research articles on bilingualism

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• Published: 17 April 2014

How does the bilingual experience sculpt the brain?

• Albert Costa 1 , 2 , 3 &
• Núria Sebastián-Gallés 1  

Nature Reviews Neuroscience volume  15 ,  pages 336–345 ( 2014 ) Cite this article

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• Cognitive control
• Neural circuits

The ability to speak two languages often marvels monolinguals, although bilinguals report no difficulties in achieving this feat. Here, we examine how learning and using two languages affect language acquisition and processing as well as various aspects of cognition. We do so by addressing three main questions. First, how do infants who are exposed to two languages acquire them without apparent difficulty? Second, how does language processing differ between monolingual and bilingual adults? Last, what are the collateral effects of bilingualism on the executive control system across the lifespan? Research in all three areas has not only provided some fascinating insights into bilingualism but also revealed new issues related to brain plasticity and language learning.

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Acknowledgements

The authors thank J. Abutalebi, D. Green, M. Burgaleta, P. Li, J. Corey, Y. Gilichinskaya and several members of the Center for Brain and Cognition at Pompeu Fabra University, Spain, for their comments on the manuscript. The authors are supported by grants from the European Community's Seventh Framework Programme (FP7/2007-2013): ERG grant agreement number 323961; Cooperation grant agreement number 613465 - AThEME), the Spanish Ministerio de Economía y Competitividad (PSI2011-23033; PSI2012-34071; Consolider-Ingenio2010-CDS-2007-00012) and the Catalan Government (SGR 2009–1521). N.S.G. received the prize ''ICREA Acadèmia'' for excellence in research, funded by the Generalitat de Catalunya.

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Albert Costa & Núria Sebastián-Gallés

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EDITORIAL article

Editorial: new approaches to how bilingualism shapes cognition and the brain across the lifespan: beyond the false dichotomy of advantage versus no advantage.

A correction has been applied to this article in:

Corrigendum: Editorial: New approaches to how bilingualism shapes cognition and the brain across the lifespan: beyond the false dichotomy of advantage versus no advantage

• Read correction

• 1 The MARCS Institute for Brain, Behaviour and Development, Western Sydney University, Penrith, NSW, Australia
• 2 School of Psychology and Clinical Language Sciences, University of Reading, Reading, United Kingdom
• 3 Centro de Investigación Nebrija en Cognición, Universidad Nebrija, Madrid, Spain
• 4 Department of Speech-Language-Hearing Sciences, Hofstra University, Hempstead, NY, United States

Editorial on the Research Topic New approaches to how bilingualism shapes cognition and the brain across the lifespan: Beyond the false dichotomy of advantage versus no advantage

For much of the 20 th century, bilingualism was thought to result in cognitive disadvantages. In recent decades, however, research findings have suggested that experience with multiple languages may yield cognitive benefits and even counteract age-related cognitive decline, possibly delaying the manifestation of symptoms of dementia. Subsequently, conflicting evidence has emerged, and this has led to questions regarding the robustness and generalizability of these claims. A heated debate has raged for more than a decade ( Antoniou, 2019 ), with certain research groups consistently finding support for a bilingual advantage, and others consistently finding none. The field has reached a stalemate, which has stifled research opportunities and the advancement of knowledge. In organizing the present Research Topic, we sought contributions describing new approaches needed to advance our field. These contributions help move the field beyond the traditional framing of bilingualism as a binary variable and toward approaches that capture the dynamic nature of effects relating to bilingualism and cognition.

New conceptualizations

One way of moving beyond traditional framing is to explore new conceptualizations of bilingualism, itself, and the relationship between bilingualism and cognition.

In her opinion piece, Bialystok likens the bilingual advantage debate to COVID-19 debates concerning which public health measures and mandates should (or should not) be implemented. She quotes virologist, Ian Mackay, who applied Reason's (1990) Swiss cheese model to COVID-19 risk mitigation by proposing that individual measures are imperfect (containing holes like a slice of Swiss cheese) and that only a multi-layered approach has sufficient redundancy built in to successfully offer protection from the risks at hand (similar to stacking slices of Swiss cheese so that the holes become covered). By adopting this metaphor, Bialystok is proposing that our field should move beyond simple conceptions concerning the relationship between bilingualism and cognition. Through this lens, bilingualism offers a layer of cognitive protection, but one which is porous rather than absolute. Bialystok's framing serves as a reminder that we, as a field, need to move beyond the “all or nothing” framing that has featured throughout the bilingual advantage debate over the past two decades.

The contribution from Sanches de Oliveira and Bullock Oliveira argues that the question of whether there are bilingual advantages in cognition is ill-formed and unanswerable. Bilingualism is a problematic category, according to the authors, because bilingualism and monolingualism are on a continuum rather than discrete, and languages and dialects are likewise on a continuum; what is more, a person's language proficiency is variable and skill- and context-specific, and full proficiency in any language is not even attainable, as one cannot have full proficiency in the vocabulary jargon of every possible activity. Cognition (and by extension cognitive advantages) are similarly problematic concepts, Sanches de Oliveira and Bullock Oliveira claim, partly because such concepts fail to account for the context-specific and thus variable nature of cognitive functioning.

Wagner et al. explore the questions of what it means to be bilingual, and what people consider to be a language. In doing so, they address the concern that many studies rely on participants' judgments of whether they themselves belong in the bilingual group or monolingual group. This self-assignment can be problematic because participants might vary considerably in what they believe constitutes a bilingual and even a language. In a survey of 528 participants, Wagner et al. observe a range of responses from participants when judging whether fictional speakers qualified as bilingual and fictional linguistic systems qualified as a language. Participants' definitions of bilingualism depended on several factors, including continued use of a language after immigrating and the presence of a writing system. Participants' definitions of a language depended on the presence of a writing system, similarity to other languages, and geographic breadth. Wagner et al. conclude that the variable and potentially inaccurate conceptions of bilingualism and language could contribute to some of the variable findings in the literature.

Chung-Fat-Yim et al. discuss the nuanced nature of attention, dividing this multi-faceted concept into sustained attention, selective attention, alternating attention, divided attention, and disengagement of attention. For each component of attention, the authors review relevant models from the psychology and neuroscience literature, as well as empirical research that has examined bilingualism's potential positive effects.

Voits et al. discuss the commonalities and complementarities between the bilingualism and cognitive aging literatures. Bilingualism tends to be reduced to a dichotomous trait, which misrepresents its status as a complex experience; other times it is overlooked as a contributory factor all together. These authors discuss why bilingualism is not recognized as a contributor to cognitive reserve. They also helpfully suggest how bilingualism can be better integrated into aging research in future work. A model of aging is needed that encompasses the contributions of lifestyle factors, one of which is likely to be bilingual experience.

New measures

Another way of moving beyond the stalemate debate surrounding bilingual benefits is to create new tasks, measures, and analyses.

Wu and Struys examine the influence of language dominance on bilingual word recognition. Uyghur-Chinese bilinguals completed lexical decision tasks administered in the L1 and L2, as well as a flanker task. Although bilinguals differed in their language dominance, all reported that they preferred reading in Chinese, their L2. Consequently, better performance was observed in their L2 than L1 on the lexical decision tasks. Further, those who had acquired their L2 earlier and had higher across-modality dominance in the L2 tended to recognize L2 words faster. The findings suggest that language dominance may be operationalized as a continuous or a categorical variable, and in doing so may exhibit effects not only for lexical recognition but also indirectly impacting domain-general contributions to recognition.

van den Berg et al. also investigate how individual bilingual experiences affect executive control in different contexts of language use. They tested bilingual university students, for whom they calculated a measure of language entropy for different contexts (university and non-university) by using a language background questionnaire. These language entropy measures were used as continuous predictors of the participants' performance in a color-shape switching task. Apart from collecting Reaction Times, pupil size was also measured as an objective index of set shifting abilities that are required for this task. The authors report that, while typical switching costs in RTs were not affected by entropy in either context, entropy did predict a switching cost in a non-university context when pupil dilation was studied. van den Berg et al. conclude that social diversity in bilinguals' experiences may indeed be linked to their executive control abilities, but this may depend on the exact social context and may be detectable in measures that are more sensitive than RT, such as pupil size.

