User:Jen821/Cognitive effects of multilingualism

Objective for editing this article:

 * over-reliance on primary sources -- need to give more impartial pieces of evidence
 * too much detail when it comes to explaining studies -- need to simplify so that it's easier to understand
 * not enough sources are attributed -- need to add more citations
 * poor organization -- need to make the overall article easy to follow
 * grammar/sentence structure -- need to clean up ungrammatical sentences

Executive function
David -  The primary problems with these sections, as reflected in the talk tab, is that they focus too much on primary sources and go into too much technical detail about individual studies. There are also several awkwardly worded or ungrammatical sentences.

Evidence of advantage (was "Clarification: possible connection")
David

Explanations of advantage (was "Analyses")
David

Opposing views (was "Bilingualism vs. executive control" and "Clarification: In opposition")
Hannah

History
Jen -- I have gone through and added more citations to this sections as well as cut down the details when explaining studies. I also added a paragraph that addresses current studies and the future of research regarding the cognitive effects of multilingualism. There were also some grammatical changes that I made to this section. Additionally, I took out the first part of the section, as it seemed irrelevant to the rest of the history discussed.

Non-native bilingualism
Jen -- This section, while very interesting, just brings a lot more to the article and overwhelms the content already present, so the best option is to just delete it.

Executive function
Executive function is the set of abilities that facilitate the completion of goal-oriented tasks and is thought to involve cognitive processes such as attentional control, cognitive inhibition, inhibitory control, working memory, and cognitive flexibility. In many studies, bilinguals have outperformed monolinguals in tasks that measure various aspects of executive function, particularly those which require some form of selective attention. Based on findings that both languages are simultaneously active in the bilingual brain, it has been proposed that the attentional demands on executive function in selecting between languages may account for the positive correlation between bilingualism and performance on executive function tasks. However, in recent years, many studies have failed to find a positive correlation between bilingualism and performance on executive function tasks and a number of meta-analyses have found the evidence across studies inconclusive.

Evidence of advantage
In many studies, bilingual children have been shown to outperform monolinguals on tasks that measure various aspects of executive function including stroop tasks, flanker tasks and dimensional change card sorting tasks. Many of these tasks require selective attention while ignoring distracting cues or a prior response.

In dimensional change card sorting tasks, bilingual and monolingual children are asked to sort cards first by one dimension such as symbol shape and then by another such as color. In several studies, bilingual children have been shown to be significantly better able to ignore the prior sorting method after switching to a new sorting method.

While the ability to perform dimensional change card sorting tasks can be measured at around 3 to 5 years old, other studies based on eye movement show similar advantages in attention and ignoring invalid cues may emerge as early as 7 months. Some studies have shown continued, though lessened, advantages for lapsed bilinguals. While studies have shown similar positive correlations on executive function tasks in older adult bilinguals, the results for young adults have been inconsistent.

Explanations of advantage
A frequent explanation for bilinguals' apparent advantage in executive function tasks was that a constant need to suppress one language while using another led to improved inhibitory control in executive function. This was thought to account for bilinguals' apparent ability to ignore distracting cues and prior response methods and coincided with David Green's "inhibitory control model" of bilingual language processing which was proposed in 1998. This explanation was bolstered by a study of unimodal bilinguals (bilinguals who communicated with two spoken languages) and bimodal bilinguals (bilinguals who used one spoken language and sign language) which found that only unimodal bilinguals performed better on flanker tasks. Because bimodal bilinguals can express themselves in both languages at the same time, it was thought that they may require less inhibition.

Other components of executive function which have been proposed to be affected by bilingualism include task shifting, monitoring and various components of attention.

Ellen Bialystok, who initially endorsed the explanation of enhanced inhibitory control, has since concluded that it does not fit the data. She cites the presence of attentional effects in infant bilinguals along with meta-analyses showing that in studies where bilinguals demonstrate an executive advantage, they typically outperform monolinguals in tasks both with and without distracting cues. Inhibitory control would only predict improved performance with distracting cues. She proposes that bilingualism may alter selective attention more broadly.

Opposing views
The idea that bilingualism enhances executive function is not universally accepted among linguists. Mixed experimental results and the possibility of confounding variables have led some researchers to question the existence of a positive association.

Hakuta and Diaz addressed the chicken and egg question concerning bilinguals and their reported enhanced cognitive abilities: do children with greater cognitive abilities tend to learn more than one language, or could knowing more than one language contribute to enhanced cognitive ability? The results of their study showed a higher correlation with the degree of bilingualism (how proficient the individuals were in each of their languages) of their sample and scores on the test, indicating that bilingualism did in fact predict performance (and therefore cognitive ability). It is important to note that most native bilinguals learn a second language because of their environment; not necessarily because they are more intelligent. In most cases, they have grown up in a family where use of the two languages is necessary: the child's innate intelligence is not a significant factor in acquiring two languages.

Ramesh Kumar Mishra presents evidence from various linguists that suggests other external factors which may have a role in the reported correlation between bilingualism and executive function. One linguist, Virginia Valian, suggests that one such factor is inconsistent methodology. Valian notes that executive function is not uniformly defined and it is not known which tasks can most effectively measure it. She also notes that bilinguals are not consistently better at all executive function tasks. Finally, Valian points to a host of socioeconomic and environmental aspects of bilingualism that could influence executive function. Mishra builds upon Valian's suggestions by arguing that research studies should shift to comparing bilinguals of different proficiencies instead of bilinguals to monolinguals, or comparisons of bilinguals to monolinguals with non-linguistic skills that are positively associated with executive function.

