Ageing and Its Effect on Language

The dramatic increase during the 20th century in the number of people reaching old age has helped to continue a long tradition of research into the effects of ageing on human cognition. In the past the plurality of humans departed, by current standards, early in life with sound mind. While the modern individual is no longer troubled with small pox or polio, he is however, in a race between death and mental deterioration. To live is to be doomed to an unalterable fate of mental antiquity, checking out a decrepit, feeble-minded, old man. Until somewhat recently, this was the imagery tied to the ageing process in the mind of laymen and scientists alike. They believed with the onset of older age, i.e. after the developmental peak of say 40, there was a slow decline of all mental functioning. However, recent research indicates, through the use of functional magnetic resonance imaging (fMRI), "some types of language processing may be performed more efficiently in older individuals" (Crown).

Theorists of the mid-Twentieth century were not incorrect in concluding that the human mind experiences mental decline as a function of age, they simply failed to realize the accommodating nature of the brain. Despite the decrease in brain activity that naturally occurs in aging, "the brain...not a static organ...may accomplish the same task in different ways as a function of a person's age," according to Darren Gitelman, an associate professor of neurology at The Feinberg School of Medicine at Northwestern University. In other words, although a person may experience decline in the temporal lobe, for example, the brain finds alternate ways in which to execute a function that might have lapsed as a result of the loss. Our focus however, is more specific to the frontal lobe and the effects of age on language.

How age affects human ability to communicate is perhaps the most important area of Gerontology. After all, language is not only an integral part of humanity; it also serves as the bridge that binds human beings to this world and to each other. Without language, existence would simply be a series of sensory experiences, void of any framework to categorize and prioritize this existence. To be certain, the framework of language creates, as academic Martin Heidegger says, "an ontologically determined finite set of possibilities which man can use for its own specific existence" (Polt). Without sounding too much the philosopher, existence without the capacity to utilize language, is not that which we term "human existence." It is because of a fervent belief that language is the lifeblood of human experience that this paper reserves itself for the investigation of the notion that some functions of the human brain as it relates to language remain operational and that others decline.

We should first note that language is part of a larger system known as semantic memory. "Semantic memory concerns learning and remembering the meaning of words and concepts that are not tied to specific occurrences of events in time" (Cavanaugh). It is our vast store of knowledge and skills, including orthographic and phonological information associated with our language. Research has established that semantic memory is relatively unimpaired with ageing whether tested by explicit or implicit means. (Cavanaugh) For example, direct tests of vocabulary "consistently show age constancy throughout adulthood, as does knowledge tested implicitly via priming techniques" (Salthouse). A similar pattern emerges from word association tests, a tool which measures the organization and availability of semantic information. "Word association responses [for young and older adults] matched for verbal IQ and educational level do not differ in relative response frequency, in number of unique responses, or in overlap of responses within their age groups" (Howard). This shows that older adults not only retain their ability to remember words, but also can relate them to one another sensibly. We can further conclude that if the subjects are able to link words together, they also link the ideas they associate with each word. Essentially, this is basis for human language and consciousness: assigning objects words, and linking them through ideas. The findings from studies of memory and ageing suggest there is constancy on tests of familiar or pre-existing information.

However, pre-existing verbal information is not spared entirely. The degree to which it is spared in older adults depends on whether the information "is accessed on the input side, i.e., language comprehension, or on the output side, i.e., language production" (Madden). The input side of language involves "perception of the letters and speech sounds that make up words, and comprehension of the meaning of words and sentences" (Madden). These input side processes remain remarkably stable in old age, independent of sensory deficits and declines in the ability to encode new information. (Madden) The semantic priming paradigm is a technique used by psychologists to measure the processing of word meanings and their organization in the brain's memory. Despite age, there is a reduction in the amount of time a subject takes in order to identify target words when they follow a semantically related word as opposed to a semantically unrelated word. This is known as the semantic priming effect. (Madden) An example might be to locate the word "apple" when it follows either "fruit" or "television". In both instances of young and old age, a subject would identify "apple" more quickly when it follows "fruit" as opposed to "television". "The fact that semantic priming effects are at least as large in older as young adults is evidence for the integrity of this important language comprehension process in old age" (Burke and Harrold).

Age constancy is also found for the processes involved in comprehending words in sentences. Dr.'s D. Burke and R. M. Harrold cite a classic example in a 1988 article from Language, Memory, and Aging,

"...when young and older adults read sentences that bias a specific property of a noun, e.g., oranges in The oranges rolled off the uneven table, they are faster to verify the property of oranges relevant to the sentence, e.g., Oranges-Round?, than to verify a property irrelevant to the sentence, e.g., Oranges-Juicy?. However, property-noun verification was faster for Oranges-Juicy? than for Oranges-Round? after reading The oranges quenched the thirst of the hot children..."

These findings suggest that both young and older adults associate relevant meanings between the target noun and the context of the sentence in which it is fixed