Similarly, Freeman et al. focus on how quantified individual bilingual experiences affect performance in a non-linguistic task tapping executive control. Specifically, a sample of 146 Spanish-English heritage bilinguals were tested in a Stroop arrows task, from which the Stroop, facilitation and inhibition effects were calculated. Measures of individual experiences were used as predictors of these effects, including participants' sociolinguistic context (categorical), a composite continuous variable indexing L2 proficiency and exposure, as well as L2 age of acquisition, L2 proficiency and a measure of non-verbal cognitive reasoning, all continuous factors. The authors report a rich pattern of findings which converged in that increased bilingual experiences and cognitive skills led to increased abilities of focusing on relevant stimuli while ignoring irrelevant ones. These findings were also modulated by the sociolinguistic environment of the individuals, suggesting that any effects of bilingualism on cognition should be viewed in relation to the contexts that bilinguals find themselves in.

Grant et al.'s contribution follows on the same path of avoiding a binary monolingual-bilingual comparison and employing a seldom-used but meaningful and sensitive neural measure. Specifically, participants listened to speech-in-noise in their L1 and L2; the continuous independent variable of L2 age of acquisition and the dependent variable of EEG-measured alpha power were used. Findings indicate an increased alpha power when listening in the L2 and when the participant had an older L2 age of acquisition.

In a similar vein, Marin-Marin et al. turn their attention to the effects of bilingualism on brain structure, by using a measure of bilingual experiences as a predictor of regional gray matter volume in a group of Catalan-Spanish bilinguals that were immersed in a bilingual environment. They report non-linear volumetric fluctuations in a series of cortical and subcortical regions that have been linked to speech processing and language control. The authors argue that their pattern of results are corroborative of theoretical suggestions for dynamic, non-linear effects of bilingualism on the adult brain.

Finally, Dash et al. attempt to advance modeling bilingualism as a continuous variable. They show that a multifactorial approach to different dimensions of bilingual study may lead to a better understanding of the role of bilingualism on cognitive performance. Rather than reducing variability or treating it as problematic, these authors argue that variability needs to be embraced in bilingual profiles if we are to generalize the results of individual studies to the wider literature.

Future directions

Taken together, the articles within this Research Topic provide suggestions concerning how our field might move beyond the entrenched positions that have characterized the bilingual advantage debate for more than a decade. We are excited by the ambitious and rigorous studies that will emerge in coming years to advance understanding of how experience with multiple languages interacts with other variables to affect cognition, the structure and function of the brain, and aging. There remains a need for detailed theoretical models that generate testable predictions in order for us to understand what types of bilingual experiences are more (or less) likely to show plasticity effects in a given domain. To achieve this, it is necessary to pay attention to how bilingualism is conceptualized and to methodological nuances in experimental designs, such as differences in tasks used and in the components of cognition they measure. By focusing on these aspects, we believe that this Research Topic offers a window into how knowledge can advance within our field, specifically concerning how bilingualism affects cognition and the brain.

Author contributions

MA, CP, and SRS contributed equally to the writing of this editorial article. All authors contributed to the article and approved the submitted version.

This work was funded by the Australian Research Council, Grant Number: DP190103067.

Conflict of interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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Antoniou, M. (2019). The advantages of bilingualism debate. Annu. Rev. Linguist. 5, 395–415. doi: 10.1146/annurev-linguistics-011718-011820

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Keywords: bilingualism, cognition, brain, advantage, new approaches

Citation: Antoniou M, Pliatsikas C and Schroeder SR (2023) Editorial: New approaches to how bilingualism shapes cognition and the brain across the lifespan: Beyond the false dichotomy of advantage versus no advantage. Front. Psychol. 14:1149062. doi: 10.3389/fpsyg.2023.1149062

Received: 20 January 2023; Accepted: 25 January 2023; Published: 07 February 2023.

Edited and reviewed by: Sara Palermo , University of Turin, Italy

Copyright © 2023 Antoniou, Pliatsikas and Schroeder. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) . The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

† These authors have contributed equally to this work

Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

Cognitive Consequences of Bilingualism and Multilingualism: Cross-Linguistic Influences

• Published: 12 April 2021
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Bilingualism and multilingualism are common in almost all communities worldwide today. Research studies on the psycholinguistics of bilingualism and multilingualism in East Asia region has developed tremendously in the past 20 years. Along with the new methodologies, innovative approaches, and the development of those state-of-the-art technologies (Altarriba and Heredia (eds) in An introduction to bilingualism: principles and processes, Routledge, 2018), a lot of new research findings on this line of research have been reported.

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Yip, M.C.W. Cognitive Consequences of Bilingualism and Multilingualism: Cross-Linguistic Influences. J Psycholinguist Res 50 , 313–316 (2021). https://doi.org/10.1007/s10936-021-09779-y

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Article contents

Bilingualism and multilingualism from a socio-psychological perspective.

• Tej K. Bhatia Tej K. Bhatia Department of Linguistics, Syracuse University
• https://doi.org/10.1093/acrefore/9780199384655.013.82
• Published online: 28 June 2017

Bilingualism/multilingualism is a natural phenomenon worldwide. Unwittingly, however, monolingualism has been used as a standard to characterize and define bilingualism/multilingualism in linguistic research. Such a conception led to a “fractional,” “irregular,” and “distorted” view of bilingualism, which is becoming rapidly outmoded in the light of multipronged, rapidly growing interdisciplinary research. This article presents a complex and holistic view of bilinguals and multilinguals on conceptual, theoretical, and pragmatic/applied grounds. In that process, it attempts to explain why bilinguals are not a mere composite of two monolinguals. If bilinguals were a clone of two monolinguals, the study of bilingualism would not merit any substantive consideration in order to come to grips with bilingualism; all one would have to do is focus on the study of a monolingual person. Interestingly, even the two bilinguals are not clones of each other, let alone bilinguals as a set of two monolinguals. This paper examines the multiple worlds of bilinguals in terms of their social life and social interaction. The intricate problem of defining and describing bilinguals is addressed; their process and end result of becoming bilinguals is explored alongside their verbal interactions and language organization in the brain. The role of social and political bilingualism is also explored as it interacts with individual bilingualism and global bilingualism (e.g., the issue of language endangerment and language death).

Other central concepts such as individuals’ bilingual language attitudes, language choices, and consequences are addressed, which set bilinguals apart from monolinguals. Language acquisition is as much an innate, biological, as social phenomenon; these two complementary dimensions receive consideration in this article along with the educational issues of school performance by bilinguals. Is bilingualism a blessing or a curse? The linguistic and cognitive consequences of individual, societal, and political bilingualism are examined.