Claims of publication bias dispute the validity of findings supporting bilingualism and cognitive benefits of executive control. For example, a study examining abstracts of research on bilingualism and executive control between 1999 and 2012 found the research results in support of an advantage were published more often and results that did not support the theory were published least often. Lack of difference in sample size, measure, and statistical power across these studies suggests not error but publication bias.

Another meta-analysis by Lehtonen et al. presents further skepticism for the correlation between bilingualism and executive function. In an analysis of 152 studies, they found a small advantage of executive function in bilingual adults. However, after correcting for non-linguistic factors such as the external variables discussed by Mishra, and the publication bias discussed by de Bruin et al., they found no significant advantage of bilinguals over monolinguals.

History[edit]
Over the course of the past few years, the prevalence of bilinguals in the United States has increased dramatically. While the United States Census Bureau does not directly poll for bilingualism, they do poll for what languages are used in an individual's home, and if it is a language other than English, they then poll for how well that same individual speaks English. In 2012, François Grosjean, a professor of Linguistics from the University of Neuchâtel, interpreted the results from the Census Bureau as follows: 11% of the population was bilingual in 1980, 14% in 1990, and 20% in 2012. This positive increase raised a question into the depth of cognitive activity in bilinguals and whether or not there were benefits in multilingualism to be found.

The majority of research on the cognitive effects of bilingualism has been conducted since the early 1960s. According to the Singapore Management University (SMU) School of Social Sciences, research before the 1960s on bilingual individuals was varied, but commonly supported the idea that there were disadvantages to bilingualism. The general opinion was that bilinguals would have smaller vocabularies and stunted cognitive abilities, and children learning two languages from a young age would be spending too much of their energy differentiating and building the two languages to become competent in either one. This perspective was consistent with the idea that being bilingual was detrimental to a child's linguistic and cognitive development. According to a journal called "The Journal of Genetic Psychology," various reported studies at the time held a similar view on bilingualism, and it was referred to as a "problem of bilingualism" or the "handicapping influence of bilingualism." Following studies reported that bilinguals performed worse in IQ tests and suffered in most aspects of language development. Journalist Rafael M. Diaz from Yale University mentions that perspectives like these were in part believed to have been influenced by variables that had impacted or changed how a society functioned.

In 1962, Elizabeth Peal and Wallace Lambert published a study highlighting the importance of controlling for such factors as age, sex, and socioeconomic status (SES) as well as of having a standardized measure for bilingualism when selecting a sample of bilinguals to be studied. In their study, they carefully matched bilingual to monolingual participants, and found that the bilinguals appeared to have significant advantages over their monolingual peers and outperformed them in both verbal and non-verbal tests, especially in the non-verbal tests. After this study, and other similar studies, the literature began to undergo a shift of focus erring more particularly towards areas of cognitive development and aptitude such as perception and executive functioning.

In 1977, the AIR (American Institute for Research) published an influential study that discussed bilingualism as it relates to education and the effects on a child's performance in class. This study, along with other research of its time, played a large role in society's understanding of multilingualism and the effect it has on the brain. While historically relevant and necessary, in the context of meeting modern methodological standards, these studies in particular are argued to be missing necessary pieces of data that create controversy over their credibility. With current research and data suggesting benefits to bilingualism, the soundness of the former studies' conclusions are in brought into question. According to "The Journal of Genetic Psychology," many of these studies employed unstandardized and subjective definitions of bilingualism (e.g., labeling someone as bilingual or monolingual through assumptions based on the national origin of that person's parents or even based on that person's family name), raising the concern that there is no way of determining whether their samples were truly representative of a bilingual population. Another element that contrasted with more modern researching techniques was the lack of a control for socioeconomic status (SES) -- verbal-intelligence tests were often administered to non-proficient speakers of a second language in that second language.

More recent studies have acknowledged the advantages of multilingualism with regards to cognition and executive function more than in the past. Starting from the 1980s, researchers claimed that metalinguistic awareness as well as cognition is improved due to multilingualism. Studies in the early 21st century also claim that the number of languages an individual speaks is a significant predictor of their cognitive state. However, the increase in research regarding the multilingual advantage has now led to a debate about its extent. A 2021 paper by Kristina Backer and Heather Bortfeld analyzes the discussion around the cognitive effects of bilingualism and unpacks the various factors that play into this claimed advantage. The controversy that arises is whether language advantages due to multilingualism -- such as dealing with cross-language competition -- can actually be transferred to domain-general tasks. Those advocating for these benefits claim that they vary between individuals based on factors such as the variability of the sociocultural contexts of the languages, the speaker's age, the specific tasks implemented in the studies, and the different analytical tools to evaluate the results of the studies. However, opponents to these advantages claim that language-specific advantages to multilingualism do not get directly translated to domain-general tasks. Overall, current research today has shown us that much work needs to be done with regards to the numerous factors that play into the bilingual advantage. As seen with reports like Backer and Bortfeld's, the research community plans to direct their future studies towards more intensive analyses regarding the cognitive effects of multilingualism.

Non-native bilingualism[edit]
Nonetheless, Ghil'ad Zuckermann explores the effects of non-native multilingualism, including, for example, "better cognitive performance in old age (Bak et al. 2014), a significantly later onset of dementia (Alladi et al. 2013), and a better cognitive outcome after stroke (Alladi et al. 2016; Paplikar et al. 2018)."