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Early studies suggested that bilingualism was a disadvantage in terms of people’s mental abilities. Have recent studies supported that idea?


The present paper pragmatically discusses research and scholarship investigating the impact of bilingualism on language and cognitive abilities.  It looks at the intricacies surrounding the ways in which research has conceptualised bilingualism in relation to language and cognitive ability.  In this way, it firstly examines bilingualism and how this concept has been theorised within relevant body of literature.  Secondly, it takes critical overview of previous studies connecting bilingualism to cognitive deficits.  Thirdly, this paper investigates the effects of bilingualism on language and cognitive ability in the light of current findings.  The present paper takes the position that despite early studies suggesting that bilingualism was detrimental to cognition, subsequent research corroborated precisely the opposite.  

Bilingualism and being bilingual

It could be argued that the idea of an ‘uncontaminated’ monolingual is perhaps no more than fiction, given that exposure to fragments of other languages is somewhat unavoidable (Marian & Shook, 2012).  In this respect, it has been postulated that in the present social context languages are often not immune to intrusion of phrases and words that are somewhat ‘universally’ appealing (Duncan & De Avila, 1979).  To put simply, bilingualism is often defined as the ability to use two languages (Grosjean, 1989).  However, much debate surrounds the definition of bilingualism.  This is mainly due to the fact that individuals vary in their bilingual characteristics, from minimal to advanced proficiency in bilingual skills (Marian & Shook, 2012).  Furthermore, a person may describe him/herself as a bilingual when in fact he/she can only communicate orally.  In actual fact, when one thinks of a bilingual individual the general assumption is that of a person that can, in one way or another, understand and speak two distinct languages.  However, it could be argued that some individuals who have knowledge of a second language do not necessarily fit that description.  For instance, some individuals can be quite proficient at reading when it comes to second language knowledge, but lack the ability to speak it.  Furthermore, one would like to think of bilingualism as a categorical variable, but it might be in fact a continuous one, given the wide range of language skills among different people (Bialystok, 2001).  In this way, one must conceptualise bilingualism in terms of both type of language proficiency, as well as the degree of language proficiency in two languages that each individual might posses.

The Effects of Bilingualism on Cognitive Abilities

However, what if any, are the effects of language in human cognition?  In this respect, the early twentieth century was marked by the predominant assumption that bilingualism could potentially confuse individuals and lead other cognitive deficits (see Arsenian, 1937; Darcy, 1963; Jensen, 1962; Macnamara, 1966; Diaz, 1983; Cummins, 1984; Hakuta & Diaz, 1985).  Other studies have also found that there are intrinsic differences in colour perception between bilingual and monolingual groups (Özgen, 2004).   However, one could argue that there were some major flaws with early studies devoted to this area of research.  For instance, the well known study conducted by Hakuta & Diaz (1985) did not control for differences relating social and economic background when comparing children who were either monolingual or bilingual.  In this respect, it could be argued that children who were fluent in just one language were typically higher at the socio-economic level compared to their immigrant children counterparts, and this factor has put bilingual children at a remarkable disadvantage.  Another important aspect which was neglected by Hakuta & Diaz (1985) was measuring the level of proficiency.  In this respect, they have failed to measure and control levels of language proficiency in bilingual children involved in their study.  The connotation of bilingual was simply based on where their parents were born, where the children lived at the time of the study, or whether or not their parents were foreign born.  Thus, one must conclude that due to lack of control for language proficiency in bilingual children, previous studies investigating the impact of speaking two languages have often included individuals with relatively limited competence or exposure to any given second language.  In this way, it would seem sensible to assume that bilinguals were at disadvantage given that most administered tests were in fact in their second language.  Thus, it should be evident that failure to control and measure for language proficiency and socio-economic differences has led to the compromising of both generalizability and validity of early studies.  Nonetheless, subsequent studies have made significant improvements in the process of understanding the effects of bilingualism on cognitive ability by carefully controlling for the aforementioned factors.

In contrast to early findings and opinions about bilingualism, subsequent studies and empirical body of literature supported the view that bilingualism does not lead to cognitive deficits (Petitto & Holowka, 2002).  In this respect, among some of the innovations in this area of research one can identify the introduction of the practice of investigating bilingual language skills and proficiency across two languages instead of just examining each language individually and in isolation from each other (Petitto & Holowka, 2002).  It is also interesting to notice that although some studies (Oller & Eilers, 2002; Bialystok & Fang, 2009; Portocarrero et al, 2007 Perani, et al., 2003) have found that individuals who are proficient in two languages tend to have smaller vocabularies in both languages compared to their monolingual counterparts, bilingual children’s vocabulary level is thought to be comparable to their monolingual peers if one include their skills in both languages. In this respect, should one combine the total amount of lexical items produced by children who are fluent in two languages, it could be argued that bilinguals reach language milestones approximately at around similar age that their monolingual counterparts reach (Petitto, et al., 2001; Holowka, et al., 2002). 

Other studies found that individuals who are bilingual tend to be relatively slow in retrieving lexical items compared to monolinguals (Roberts et al, 2002).  It is thought that this deficit is somewhat connected to the fact that bilinguals must sort through two different lexicons as means of accessing the right and intended words (Bialystock, 2009).  Nonetheless, it has also been found that process involved in negotiating between two language systems may in fact lead to a greater metalinguistic awareness in bilingual individuals (Bialystok & Majumder, 1998).  In this respect, it has been postulated that bilinguals tend to display an advanced type of understanding the fluid, dynamic and arbitrary aspects of language (Ianco-Warrall, 1972).  In addition, it has also been found that bilingual individuals show greater skills at making grammatically correct judgements, as well as showing greater phonemic awareness (Bialystock et al, 2003).  Thus, given that individuals who are fluent in two different languages show some strengths in some areas and weaknesses in other, one cannot simply assume that bilingualism can lead to cognitive and language problems. 

Perhaps more compelling, was the work carried out by Peal and Lamber (1962) who compared monolingual and bilingual children’s intelligence tests performance.  Contrary to what has been advocated by earlier studies, Peal and Lamber (1962) suitably controlled for bilinguals language proficiency by administering test which identified individuals who were proficient in both French and English.  Furthermore, they have also controlled for socio-economic status of monolingual and bilingual groups of children involved in the study.  Their study results revealed that bilinguals outperformed the monolinguals in both verbal and non-verbal tasks.  More specifically, they found that in tasks where mental or symbolic flexibility is required bilingual children seemed to perform considerably well compared to their monolingual counterparts.  Similarly, subsequent studies have also found that children who are fluent in two languages, when aged 4 and 5 years old tend to perform better than their monolingual counterparts in certain tasks (i.e. sorting cards according to colour /shape etc) during intelligence tests (Bialystok, 1999; Bialystok & Martin, 2004; Carlson & Meltzoff, 2008).  Such findings have demonstrated that bilinguals exhibit greater cognitive flexibility than their monolingual counterparts.        


In conclusion, it should be evident that despite earlier studies supporting the thesis that bilingualism could have negative repercussions on language and cognitive ability, subsequent findings corroborate precisely the opposite.  In this way, subsequent studies established that bilingualism can in fact enhance children cognitive abilities, including cognitive flexibility, and performance in verbal and non-verbal tasks in intelligence tests.  However, one should also note that the definition and the operationalisation of the concept bilingual is still in need for much scrutiny and theoretical sophistication given that this aspect has remained a substantially neglected area in both earlier and subsequent studies. 


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