• defining bilinguals
• conceptual view of bilingualism
• becoming bilingual
• social networks
• language organization of bilinguals
• the bilingual mind
• bilingual language choices
• language mixing
• code-mixing/switching
• bilingual identities
• consequences of bilingualism
• bilingual creativity
• and political bilingualism

1. Understanding Multilingualism in Context

In a world in which people are increasingly mobile and ethnically self-aware, living with not just a single but multiple identities, questions concerning bilingualism and multilingualism take on increasing importance from both scholarly and pragmatic points of view. Over the last two decades in which linguistic/ethnic communities that had previously been politically submerged, persecuted, and geographically isolated, have asserted themselves and provided scholars with new opportunities to study the phenomena of individual and societal bilingualism and multilingualism that had previously been practically closed to them. Advances in social media and technology (e.g., iPhones and Big Data Capabilities) have rendered new tools to study bilingualism in a more naturalistic setting. At the same time, these developments have posed new practical challenges in such areas as language acquisition, language identities, language attitudes, language education, language endangerment and loss, and language rights.

The investigation of bi- and multilingualism is a broad and complex field. Unless otherwise relevant on substantive grounds, the term “bilingualism” in this article is used as an all-inclusive term to embody both bilingualism and multilingualism.

2. Bilingualism as a Natural Global Phenomenon: Becoming Bilingual

Bilingualism is not entirely a recent development; for instance, it constituted a grassroots phenomenon in India and Africa since the pre-Christian era. Contrary to a widespread perception, particularly in some primarily monolingual countries—for instance, Japan or China—or native English-speaking countries, such as the United States, bilingualism or even multilingualism is not a rare or exceptional phenomenon in the modern world; it was and it is, in fact, more widespread and natural than monolingualism. The Ethnologue in the 16th edition ( 2009 , http://www.ethnologue.com/show_country.asp?name=lb ) estimates more than seven thousand languages (7,358) while the U.S. Department of States recognizes only 194 bilingual countries in the world. There are approximately 239 and 2,269 languages identified in Europe and Asia, respectively. According to Ethnologue , 94% of the world’s population employs approximately 5% of its language resources. Furthermore, many languages such as Hindi, Chinese, Arabic, Bengali, Punjabi, Spanish, and Portuguese are spoken in many countries around the globe. Such a linguistic situation necessitates people to live with bilingualism and/or multilingualism. For an in-depth analysis of global bilingualism, see Bhatia and Ritchie ( 2013 ).

3. Describing Bilingualism

Unlike monolingualism, childhood bilingualism is not the only source and stage of acquiring two or more languages. Bilingualism is a lifelong process involving a host of factors (e.g., marriage, immigration, and education), different processes (e.g., input conditions, input types, input modalities and age), and yielding differential end results in terms of differential stages of fossilization and learning curve (U-shape or nonlinear curve during their grammar and interactional development). For this reason, it does not come as a surprise that defining, describing, and categorizing a bilingual is not as simplistic as defining a monolingual person. In addition to individual bilingualism, social and political bilingualism adds yet other dimensions to understanding bilingualism. Naturally then, there is no universally agreed upon definition of a bilingual person.

Bilingual individuals are subjected to a wide variety of labels, scales, and dichotomies, which constitute a basis of debates over what is bilingualism and who is a bilingual. Before shedding light on the complexity of “individual” bilingualism, one should bear in mind that the notion of individual bilingualism is not devoid of social bilingualism, or an absence of a shared social or group grammar. The term “individual” bilingualism by no means refers to idiosyncratic aspects of bilinguals, which is outside the scope of this work.

Relying on a Chomskyan research paradigm, bilingualism is approached from the theoretical distinction of competence vs. performance (actual use). Equal competency and fluency in both languages—an absolute clone of two monolinguals without a trace of accent from either language—is one view of a bilingual person. This view can be characterized as the “maximal” view. Bloomfield’s definition of a bilingual with “a native-like control of two languages” attempts to embody the “maximal” viewpoint (Bloomfield, 1933 ). Other terms used to describe such individuals are “ambilinguals” or “true bilinguals.” Such bilinguals are rare, or what Valdes terms, “mythical bilingual” (Valdes, 2001 ). In contrast to maximal view, a “minimal” view contends that practically every one is a bilingual. “That is no one in the world (no adult, anyway) which does not know at least a few words in languages other than the maternal variety” (Edwards, 2004/2006 ). Diebold’s notion of “Incipient bilingualism”—that is, exposure to two languages—belongs to the minimal view of bilingualism (Diebold, 1964 ). While central to the minimalist viewpoint is the onset point of the process of becoming a bilingual, the main focus of the maximalist view is the end result, or termination point, of language acquisition. In other words, the issue of degree and the end state of second language acquisition is at the heart of defining the concept of bilingualism.

Other researchers such as Mackey, Weinreich, and Haugen define bilingualism to capture language use of bilinguals’ verbal behavior. For Haugen, bilingualism begins when the speakers of one language produce complete meaningful utterances in the second language (Haugen, 1953 ; Mackey, 2000 ; Weinrich, 1953 ). Mackey, on the other hand, defines bilingualism as an “alternate use of two or more languages” (Mackey, 2000 ). Observe that the main objective of the two definitions is to focus on language use rather the degree of language proficiency or equal competency in two languages.

The other notable types of bilingualism identified are as follows: Primary/Natural bilingualism in which bilingualism is acquired in a natural setting without any formal training; Balanced bilingualism that develops with minimal interference from both languages; Receptive or Passive bilingualism wherein there is understanding of written and/or spoken proficiency in second language but an inability to speak it; Productive bilingualism then entails an ability to understand and speak a second language; Semilingualism, or an inability to express in either language; and Bicultural bilingualism vs. Monocultural bilingualism. The other types of bilingualism, such as Simultaneous vs. Successive bilingualism (Wang, 2008 ), Additive vs. Subtractive bilingualism (Cummins, 2000 ), and Elite vs. Folk bilingualism (Skutnabb-Kangas, 1981 ), will be detailed later in this chapter. From this rich range of scales and dichotomies, it becomes readily self-evident that the complexity of bilingualism and severe limitation of the “fractional” view of bilingualism that bilinguals are two monolinguals in one brain. Each case of bilingualism is a product of different sets of circumstances and, as a result, no two bilinguals are the same. In other words, differences in the context of second language acquisition (natural, as in the case of children) and proficiency in spoken, written, reading, and listening skills in the second language, together with the consideration of culture, add further complexity to defining individual bilingualism.

3.1 Individual Bilingualism: A Profile

The profile of this author further highlights the problems and challenges of defining and describing a bilingual or multilingual person. The author, as an immigrant child growing up in India, acquired two languages by birth: Saraiki—also called Multani and Lahanda, spoken primarily in Pakistan—and Punjabi, which is spoken both in India and Pakistan. Growing up in the Hindi-speaking area, he learned the third language Hindi-Urdu primarily in schools; and his fourth language, English, primarily after puberty during his higher education in India and the United States. He cannot write or read in Saraiki but can read Punjabi in Gurmukhi script, and he cannot write with the same proficiency. He has native proficiency in speaking, listening, reading, and writing. A close analysis of his bilingualism reveals that no single label or category accounts for his multifaceted bilingualism/multilingualism. Interestingly, his self-assessment finds him linguistically least secured in his two languages, which he acquired at birth. Is he a semilingual without a mother tongue? No matter how challenging it is to come to grips with bilingualism and, consequently, develop a “holistic” view of bilingualism, it is clear that a bilingual person demonstrates many complex attributes rarely seen in a monolingual person. See Edwards ( 2004/2006 ) and Wei ( 2013 ) for more details. Most important, multiple languages serve as a vehicle to mark multiple identities (e.g., religious, regional, national, ethnic, etc.).

