Pinker’s Concept of Genetic Double Dissociation

Pinker’s Concept of Genetic Double Dissociation
Introduction to Pinker’s Concept of Genetic Double Dissociation
In the field of neurology, double dissociation is a kind of neuropsychological impairment that involves the malfunctioning of one section of the brain independent of another part of the brain. For instance, if the brain's ability to recognize face gets impaired, but its ability to differentiate face expression, then this impairment is called double dissociation. This neurological impairment is a hereditary phenomenon that can occur in individuals and populations (Parsell, 2010). In psycholinguistics, Steven Pinker is a renowned figure who has extensively researched various linguistic impairment and their root causes. He is one of the proponents of modularity of the brain with specific reference to language modularity: a theoretical proposition that asserts that the human brain has a specific section or module associated with language acquisition. He states that the part of the brain linked with linguistic abilities is capsulated from the rest of the brain and holds a distinction regarding the ability to process information (Pinker, 2015). Thus, according to Pinker, language learning and speaking is a modular phenomenon isolated from other brain cognitive abilities.
Pinker provides several reasoning to substantiate his claim; for instance, he proposes that language and cognitive abilities are two distinct and isolated neurological processes, and the impairment of one entity does not affect the working of the other (1994). According to another scholar, this isolated neurological language module concept directly opposes other popular hypotheses. The Sapir-Wharf hypothesis is one such hypothesis that claims that language and cognition overlap each other, and language acquisition is responsible for shaping our cognition about the world and our perception of the world (Tommerdahl, 2005). However, despite admitting the development of inner speech via language, Pinker thinks this inner speech is nothing but a byproduct of language and has little to do with cognition. Nevertheless, to substantiate his claim further, Steven Pinker has used the examples of various linguistic disorders using several patients with solid language skills but weak cognitive abilities or weak linguistic abilities and stronger cognition.
Based on his study of various linguistic disorders, Pinker holds a strong proposition called the concept of double dissociation. He uses this concept to describe and explain the nature of the problem of people suffering from specific language impairment (SLI). Pinker attempts to verify the existence of brain modularity using SLI and William Syndrome (WS). In his proposition, he states that the malfunctioning of genes related to language acquisition impairs SLI patients' grammatical abilities; conversely, the malfunctioning of genes of cognitive skills impairs WS patients' cognitive abilities, but their language skills remain unharmed (Pinker, 2015). In other words, in patients suffering from WS, the cognitive module remains intact and functioning while the language module is impaired. Subsequently, this disease indicates the existence of a separate "social reasoning" module in the human brain; the ability of WS patients to learn music further reinforces Pinker’s claim of the role of brain modularity and double genetic dissociation (Parsell, 2010).
However, recent research studies have found contradictory evidence that negates Pinker’s genetic double dissociation theory. For instance, according to some modern research, language acquisition is also delayed in WS patients. Therefore, the following sections discuss the validity of Pinker’s theory by analyzing language and cognitive impairment in patients suffering from William Syndrome, SLI, and Broca’s and Wernicke's aphasia.
William Syndrome and Pinker’s Genetic Double Dissociation
William Syndrome is a congenital disorder characterized by certain characteristic features in individuals suffering from it. For instance, WS patients suffer from acute learning deficiency and other physiological problems; however, these patients show remarkable linguistic and social skills, especially since they strongly like music learning. This disease is caused by the deletion of genes 26 to 28 from chromosome seven at the time of fertilization (DerSarkissian, 2016). The proponents of brain modularity have used this disease to showcase the existence of a social, a language, and a music module in patients suffering from WS. Nevertheless, recent research studies have exposed several other aspects of this disease that mark the validity of the existence of brain modules. Based on modern research, WS patients suffer from impaired or atypical language development patterns; linguistic skills such as comprehension, repetition of the phrase, the average length of utterance, and object categorization show atypical patterns in these patients (Parsell, 2010).
Additionally, complex syntactical abilities, including the ability to understand and implement gender agreement, comprehend pragmatics and semantics of a speech, and process language phonologically, appear impaired in WS (Parsell, 2010). Based on research conducted by Stojanovik et al., the domains of language abilities, including syntactic skills, social-communicative abilities, and vocabularies that were supposed to remain intact in WS patients, do not appear intact. Therefore, the researchers argue that WS patients' profiles cannot be used to substantiate the existence of language modularity in the human brain. Based on their study of sample populations of SLI and WS patients, they found that no considerable difference is observable in terms of standard language acquisition impairment between the two groups of patients. Even more interesting was the observation that in some aspects of linguistic performance, the SLI patients outperformed the WS patients (Stojanovik et al., 2004). This empirical and research-based evidence strongly negates Pinker’s modularity model.
It is also evident that WS patients show remarkable sensitivity toward music; according to research, approximately 99% of WS patients have hyperacusis, characterized by hypersensitivity to all or some particular musical sounds (Parsell, 2010). Another research involved 118 WS patients in estimating their response to certain sounds. The result of the study revealed the existence of four different types of behaviors toward the sound in WS patients; additionally, hyperacusis was only 4.7%, but phobias (fear of specific sound) was approximately 90.6 % (Levitin et al., 2005). Moreover, WS patients also have an extraordinary ability to recognize faces and assess emotions from facial expressions. These individuals are also very capable of understanding facial signs that denote significant social expressions; during infancy, such people are reported to have a strange fascination for strange faces, and this trend continues throughout their life (Parsell, 2010). One research study used empirical data to verify that WS patients' fascination with faces is supplemented by a complex neural network of different pathways. Thus, despite similar behavioral responses, the cognitive response and neurological working are essentially different in WS patients (Mills et al., 2000).
Based on most modern research supported by empirical data, it has become apparent that both face recognition abilities and fascination for music in WS individuals are the outcomes of the cognitive resources remarkably different from a typical brain. Therefore, the WS patients' brains cannot be contrasted with the typical brain; consequently, WS patients cannot be presented as an example to support the hypothesis of double genetic dissociation (Parsell, 2010). Thus, WS patients do not use a neural network comprising functionally independent modules; instead, their cognitive abilities are based on a nuanced and intricate neural processing that cannot be supported by the concept of modularity of the human brain.
Specific Language Impairment and Pinker’s Genetic Double Dissociation
Specific Language Impairment (SLI) is a neurological disorder that impairs an individual's communication abilities; however, the person's hearing mechanism usually keeps working. Another sub-type of SLI involves a more significant impairment in the grammatical expertise of an individual; this sub-type is called Grammatical-SLI (G-SLI). The SLI patients suffer from acutely impaired comprehensibility of syntax, morphology, and phonology. This congenital disorder is linked with malfunctioning the left hemisphere and basal ganglia (Van der Lely & Pinker, 2014). Globally, this abnormality occurs in an average of 7% of children of a population segment. Children suffering from SLI experience acute difficulties identifying, understanding, and creating simple and complex syntactic structures, including wh-questions, passive sentences, tenses, and word inflection. According to the latest research to determine the neurological distinction between Grammatical SLI and SLI based on the use of electroencephalography (EEG), magnetoencephalography (MEG), functional MRI (fMRI), and diffusion ...