User:Ktharrelson/sandbox

=Cognitive Advantages to Bilingualism=

The effects of multiple language acquisition on cognitive performance have been researched using both behavioral and imaging techniques. Behavioral measurements include the Stroop Task, the Simon Task, and others. These tasks measure attention performance and control of response inhibition. A cluster of recent studies examines the speed of responses between mono- and bilinguals in these tasks. Brain imaging techniques have also been used to assess cognitive processing differences between monolinguals and bilinguals. Typically fMRI studies are used, although the slightly more invasive PET and EEG techniques have also been employed. Performance on standardized verbal tests have generated an additional source of data for this type of research.[1] A major challenge in assessing the effects of multiple language acquisition on cognitive performance has been the assembly of rigorously matched groups that differ only in language acquisition, and the use of tests in which language itself is not a testing variable that requires additional controls. The results from these types of experiments have confirmed some commonly-held beliefs about cognitive performance and bilingualism, while providing some surprising new insights into this relationship.

Executive Control
Executive control is a cortical function that determines and focuses attention. Bialystok has found that “bilingual children gain control of executive control functions earlier than monolinguals, bilingual adults have more executive resources available when executive demands become especially complex, and bilingual older adults show a less steep decline in the slowing down of these functions with age.”[2] In other words, executive functions develops “earlier in childhood and declines later in older adulthood.”[2] Enhanced control of executive functions in bilinguals develops from the use and practice of speaking two separate languages. “Thus, the networks responsible for conflict resolution, inhibition, and flexibility are strengthened over time and fortified for all uses."[3] Even though using two languages seems to be a major factor in the development of better executive control, there seems to be an advantage in executive control already in bilingual 7-month-old infants, as shown in a study done by Kovacs and Mehler. Further research is needed to determine how bilingualism can confer advantages in cognitive processing even before either of the two languages have been learned.

During the first 4-5 years of age, children develop rapidly and achieve better voluntary control of their behavior. Effects are most apparent in situations in which behavioral output is contingent upon proper sequential ordering of otherwise conflicting information (e.g. do x only after y). Bilingualism enhances “children’s control over attention in conflict situations” so “bilingual children should master these executive control tasks more efficiently or more precociously than comparable monolingual children."[3]

Because the processes involved in executive function, including selective attention and inhibition, are practiced so much more in bilinguals than monolinguals, they have a more robust system that allows more focus on relevant cues, as opposed to distractions, across a variety of functions, which leads to a bilingual advantage in executive control.

The Stroop Effect
Bilinguals tend to perform better on tasks like the Stroop effect, which is a task that measures the time required to identify a color by written word when there is a corresponding distractor cue (e.g. identification of the word 'red' when written in blue, versus the word 'blue' written in red). People tend to be comparatively slow to give the correct identification because attention also goes to the actual color of the word. “Similarly, in a task in which children were trained to judge whether the grammatical form of a sentence was correct and to ignore the meaning, bilingual children were more able than monolinguals to report that sentences like ‘Apples grow on noses’ are said the right way, even if they are silly.” Because bilinguals are better at overcoming and ignoring distracting cues, they have a processing advantage and higher executive control.[3]

Kovacs and Mehler
Kovacs and Mehler did a study using 7-month-old infants either raised in a monolingual, Italian-language environment or in a bilingual household. The task they used to test the babies’ executive control was similar to the A-not-B task, which was a task first used by Jean Piaget in testing his theory of cognition. The task involves an experimenter repeatedly concealing a toy in the “A” box, which the child consecutively finds but when the experimenter shows the child he is moving the toy under box “B”, the younger infant (typically under 10 months) will still look under box “A”.

In Kovacs and Mehler’s case, they used a computer screen to direct the infant’s gaze to a certain side of the screen in order to receive a visual reward and when the side of the screen switched, monolingual babies made more perseverative errors, or continued to look towards the previously-rewarded side of the screen even though it was no longer rewarding, while children in the bilingual homes would redirect their gaze effectively. "The bilingual babies learned to redirect their gaze to the opposite side of a screen to receive a visual reward while the monolingual babies didn't learn to shift their gaze."

“Thus, even this primitive origin of executive control may be influenced by a bilingual environment long before children become verbal."[3]

The Simon Task
The Simon task, in which participants are instructed to press the right key if a green square appears and the left key if a red square appears, was used by Bialystok to compare mono- versus bilingual cognitive skill. When a green square appears on the right and the red square appears on the left side of the screen, the correct key and colored square correspond and so it is a congruent trial. When it is the opposite, they conflict and it is an incongruent trial. A control group experienced all the squares in the center of the screen just to measure normal reaction times. Bialystok was measuring the RT (reaction time) between monolinguals and bilinguals in the incongruent trials to demonstrate the differences in increased RT because of the need for resolution of the conflict in the trials.