3.2 Social Bilingualism

While social bilingualism embodies linguistic dimensions of individual bilingualism, a host of social, attitudinal, educational, and historical aspects of bilingualism primarily determine the nature of social bilingualism. Social bilingualism refers to the interrelationship between linguistic and non-linguistic factors such as social evaluation/value judgements of bilingualism, which determine the nature of language contact, language maintenance and shift, and bilingual education among others. For instance, in some societies, bilingualism is valued and receives positive evaluation and is, thus, encouraged while in other societies bilingualism is seen as a negative and divisive force and is, thus, suppressed or even banned in public and educational arenas. Compare the pattern of intergenerational bilingualism in India and the United states, where it is well-known that second or third-generation immigrants in the United States lose their ethnic languages and turn monolinguals in English (Fishman, Nahirny, Hofman, & Hayden, 1966 ). Conversely, Bengali or Punjabi immigrants living in Delhi, generation after generation, do not become monolinguals in Hindi, the dominant language of Delhi. Similarly, elite bilingualism vs. folk bilingualism has historically prevailed in Europe, Asia, and other continents and has gained a new dimension in the rapidly evolving globalized society. As aristocratic society patronized bilingualism with French or Latin in Europe, bilingualism served as a source of elitism in South Asia in different ages of Persian and English. Folk bilingualism is often the byproduct of social dominance and imposition of a dominant group. While elite bilingualism is viewed as an asset, folk bilingualism is seen as problematic both in social and educational arenas (Skutnabb-Kangas, 1981 ). One of the outcomes of a stable elite and folk bilingualism is diglossia (e.g., Arabic, German, Greek, and Tamil) where both High (elite) and Low (colloquial) varieties of a language—or two languages with High and Low social distinctions—coexist (e.g., French and English diglossia after the Norman conquest (Ferguson, 1959 ). Diasporic language varieties have been examined by Clyne and Kipp ( 1999 ) and Bhatia ( 2016 ). Works by Baker and Jones ( 1998 ) show how bilinguals belong to communities of variable types due to accommodation (Sachdev & Giles, 2004/2006 ), indexicality (Eckert & Rickford, 2001 ), social meaning of language attitudes (Giles & Watson, 2013 ; Sachdev & Bhatia, 2013 ), community of practice, and even imagined communities.

3.3 Political Bilingualism

Political bilingualism refers to the language policies of a country. Unlike individual bilingualism, categories such as monolingual, bilingual, and multilingual nations do not reflect the actual linguistic situation in a particular country (Edwards, 1995 , 2004/2006 ; Romaine, 1989/1995 ). Canada, for instance, is officially recognized as a bilingual country. This means that Canada promotes bilingualism as a language policy of the country as well as in Canadian society as a whole. By no means does it imply that most speakers in Canada are bilinguals. In fact, monolingual countries may reflect a high degree of bilingualism. Multilingual countries such as South Africa, Switzerland, Finland and Canada often use one of the two approaches—“Personality” and “Territorial”—to ensure bilingualism. The Personality principle aims to preserve individual rights (Extra & Gorter, 2008 ; Mackey, 1967 ) while the Territorial principle ensures bilingualism or multilingual within a particular area to a variable degree, as in the case of Belgium. In India, where 23 languages are officially recognized, the government’s language policies are very receptive to multilingualism. The “three-language formula” is the official language policy of the country (Annamalai, 2001 ). In addition to learning Hindi and English, the co-national languages, school children can learn a third language spoken within or outside their state.

4. The Bilingual Mind: Language Organization, Language Choices, and Verbal Behavior

Unlike monolinguals, a decision to speak multiple languages requires a complex unconscious process on the part of bilinguals. Since a monolingual’s choice is restricted to only one language, the decision to choose a language is relatively simple involving, at most, the choice of an informal style over a formal style or vice versa. However, the degree and the scale of language choice are much more complicated for bilinguals since they need to choose not only between different styles but also between different languages. It is a widely held belief, at least in some monolingual speech communities, that the process of language choice for bilinguals is a random one that can lead to a serious misunderstanding and a communication failure between monolinguals and bi- and multilingual communities (see pitfalls of a sting operation by a monolingual FBI agent (Ritchie & Bhatia, 2013 )). Such a misconception of bilingual verbal behavior is also responsible for communication misunderstandings about social motivations of bilinguals’ language choices by monolinguals; for example, the deliberate exclusion or sinister motives on the part of bilinguals when their language choice is different from a monolingual’s language. A number of my international students have reported that on several occasions monolingual English speakers feel compelled to remind them that they are in America and they should be using English, rather than say Chinese or Arabic, with countrymen/women.

Now let us examine some determinants of language choice by bilinguals. Consider the case of this author’s verbal behavior and linguistic choices that he normally makes while interacting with his family during a dinner table conversation in India. He shares two languages with his sisters-in-law (Punjabi and Hindi) and four languages with his brothers (Saraiki, Punjabi, Hindi, and English). While talking about family matters or other informal topics, he uses Punjabi with his sisters-in-law but Saraiki with his brothers. If the topic involves ethnicity, then the entire family switches to Punjabi. Matters of educational and political importance are expressed in English and Hindi, respectively. These are unmarked language choices, which the author makes unconsciously and effortlessly with constant language switching depending on participants, speech events, situations, or other factors. Such a behavior is largely in agreement with the sociolinguistic Model of Markedness, which attempts to explain the sociolinguistic motivation of code-switching by considering language choice as a means of communicating desired group membership, or perceived group memberships, and interpersonal relationships (Pavlenko, 2005 ).

Speaking Sariki with brothers and Punjabi with sister-in-laws represent unconscious and unmarked choices. Any shift to a marked choice is, of course, possible on theoretical grounds; however, it can take a serious toll in terms of social relationships. The use of Hindi or English during a general family dinner conversation (i.e., a “marked” choice) will necessarily signal social distancing and fractured relations.

Languages choice is not as simple as it seems at first from the above example of family conversation. In some cases, it involves a complex process of negotiation. Talking with a Punjabi-Hindi-English trilingual waiter in an Indian restaurant, the choice of ethnic language, Punjabi, by a customer such as this author may seem to be a natural choice at first. Often, it is not the case if the waiter refuses to match the language choice of the customer and replies in English. The failure to negotiate a language in such cases takes an interesting turn of language mismatching before a common language of verbal exchange is finally agreed upon; often, it turns out to be a neutral and prestige language: English. See Ritchie and Bhatia ( 2013 ) for further details. When the unmarked choice is not clear, speakers tend to use code-switching in an exploratory way to determine language choice and thus restore a social balance.

During a speech event, language choice is not always static either. If the topic of conversation shifts from a casual topic to a formal topic such as education, a more suitable choice in this domain would be English; subsequently, a naturally switch to English will take place. In other words, “complementarity” language domains or language-specific domain allocation represent the salient characteristics of bilingual language choice. The differential domain allocation manifests itself in the use of “public” vs. “private” language by bilinguals, which is central to bilingual verbal repertoire (Ritchie & Bhatia, 2013 ). Often the role of expressing emotions or one’s private world is best played by the bilingual’s mother tongue rather than by the second or prestige/distant language. Research on bilingualism, emotions, and autobiographical memory accounts of bilinguals shows that an account of emotional events is qualitatively and quantitatively different when narrated in one’s mother tongue than in a distant second language (Devaele, 2010 ; Pavlenko, 2005 ). While the content of an event can be narrated equally well in either language, the emotional experience/pain is best described in the first language of the speaker. Particularly, bilingual parents use their first language for terms of endearment for their children. Their first language serves as the best vehicle for denoting emotions toward their children than any other language in their verbal repertoire. Taboo topics, on the other hand, favor the second or a distant language.

