psycholinguistics, language processing refers to the way humans use words to communicate ideas and feelings, and how such communications are processed and understood. Language processing is considered to be a uniquely human ability that is not produced with the same grammatical understanding or systematicity in even human's closest primate relatives.
Neurophilosophy or the philosophy of neuroscience is the interdisciplinary study of neuroscience and philosophy that explores the relevance of neuroscientific studies to the arguments traditionally categorized as philosophy of mind. The philosophy of neuroscience attempts to clarify neuroscientific methods and results using the conceptual rigor and methods of philosophy of science.
In neurology, semantic dementia (SD), also known as semantic variant primary progressive aphasia (svPPA), is a progressive neurodegenerative disorder characterized by loss of semantic memory in both the verbal and non-verbal domains. However, the most common presenting symptoms are in the verbal domain. Semantic dementia is a disorder of semantic memory that causes patients to lose the ability to match words or images to their meanings. However, it is fairly rare for patients with semantic dementia to develop category specific impairments, though there have been documented cases of it occurring. Typically, a more generalized semantic impairment results from dimmed semantic representations in the brain.
In neuropathy, primary progressive aphasia (PPA) is a type of neurological syndrome in which language capabilities slowly and progressively become impaired. As with other types of aphasia, the symptoms that accompany PPA depend on what parts of the brain's left hemisphere are significantly damaged. However, unlike most other aphasias, PPA results from continuous deterioration in brain tissue, which leads to early symptoms being far less detrimental than later symptoms.
In the field of psychology, nativism is the view that certain skills or abilities are "native" or hard-wired into the brain at birth. This is in contrast to the "blank slate" or tabula rasa view, which states that the brain has inborn capabilities for learning from the environment but does not contain content such as innate beliefs. This factor contributes to the ongoing nature versus nurture dispute, one borne from the current difficulty of reverse engineering the subconscious operations of the brain, especially the human brain.
In neuropsychology, dissociation involves identifying the neural substrate of a particular brain function through identification of case studies, neuroimaging, or neuropsychological testing.
Donald P. ShankweilerArchived 2006-06-26 at the Wayback Machine is an eminent psychologist and cognitive scientist who has done pioneering work on the representation and processing of language in the brain. He is a Professor Emeritus of Psychology at the University of Connecticut, a Senior Scientist at Haskins Laboratories in New Haven, Connecticut, and a member of the Board of Directors Archived 2021-01-26 at the Wayback Machine at Haskins. He is married to well-known American philosopher of biology, psychology, and language Ruth Millikan.
Laura-Ann Petitto is a cognitive neuroscientist and a developmental cognitive neuroscientist known for her research and scientific discoveries involving the language capacity of chimpanzees, the biological bases of language in humans, especially early language acquisition, early reading, and bilingualism, bilingual reading, and the bilingual brain. Significant scientific discoveries include the existence of linguistic babbling on the hands of deaf babies and the equivalent neural processing of signed and spoken languages in the human brain. She is recognized for her contributions to the creation of the new scientific discipline, called educational neuroscience. Petitto chaired a new undergraduate department at Dartmouth College, called "Educational Neuroscience and Human Development" (2002-2007), and was a Co-Principal Investigator in the National Science Foundation and Dartmouth's Science of Learning Center, called the "Center for Cognitive and Educational Neuroscience" (2004-2007). At Gallaudet University (2011–present), Petitto led a team in the creation of the first PhD in Educational Neuroscience program in the United States. Petitto is the Co-Principal Investigator as well as Science Director of the National Science Foundation and Gallaudet University’s Science of Learning Center, called the "Visual Language and Visual Learning Center (VL2)". Petitto is also founder and Scientific Director of the Brain and Language Laboratory for Neuroimaging (“BL2”) at Gallaudet University.
Brian Lewis Butterworth FBA is emeritus professor of cognitive neuropsychology in the Institute of Cognitive Neuroscience at University College London, England. His research has ranged from speech errors and pauses, short-term memory deficits, reading and the dyslexias both in alphabetic scripts and Chinese, and mathematics and dyscalculia. He has also pioneered educational neuroscience, notably in the study of learners with special educational needs.
In neuroscience, functional specialization is a theory which suggests that different areas in the brain are specialized for different functions.
Right hemisphere brain damage (RHD) is the result of injury to the right cerebral hemisphere. The right hemisphere of the brain coordinates tasks for functional communication, which include problem solving, memory, and reasoning. Deficits caused by right hemisphere brain damage vary depending on the location of the damage.
Carlo Semenza is an Italian neuropsychologist and cognitive neuroscientist. Carlo Semenza’s research activity mostly contributed to the field of aphasiology, neuropsychology of language, and numerical cognition.
Susan Curtiss is an American linguist. She is Professor Emerita at the University of California, Los Angeles. Curtiss's main fields of research are psycholinguistics and neurolinguistics. Her 1976 UCLA PhD dissertation centered on the study of the grammatical development of Genie, a famous feral child. Her subsequent work has been on grammatical development in children with SLI; maturational constraints on first-language development ; hemispheric specialization for language and language acquisition; and the cognitive modularity of grammar.
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