Sample Essay:

Language Localisation

Language has been defined as a “system of symbol and rules that enable us to communicate” (Harley 2001). In fact the same author believed that what separates human from animals is the existence of our systematic language. While it is true that animals have their own way of communicating, the complexity of human language makes it capable to convey any message. Language is used to express identity, express emotion, interact with others, control the environment, think with, record facts, play with it, and use of its sounds (Crystal 1998). It is not astonishing to find out that various scholars have studied the correlation between language, human behavior and human anatomy. One of the premises advanced by different scholars is that language is localized in two specific areas of the left hemisphere of the brain. This theory challenged the early theory of language lateralization. This paper posits that _____.

Human brain is an essential organ of the body which is composed of two hemispheres – left and right (Kolb and Whishaw 1996). According to Harley (2001), each hemisphere specializes a respective task in the human body. The two hemispheres of the brain have contralateral relationship with the human body parts (Field 2003). Generally, if the individual is right-handed, his brain’s left hemisphere primarily functions with time-based and analytic processing; whereas the right hemisphere of the brain functions with spatial and holistic based processing. The implication of such specialization of function is that an estimate of 96% right-handed individuals’ language function at the left hemisphere of the brain (Ibid). This only supports the theory advanced by Martensson (2007), that lateralization also affects the handedness of a person.

The lateralization theory is the “view that one of the hemispheres of the brain has or develops a special responsibility for language” (Field 2004). Among the earliest proponents of this theory were Marc Dax (1836), Paul Broca (1861), and Carl Wernicker (1874).  They believed that that the left hemisphere was the dominant one for language in most people. Scholars have cited several pieces of evidence to prove this theory.

The first evidence is an incident of brain damage caused by invasive surgery, accident, or stroke, wherein an impairment of the left hemisphere would affect the language of the victim (47). A common example of this is aphasia – a condition where an individual suffers difficulties in speech and sensorymotor control over the right part of his body (Martensson 2007). This is true regardless of the gender of the individual; hence, male and female suffer the same language impairment (Harley 63).

Another evidence that led to this conclusion is a pre-surgery practice of injecting sodium amytol (Wada injection) to deactivate one hemisphere of the brain to find out which side dominates for the language. The result shows that it is usually the left side of the brain (47). Commisurotomy is another method that prove this theory. This is an operation whereby the corpus callosum is severed in order to alleviate epilepsy. It has been surmised that those who underwent this kind of operation are able to name objects through the right field of vision, which is connected with the brain’s left hemisphere. Dichotic listening is another method to test this theory. When random messages are presented to both ears, the right one which directly links to the brain’s left hemisphere would likely override the left ear. The implication of such means that the right ear dominates the speech function while the left ear tends to dominate intonation, music, and rhythm (47).

To prove this whether accurate or not, an experimental task using a dichotic listening test was conducted to 20 subjects in order to discover their dominant hemisphere. The researcher recorded ten monosyllabic words on one tape, with no pauses between them, and then ten different monosyllabic words on a second tape. To test which hemisphere is more dominant, one earpiece was attached from the headphones to the first tape and one to the second. The subjects were then asked to insert one earpiece into their left ear and listen to the following words: ANT; EYE; DREAM; LAUGH; RAIN; PEACE; SMILE; ROSE; ROCK; SEA. Afterwards the second tape was put in their right ear which played the following words: LIFE; LOVE; WORLD; HEART; WOLF; KING; FISH; ICE; ART; TIME. The recordings were played simultaneously. Immediately after listening, the researcher asked the subjects to write down as many words as they can recall from the recording. The table below shows the summary of the experiment.

Table 1. Summary of the Dichotic listening test

Preference for words in the right ear indicates left hemisphere dominance and vice versa (as advanced by the theorists of cross lateralisation). The result of the experiment showed that majority of the subjects recalled the words played in the right ear. Out of 20 subjects, 13 recalled more words in the right ear than in left one. Hence, is not astonishing to find out that more subjects have dominating left hemisphere and mostly right-handed. However, this is not always the case. It is important to note that not all subjects in the experiment who recalled more words in the right ear have dominating left hemisphere and vice versa. For instance, subject numbers 2, 4, 10, and 11 recalled more word/s in the right ear yet the left barely dominates the right. This is also the case of subject 14 who recalled more words in the left ear but his right hemisphere barely dominates the left. The experiment in fact created a middle ground where there exists no absolute dominating hemisphere of the brain. This experiment apparently suggests that the right hemisphere still plays a significant role in the language process of an individual.

Interestingly, the result of the experiment of subjects 4, 5, 14, and 19 also proved that not all individuals whose left hemisphere dominates the right are right handed and vice versa. Rasmussen and Milner (1977) earlier argued that an estimate 70% of left handed individuals have dominating left hemisphere. While this theory finds application to the conducted experiment, a smaller percentage (as opposed to 70%) reflects the result. Half of the subjects whose dominant hemisphere is left are also right-handed.

This view is associated with the proponents of language localization, which supports the idea that language is widely distributed in the brain.  One of the methods used to prove this theory is the brain imaging technique. Recent result of researches using this method suggested that: 1.) language is widely distributed throughout the human brain; 2.) language is hierarchically organized; 3.) language undergoes distinct processes in accordance with the signal’s physical form; 4.) Syntax and semantics are intertwined; 5.) Activities like mnemonic tasks activate various portions of the brain responsible for word meaning; 6.) Grammar is also distributed throughout the human brain (Field 2004).

Field (2003) is one of the scholars who proposes the localization theory. He posits that the left hemisphere of the human brain is associated with symbolization and analytic processing. Thus, it is generally implicated in the processing of language. On the other hand, the right hemisphere is in charge of spatial and perceptual representation. It is important to note that despite this generalization, it is not accurate to conclude that the right hemisphere does not contribute to the language processing. There are vast network that connects the two hemispheres in order to ensure the harmonization of operation (Field 2003). This idea was supported by Harley when he argued that while language localization happens in the left hemisphere of most people, it is wrong to assume that it is already restricted in such area. This is because there are some language functions that does not take place in the left hemisphere. For example, the right hemisphere has an essential role in the development of the acquired disorder deep dyslexia (Harvey 2001). This only supports that there are multiple connections in the brain involved in language comprehension and production. While there are some parts of the brain that play more important function than the other portions, specific processes cannot be localized in a specific part of the brain.

There are further two areas in the left hemisphere of the brain regarded as speech centra – Wernicke and Broca (Martensson 2007). Recent researches led to conclusion that an impairment at the Broca’s area directly results to an individual’s loss of function and grammar words as well as language production impairment (Ibid). However, it should be noted that such speech impairment does not affect the individual’s understanding of speech rather his production of speech usually becomes slow and telegraphic (Ibid). This means that such individual finds it difficult to interpret semantically sentences.

On the other hand, individuals whose Wernicke area has been damaged tend to utilize function words and speak fluently. These individuals usually concern lexical and syntax words; thus, they find it difficult to produce comprehensive sentences and understand language. Further, there are several cases where damage of Wernicke results to anomia or condition where an individual loses the capability to name things (Ibid).

Reference

Crystal, D. (1998). Language play. Harmondsworth, UK: Penguin Books.

Field, J. (2003). Psycholinguistics. Routledge.

Harley, T. (2001). The Psychology of Language From Data to Theory. Psychology Press Ltd.

Kolb, B. and Whishaw, I. (1996). Fundamentals of Human Neuropsychology. New York, N.Y Worth Publishers.

Martensson, F. (2007). Neurolinguistics.