Any attempt to characterize the bilingual mind must account for the following three natural aspects of bilingual verbal behavior: (1) Depending upon the communicative circumstances, bilinguals swing between the monolingual and bilingual language modes; (2) Bilinguals have an ability to keep two or more languages separate whenever needed; and (3) More interestingly, they can also carry out an integration of two or more languages within a speech event.

4.1 Bilingual Language Modes

Bilinguals are like a sliding switch who can move between one or more language states/modes as required for the production, comprehension, and processing of verbal messages in a most cost-effective and efficient way. If bilinguals are placed in a predominantly monolingual setting, they are likely to activate only one language; while in a bilingual environment, they can easily shift into a bilingual mode to a differential degree. The activation or deactivation process is not time consuming. In a bilingual environment, this process usually does not require bilinguals to take more than a couple of milliseconds to swing into a bilingual language mode and revert back to a monolingual mode with the same time efficiency. However, under unexpected circumstances (e.g., caught off-guard by a white Canadian speaking an African language in Canada) or under emotional trauma or cultural shock, the activation takes considerable time. In the longitudinal study of his daughter, Hildegard, reported that Hildegard, while in Germany, came to tears at one point when she could not activate her mother tongue, English (Leopard, 1939–1950 ). The failure to ensure natural conditions responsible for the activation of bilingual language mode is a common methodological shortcoming of bilingual language testing, see Grosjean ( 2004 / 2006 , 2010 ). An in-depth review of processing cost involved in the language activation-deactivation process can be found in Meuter ( 2005 ). Do bilinguals turn on their bilingual mode, even if only one language is needed to perform a task? Recent research employing an electrophysiological and experimental approach shows that both languages compete for selection even if only one language is needed to perform a task (Martin, Dering, Thomas, & Thierry, 2009 ; Hoshino & Thierry, 2010 ). For more recent works on parallel language activation and language competition in speech planning and speech production, see Blumenfeld and Marian ( 2013 ). In other words, the potential of activation and deactivation of language modes—both monolingual and bilingual mode—hold an important key to bilingual’s language use.

4.2 Bilingual Language Separation and Language Integration

In addition to language activation or deactivation control phenomena, the other two salient characteristics of bilingual verbal behavior are bilinguals’ balanced competence and capacity to separate the two linguistic systems and to integrate them within a sentence or a speech event. Language mixing is a far more complex cognitive ability than language separation. Yet, it is also very natural to bilinguals. Therefore, it is not surprising to observe the emergence of mixed systems such as Hinglish, Spanglish, Germlish, and so on, around the globe. Consider the following utterances:

Such a two-faceted phenomenon is termed as code-mixing (as in 1 and 2) and code-switching (as in 3). Code-mixing (CM) refers to the use of various linguistic units—words, phrases, clauses, and sentences—primarily from two participating grammatical systems within a sentence. While CM is intra-sentential, code-switching (CS) is an inter-sentential phenomenon. CM is constrained by grammatical principles and is motivated by socio-psychological factors. CS, on the other hand, is subject to discourse principles and is also motivated by socio-psychological factors.

Any unified treatment of the bilingual mind has to account for the language separation (i.e., CS) and language integration (CM) aspects of bilingual verbal competence, capacity, use, and creativity. In that process, it needs to address the following four key questions, which are central to an understanding the universal and scientific basis for the linguistic creativity of bilinguals.

Is language mixing a random or a systematic phenomenon?

What motivates bilinguals to mix and alternate two languages?

What is the social evaluation of this mixing and alternation?

What is the difference between code-mixing or code-switching and other related phenomena?

I. Language mixing as a systematic phenomenon

Earlier research from the 1950s–1970s concluded that CM is either a random or an unsystematic phenomenon. It was either without subject to formal syntactic constraints or is subject only to “irregular mixture” (Labov, 1971 ). Such a view of CM/CS is obsolete since late the 20th century . Recent research shows that CM/CS is subject to formal, functional, and attitudinal factors. Studies of formal factors in the occurrence of CM attempt to tap the unconscious knowledge of bilinguals about the internal structure of code-mixed sentences. Formal syntactic constraints on the grammar of CM, such as The Free Morpheme Constraint (Sankoff & Poplack, 1981 ); The Closed Class Constraint (Joshi, 1985 ), within the Generative Grammar framework; and The Government Constraint and the Functional Head Constraint within the non-lexicalist generative framework, demonstrate the complexity of uncovering universal constraints on CM; for details, see Bhatia and Ritchie ( 2009 ). Recently, the search for explanations of cross-linguistic generalizations about the phenomenon of CM, specifically in terms of independently justified principles of language structure and use, has taken two distinct forms. One approach is formulated in terms of the theory of linguistic competence within the framework of Chomsky’s Minimalist Program (MacSwan, 2009 ). The other approach—as best exemplified by the Matrix Language Frame (MLF) model (Myers-Scotton & Jake, 2001 ) is grounded in the theory of sentence production, particularly that of Levelt ( 1989 ). Herring and colleagues test the strengths and weaknesses of both a Minimalist Program approach and the MLF approach on explanatory grounds based on switches between determiner and their noun complements drawn from Spanish-English and Welsh-English data (Herring, Deuchar, Couto, & Quintanilla, 2010 ). Their work lends partial support to the two approaches.

II. Motivations for language mixing

While research on the universal grammar of CM attempts to unlock the mystery of the systematic nature of CM on universal grounds, it does not attempt to answer Question (II), namely, the “why” aspect of CM. The challenge for linguistic research in the new millennium is to separate grammatical constraints from those motivated by, or triggered by, socio-pragmatic factors or competence. Socio-pragmatic studies of CM reveal the following four factors, which trigger CM/CS: (1) the social roles and relationships of the participants (e.g., dual/multiple identities; social class); (2) situational factors (discourse topic and language domain allocation); (3) message-intrinsic consideration; (4) language attitudes, including social dominance and linguistic security. See Ritchie and Bhatia ( 2013 ) and Myers-Scotton ( 1998 ) for further details. The most commonly accepted rule is that language mixing signals either a change or a perceived change by speaker in the socio-psychological context of a speech event. In essence, CM/CS is motivated by the consideration of “optimization,” and it serves as an indispensable tool for meeting creative and innovative needs of bilinguals (Bhatia, 2011 ). A novel approach provides further insights into a discourse-functional motivation of CM, namely, coding of less predictable, high information-content meanings in one language and more predictable, lower information-content meanings in another language (Myslin & Levy, 2015 ).

III. Social evaluation of language mixing

Now let us return to Question (III). From the discussion of Questions (I and II), it is self-evident that complexity and multifaceted creativity underlies CM/CS in bilingual communication. Surprisingly, though, the social evaluation of a mixed system is largely negative. Even more interestingly, bilinguals themselves do not have a positive view of language mixing. It is the widely held belief on the part of the “guardians” of language (including the media) and puritans that any form of language mixing is a sign of unsystematic or decadent form of communication. Bilinguals are often mocked for their “bad” and “irregular” linguistic behavior. They are often characterized as individuals who have difficulty expressing themselves. Other labels such as “lazy” and “careless” are also often bestowed upon them. Furthermore, the guardians of language often accused them of destroying their linguistic heritage. For these reasons, it is not surprising that even bilinguals themselves become apologetic about their verbal behavior. They blame mixing on “memory lapse,” among other things, and promise to correct their verbal behavior, vowing not to mix languages. In spite of this, they cannot resist language mixing!

Table 1 illustrates the anomaly between the scientific reality of language mixing and its social perception. Social perception translates into the negative evaluation of mixed speech.