The reaction time was significantly lower for bilinguals than monolinguals at all ages (30-80 years of age). “These data illustrate the influence of bilingualism on improving control over competing cues, in this case, the position of the stimulus and the position of the correct response key, and the persistence and enhancement of this effect across the lifespan."[3]

Bilingual language processing
A few contesting theories strive to explain the lexical organization in bilingual individuals. Separate-store models claim that there are separate lexicons for each language, which are connected at the semantic level. Contrastedly, the common store models make the claim that there is only one collective lexicon and one semantic memory system at work in bilinguals, and that words from both languages are stored in this system and connected directly together. Most current evidence, according to Harley, supports the latter hypothesis, but a third additional possibility also crops up: that some individuals (if not all) utilize a mixture of both common and separate storage mechanisms. Certain studies have determined that cognates (words in different languages with the same root, meaning and appearance), concrete words and culturally similar words act as though they are stored in a common space, whereas abstract words appear to be situated in separate stores.

Aging in Adults
Age of second-language acquisition seems to play a deterministic role regarding the mental representation and access to words, with late learners seemingly tending to have separate lexicons mediated at the conceptual level (whereas early the body of early learners is more often meshed in a similar space). Also, later acquisition is paired with a reduction in productive language abilities: searching for words or names becomes more time-consuming and salient, and thus lexical access becomes problematic. These issues with language comprehension and production are to some degree a product of normal aging, and are therefore present in monolinguals as well, but are simply more pronounced in bilinguals’ expression of the secondary language.

The above-mentioned controversy is especially significant because a major topic of interest is how bilinguals prevent languages from interfering with one another. It has been suggested that, during conversation in a particular language, speakers use low-level information to block out words in the non-target language, so that the meanings of the words in the other language cannot become activated (therefore, the semantics of the non-target words are activated sparingly, since it appears that semantic activation is not the most economic utilization of energy).

Also, "lifelong bilinguals, however, appear to be protected from the decline in executive control in that, although inevitable, the decline is delayed and perhaps modulated by this experience."[3] As well as delaying the decline in executive control, bilingualism can delay onset of dementia, especially Alzheimer's, for up to four years. According to Bialystok, "This is an enormous difference and suggests that bilingualism, like other stimulating mental activities, allows the brain to continue to function in spite of growing pathology."[3]

Brain Structure
In terms of brain structure, it has been suggested that, because the right brain hemisphere is involved in secondary language acquisition, language is not as asymmetrically represented in bilinguals as it is in monolinguals (in monolinguals, language information is confined mostly to the left hemisphere). In fact, bilinguals with damage to the right hemisphere tend ot show significantly more aphasia than do monolinguals.

The lack of asymmetry in bilingual language representation in the brain is especially prominent in late learners. While lexical information of both early and late learners tends to be organized similarly in the brain, imaging studies have suggested that a later time of acquisition does create a variation in how grammatical aspects of the second language are organized (that is, a later acquisition time places secondary language grammar separately from primary language grammar information).

Overall, however, second-language acquisition always involves a restructuring of a learner’s language knowledge bank, and follows a U-shaped curve: initially, learning is efficient and rapid, with a decline in performance in the middle stages, before becoming skilled in the second language.

Conclusions
Early research suggested that learning two languages in childhood was detrimental to a child's cognitive abilities.[6] This was explained by the idea that the two languages were learned independently and the knowledge of learning one did not transfer into the other. It was thought that as more was learned in one language, less could be learned in the other. This gives the idea of there being a total amount of language acquisition, and so the pieces learned in each language together have to add up to this total. For this reason parents and teachers tried to force children to only learn one language instead of cultivating the ability to learn both. The consensus among linguists, as well as the general public today, however, is leaning towards the opposite; the idea that knowledge in the two languages would be kept separate instead of influencing each other is rejected as irrational by many. For example, a child who has learned the concept of adding and subtracting in one language would not need to re-learn the concept in another language. By that same token, a child who has learned to recognize that spoken language can be broken up into words, which can be represented in writing in one language is not going to need to be re-taught the idea of writing representing spoken language.

The evidence generated by administration of the Stroop and Simon tasks clearly indicates an enhanced ability in bilinguals to focus their attention and ignore distractive inputs. These data demonstrate this advantage of multiple language acquisition from a young age but it is still unknown whether these advantages can be attained by acquiring a new language later in life.