Table 1. Language Mixing (CM/CS) Anomaly (Adapted from Bhatia & Ritchie, 2008 , p. 15).

Backlash to mixing is not just restricted to societies and bilinguals; even governments get on the bandwagon. Some countries, such as the newly freed countries of the ex-Soviet Union and France, regulate or even ban mixing either by appointing “language police” or by passing laws to wipe out the perceived negative effects of “bad language” in the public domain. Asia is not an exception in this regard. A case in point is a recent article by Tan ( 2002 ) reporting that the Government of Singapore has banned the movie Talk Cock because it uses a mixed variety of English, called Singlish. Linguistic prescriptivism clearly played a central role in the decision. In spite of the near-universal negative evaluation associated with CM/CS, the benefits rendered by language mixing by far outweigh its negative perception, which, in turn, compels the unconscious mind of bilinguals to mix and switch in order to yield results that cannot be rendered by a single/puritan language use; for a typology of bilingual linguistic creativity, and socio-psychological motivations, see Ritchie and Bhatia ( 2013 ).

IV. Language mixing and other related phenomena

Returning to the fourth question, it should be noted that CM/CS is quite distinct from linguistic borrowing. The primary function of linguistic borrowing is to fill a lexical gap in a borrower’s language (e.g., Internet, satellite). Furthermore, with borrowing, the structure of the host language remains undisturbed. However, CM requires complex integrity of two linguistic systems/grammar within a sentence, which may yield a new grammar. Other mixed systems, such as pidgin and creole languages, often fail to match the complexity and creativity of CM/CS. The distinction between code-mixing and code-switching is controversial for a number of reasons, particularly the integration of the participating grammar’s intrasententially details; see Bhatia and Ritchie ( 2009 ). Additionally, Deuchar and Stammers ( 2016 ) claim that code-switches and borrowings are distinct on the basis of frequency and degree of integration. Specifically, only the former are low in both frequency and integration. For details about contrasting and comparing different positions on this issue, see Myslin & Levy ( 2015 ); Poplack and Meechan ( 1998 ); and Lakshmanan, Balam, and Bhatia ( 2016 ). Furthermore, there is a debatable distinction between CM and Translanguaging (Garcia & Wei, 2014 ).

5. Bilingual Language Development: Nature vs. Nurture

Beyond innateness (e.g., nature, Biolinguistic and Neurological basis of language acquisition), social factors play a critical play in the language development of bilinguals. As pointed out earlier, describing and defining bilingualism is a formidable task. This is due to the fact that attaining bilingualism is a lifelong process; a complex array of conditions gives rise to the development of language among bilinguals. Based on the recommendation of educators, among others, bilingual families usually adopt a “One-Parent/One-Language” strategy with different combinations, such as language allocation based on time and space; for example, using one language in the morning and other in the evening or one language in the kitchen and another in the living room. This is done to maintain minority language. In spite of their obvious potential benefits for language maintenance, such strategies fall short in raising bilingual and bicultural children for a number of reasons, including imparting pragmatic and communicative competence and providing negative and positive evidence to children undergoing heritage language development with sociolinguistically real verbal interactional patterns (Bhatia & Ritchie, 1995 ). Therefore, De Houwer ( 2007 ) rightly points out that it is important for children to be receiving language input in the minority language from both parents at home. This also represents a common practice in non-Western societies in Asia (e.g., India) and Africa (e.g., Nigeria) where both parents, including members of the joint family minority languages, speak in their minority language.

While raising bilingual children does not pose any serious challenge for majority children (e.g., English-speaking children learning French in Canada), it is a different story for minority or heritage children. Sadly, a complex mix of political and social bilingualism leads heritage/minority parents, who themselves experience adverse discrimination in social and work settings, simply to prohibit the use of minority languages in family and educational environments. This practice, no matter how well intended, often results in negative school performance and emotional problems for minority children.

6. Simultaneous vs. Sequential Childhood Bilingualism

Broadly speaking, childhood bilingualism can manifest itself in two distinct patterns: (1) Simultaneous bilingualism and (2) Sequential bilingualism. A child being exposed to two languages to more or less to the same degree from birth onward is described as a simultaneous bilingual; conversely, a child being exposed to one language first followed by a second language, with the latter coming after the age of five, is referred to as sequential bilingual. Sequential bilingualism takes place either in schools or in peer groups and/or family settings. Surely, sequential bilingualism can persist throughout the adulthood. How is early bilingualism different from late bilingualism? Research on sequential and adult language acquisition shows that the pattern of sequential/successive language acquisition falls somewhere in the middle of the continuum between a simultaneous bilingual and an adult language learner.

7. Adult Bilingualism: UG and Native Language Dominance

Why is the task of learning a second language by adults more difficult and time consuming than by children? In spite of considerable motivation and effort, why do adults fall short of achieving native-like competency in their target language? Why do even very competent and balanced bilinguals speak with an “accent”? The Critical Period Hypothesis by Lenneberg ( 1967 ) attempts to answer these questions, and it is sensitive to age (Lenneberg, 1967 ). Children are better equipped to acquire languages because their brains are more “plastic” before they hit maturity. They have access to UG, to which adults have either no access or only partial access. Afterward, the loss of plasticity results in the completion of lateralization of language function in the left hemisphere. Even though adults are more cognitively developed and exhibit a high degree of aptitude, they have to rely on their native language (L1 transference—including “foreign accent” together with morphological features) in the process of learning a second language (Gass, 1996 ). Then there comes a time when their ultimate attainment of L2 falls short of the native language target, termed “fossilization” stage. No amount of training allows them to bypass this stage to free themselves from second language errors. Siegel, for instance, offers an alternative explanation of the language attainment state termed fossilization in second language acquisition research—a stage of falling short of attaining a native-speaker end grammar (Siegel, 2003 ). He argues that fossilization is not biologically driven but is the reflection of learners’ decisions not to clone the native speaker’s norm in order to index their own identity. Some researchers believe that this stage does not have a biological basis; instead, it is the result of bilingual, dual, or multiple identities. Adult learners are not ready to give up their identity and, as a result, this prevents them from having a perfect native-like competency of L2. For alternative theories of language acquisition, see, for example, a usage-based approach by Tomasello ( 2003 ); and the Dynamic System Theory by De Bot, Wander, and Verspoor ( 2007 ).

The differential competencies, as evident from the different types of adult bilinguals, can be accounted for primarily on sociolinguistic grounds. For instance, gender or the period of residency in a host country yields the qualitative and quantitative differences in bilingual language acquisition. Factors such as access to workplace, education, relationship, social networks, exogamic marriage, religion, and other factors lead to differential male and female bilingualism in qualitative grounds (Piller & Pavlenko, 2004/2006 ). Additionally, learners’ type, their aptitude, and attitude also contribute to a variable degree of language learning curves. Instrumental learners who learn a second language for external gains tend to lag behind Integrative learners who aim at integration with the target culture. Similarly, the Social Accommodation Theory (Sachdev & Giles, 2004/2006 ) attempts to explain differences in language choices and consequences on one hand and the social evaluation of speech (good vs. bad accents) on the other, which influence the social-psychological aspects of bilingual verbal interaction in different social settings (Altarriba & Moirier, 2004/2006 ; Lippi-Green, 2012 ).

8. Effects of Bilingualism

Until the middle of the 20th century in the United States, researchers engaged in examining the relationship between intelligence and bilingualism concluded that bilingualism has serious adverse effects on early childhood development. Such findings led to the development of the “factional” view of bilingualism, which was grounded in a flawed monolingual perspective on the limited linguistic capacity of the brain on one hand and the Linguistic Deficit Hypothesis on the other.

Their line of argument was that crowding the brain with two languages leads to a variety of impairments in both the linguistic and the cognitive abilities of the child. Naturally, then, they suggested that bilingual children not only suffer from semilingualism (i.e., lacking proficiency both in their mother tongue and the second language) and stuttering, etc., but also from low intelligence, mental retardation, left handedness, and even schizophrenia.

It took more than half a century before a more accurate and positive view of bilingualism emerged. The main credit for this goes to the pioneering work of Peal and Lambert ( 1962 ), which revealed the actual benefits of bilingualism. The view of bilingualism that subsequently emerged can be characterized as the Linguistic Augmentation Hypothesis (Peal & Lambert, 1962 ). Peal and Lambert studied earlier balanced bilingual children and controlled for factors such as socioeconomic status. Sound on methodological grounds, their result showed bilinguals to be intellectually superior to their monolingual counterparts. Their study, which was conducted in Montreal, changed the face of research on bilingualism. Many studies conducted around the globe have replicated the findings of Peal and Lambert. In short, cognitive, cultural, economic, and cross-cultural communication advantages of childhood and lifelong bilingualism are many, including reversing the effects of aging (Bialystok, 2005 ; Hakuta, 1986 ). Nevertheless, the effects of bilingualism on children’s cognitive development, particularly on executive function and attention, is far from conclusive; see Klein ( 2015 ) and Bialystok ( 2015 ).

9. Bilingualism: Language Spread, Maintenance, Endangerment, and Death

Language contact and its consequences represent the core of theoretical and descriptive linguistic studies devoted to bilingualism, and onto which globalization has added a new dimension. Ironically, in the age of globalization, the spread of English and other Indo-European languages, namely, Spanish and Portuguese, has led to the rise of bilingualism induced by these languages; they also pose a threat to the linguistic diversity of the world. Researchers claim that about half the known languages of the world have already vanished in the last 500 years, and that at least half, if not more, of the 6,909 living languages will become extinct in the next century (Hale, 1992 ; Nettle & Romaine, 2000 ). Research on language maintenance, language shift, and language death addresses the questions of why and how some languages spread and others die. Phillipson and Mufwene attempt to account for language endangerment within the framework of language imperialism ( 2010 ) and language ecology ( 2001 ), respectively. Fishman ( 2013 ) examines the ways to reverse the tide of language endangerment. Skutnabb-Kangas views minority language maintenance as a human rights issue in public and educational arenas ( 1953 ).

Critical Analysis of Scholarship

Advances in our understanding of bilingualism have come a long way since the predominance of the “factional” and linguistically deficient view of bilingualism. The complexity and diverse conditions responsible for lifelong bilingualism has led to a better understanding of this phenomenon on theoretical, methodological, and analytical grounds. A paradigm shift from monolingualism and the emergence of a new, interdisciplinary approach promises new challenges and directions in the future study of bilingualism.

Issues and Conceptualization

Although bilingualism is undoubtedly a widespread global phenomenon, it is rather ironic that, for a number of reasons, including the primary objective of linguistics, multidimensional aspects of bilingualism, and misperception of bilingualism as a rare phenomenon, the study of bilingualism has posed—and continues to pose—a serious of challenges to linguistics for quite some time. This is evident from eminent linguist Roman Jacobson’s observation from more than half a century ago: “bilingualism is for me a fundamental problem of linguistics” (Chomsky, 1986 ). Similarly, Chomsky remarked that the pure idealized form of language knowledge should be the first object of study rather than the muddy water of bilingualism (Grosjean, 1989 ). Consequently, research on bilingualism has taken a backseat to monolingualism, and monolinguals have served as a benchmark to characterize and theorize bilinguals, which, in turn, led to the ill conceptualization of the bilingual person as “two monolinguals in one brain” (Dehaene, 1999 ).

Are bilinguals just a composite or sum of two monolinguals crowded in one brain? A large body of research devoted to the bilingualism and intelligence debate either implicitly or explicitly subscribed to the “two monolinguals in one brain” conception. This set the stage for the “linguistic deficiency hypothesis” about bilingual children and adults on one hand and the limited linguistic capacity of the brain on the other. When looking from the lens of monolingualism, a “factional view” (Bhatia & Ritchie, 2016 ; Nicol, 2001 ), or even distorted view, of bilingualism emerged that portrayed bilinguals as semilinguals with a lack of proficiency not just in one but two languages. Although still in its infant stage, from recent research on bilingualism, a more accurate or holistic view of a bilingual and multilingual person has begun to emerge in 1990s, namely, just as an individual bilingual does not constitute two monolinguals in one brain, a multilingual is not merely a byproduct of bilingualism alone or vice versa. Similarly, the notion that brain capacity is ideally suited for one language is a myth. Additionally and interestingly, no two bilinguals behave the same way all the time since they are not a clone of each other.

Bilingualism, unlike monolingualism, exhibits complex individual, social, political, psychological, and educational dimensions in addition to involving a complex interaction of two or more languages in terms of coexistence, competition, and cooperation of two linguistic systems. Additionally, although bilingualism is a lifelong process, the language development among bilinguals is not merely a linear process; there are turns and twists on the way to becoming bilingual, trilingual, and multilingual. The path to trilingualism is even more complex than growing up with two languages (Bhatia & Ritchie, 2016 ).

The role of sociolinguistic factors in language learning; language use (creativity); language maintenance; and language shift, particularly in trilingual language acquisition and use, opens new challenging areas of future research. The main challenge for theoreticians and practitioners is how to come to grips with various facets of the bilingual brain ranging from language contact, bilingual language interaction, to language modes of the bilingual mind/brain on one hand and methodological issues on the other.

Despite a number of studies on the Critical Period Hypothesis, and other competing hypotheses of bilingual language acquisition, future research in cognitive aptitude, age, and multiple language effects with the lens of interdisciplinary debatable findings and methodologies continues to pose new challenges and promises to the field of bilingualism (Long, 2016 ).

Further Reading

• Auer, P. , & Wei, L. (Eds.). (2007). Handbook of multilingualism and multilingual communication . Berlin: Mouton de Gruyter.
• Bhatia, T. , & Ritchie, W. (2004/2006). The handbook of bilingualism . Oxford: Wiley-Blackwell.
• Bhatia, T. , & Ritchie, W. (2013). The handbook of bilingualism and multilingualism . Oxford: Wiley-Blackwell.
• Ferreira, A. , & Schwieter, J. W. (Eds.). (2015). Psycholinguistic and cognitive inquiries into translation and interpreting . Amsterdam: Benjamins.
• Heredia, R. , & Cieś licka, A. (Eds.). (2015). Bilingual figurative language processing . New York: Cambridge University Press.
• Schwieter, J. W. (Ed.). (2015). The Cambridge handbook of bilingual processing . Cambridge, U.K.: Cambridge University Press.

Foundational Works

• Bialystok, E. , & Hakuta, K. (1994). In other words: The science and psychology of second language acquisition . New York: Basic Books.
• Cummins, J. (2000). Language, power and pedagogy: Bilingual children in the cross-fire . Clevedon, U.K.: Multilingual Matters.
• Edwards, J. R. (1994). Multilingualism . London: Routledge.
• Grosjean, F. (2008). Studying bilinguals . Oxford: Oxford University Press.
• Haugen, E. (1953). The Norwegian language in America: A study in bilingual behavior . Philadelphia: University of Pennsylvania Press.
• Mackey, W. F. (1967). Bilingualism as a world problem/Le bilinguïsme: Phenomène mondial . Montreal, QC: Harvest House.
• Romaine, S. (1995). Bilingualism (2d ed.). Oxford: Blackwell.
• Weinreich, U. (1953). Languages in contact: Findings and problems . The Hague, The Netherlands: Mouton.

Encyclopedias

• Baker, C. , & Jones, S. (Eds.). (1998). Encyclopedia of bilingualism and bilingual education . Clevedon, U.K.: Multilingual Matters.
• Byram, M. (2000). Routledge encyclopedia of language teaching and learning . London: Routledge.
• Hogen, P. (2011). The Cambridge encyclopedia of languages and linguistics . Cambridge, U.K.: Cambridge University Press.
• Bilingualism: Language and Cognition . Cambridge University Press, Cambridge, U.K.
• Journal of Multilingual and Multicultural Development . Multilingual Matters, Clevendon, U.K.
• International Journal of Bilingualism: Cross-Disciplinary and Cross-Linguistic Studies of Language Behavior . Kingston Press, London.
• International Journal of Bilingual Education and Bilingualism . Multilingual Matters, Clevendon, U.K.
• Multilingualism and Second Language Acquisition . Brill Research Perspectives, Boston.
• Altarriba, K. , & Moirier, R. (2004/2006). Bilingualism: Language, emotions and mental health. In T. Bhatia & W. Ritchie (Eds.), The handbook of bilingualism (pp. 250–280). Oxford: Blackwell.
• Annamalai, E. (2001). Managing multilingualism in India: Political and linguistic manifestations . New Delhi: SAGE.
• Baker, C. , & Jones, S. (1998). Encyclopedia of bilingualism and bilingual education . Clevedon, U.K.: Multilingual Matters.
• Bhatia, T. (2016). South Asian languages in Diaspora. In H. Hock , E. Bashir , & K. V. Subbarao (Eds.). The South Asia volume for the new series world of linguistics (pp. 673–679). Berlin: de Gruyter Mouton.
• Bhatia, T. K. (2011). The multilingual mind, optimization theory and Hinglish. In R. Kothari & R. Snell (Eds.), Chutneyfying English: The phenomenon of Hinglish (pp. 37–52). New Delhi: Penguin.
• Bhatia, T. , & Ritchie, W. (1995). The bilingual child: Some issues and perspectives. In W. Ritchie & T. Bhatia (Eds.), Handbook of child language acquisition (pp. 569–643). San Diego, CA: Academic Press.
• Bhatia, T. , & Ritchie, W. (Eds.). (2008). The bilingual mind and linguistic creativity. Journal of Creative Communication , 3 (1), 5–21.
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Bilingualism Comes Naturally to Our Brains

The brain uses a shared mechanism for combining words from a single language and for combining words from two different languages, indicating that language switching is natural for those who are bilingual.

The brain uses a shared mechanism for combining words from a single language and for combining words from two different languages, a team of neuroscientists has discovered. Its findings indicate that language switching is natural for those who are bilingual because the brain has a mechanism that does not detect that the language has switched, allowing for a seamless transition in comprehending more than one language at once.

“Our brains are capable of engaging in multiple languages,” explains Sarah Phillips, a New York University doctoral candidate and the lead author of the paper, which appears in the journal eNeuro. “Languages may differ in what sounds they use and how they organize words to form sentences. However, all languages involve the process of combining words to express complex thoughts.”

“Bilinguals show a fascinating version of this process--their brains readily combine words from different languages together, much like when combining words from the same language,” adds Liina Pylkkänen, a professor in NYU’s Department of Linguistics and Department of Psychology and the senior author of the paper.

An estimated 60 million in the U.S. use two or more languages, according to the U.S. Census . However, despite the widespread nature of bi- and multilingualism, domestically and globally, the neurological mechanisms used to understand and produce more than one language are not well understood. 

This terrain is an intriguing one; bilinguals often mix their two languages together as they converse with one another, raising questions about how the brain functions in such exchanges.

To better understand these processes, Phillips and Pylkkänen, who is also part of the NYU Abu Dhabi Institute, explored whether bilinguals interpret these mixed-language expressions using the same mechanisms as when comprehending single-language expressions or, alternatively, if understanding mixed-language expressions engages the brain in a unique way.

To test this, the scientists measured the neural activity of Korean/English bilinguals. 

Here, the study’s subjects viewed a series of word combinations and pictures on a computer screen. They then had to indicate whether or not the picture matched the preceding words. The words either formed a two-word sentence or were simply a pair of verbs that did not combine with each other into a meaningful phrase (e.g., “icicles melt” vs. “jump melt”). In some instances, the two words came from a single language (English or Korean) while in others both languages were used, with the latter mimicking mixed-language conversations.

In order to measure the study subjects’ brain activity during these experiments, the researchers deployed magnetoencephalography (MEG), a technique that maps neural activity by recording magnetic fields generated by the electrical currents produced by our brains.

The recordings showed that Korean/English bilinguals, in interpreting mixed-language expressions, used the same neural mechanism as they did while interpreting single-language expressions. 

Specifically, the brain’s left anterior temporal lobe, a brain region well-studied for its role in combining the meanings of multiple words, was insensitive to whether the words it received were from the same language or from different languages. This region, then, proceeded to combine words into more complex meanings so long as the meanings of the two words combined together into a more complex meaning. 

These findings suggest that language switching is natural for bilinguals because the brain has a combinatory mechanism that does not “see” that the language has switched.

“Earlier studies have examined how our brains can interpret an infinite number of expressions within a single language,”  observes Phillips. “This research shows that bilingual brains can, with striking ease, interpret complex expressions containing words from different languages.”

Phillips discusses research on bilingual speakers in this NYU-produced video (credit: New York University, courtesy of Kate Lord).

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Bilingual education for young children: review of the effects and consequences

Ellen bialystok.

Department of Psychology, York University, Toronto, ON, Canada

Bilingual education has been an educational option in many countries for over 50 years but it remains controversial, especially in terms of its appropriateness for all children. The present review examines research evaluating the outcomes of bilingual education for language and literacy levels, academic achievement, and suitability for children with special challenges. The focus is on early education and the emphasis is on American contexts. Special attention is paid to factors such as socioeconomic status that are often confounded with the outcomes of bilingual education. The conclusion is that there is no evidence for harmful effects of bilingual education and much evidence for net benefits in many domains.

In the US, bilingual education has been a controversial topic almost since the founding of the nation, and from the beginning, the discussions were imbued with political rhetoric (for reviews see Nieto 2009 ; Ovando 2003 ). The Bilingual Education Act of 1968 recognized the situation of minority children with limited proficiency in English and created funding for programs that would assist these children to succeed in American schools and develop their proficiency in both English and their home language. The act was largely focused on Spanish speakers, but subsequent groups, such as Chinese speakers, brought about amendments to the act to expand its scope ( Lau vs. Nichols, 1974 ). Other countries have had a different experience with bilingual education and a different set of political and social associations with these programs. A prime example is Canada, where the social, demographic, and political situations were different from those in the US. Although Canada is officially a bilingual country, there is not a single language that defines most bilinguals as there is in the US, because the majority of bilinguals in Canada speak one of the official languages (English or French) and a heritage language. Surprisingly, few citizens are actually proficient in both official languages. In the 2011 census, about 17% of respondents stated they could conduct a conversation in both English and French, a considerable increase from the estimate of 12% who could achieve this in 1961 ( Lepage and Corbeil 2013 ), although still below what would be expected in a bilingual society. One factor that may be responsible for the growth in French-English bilingualism over the 50-year period is the impact in the past generation of popular French immersion programs in which children who would otherwise have had little exposure to French became very proficient and in many cases, fully bilingual.

In Europe, attitudes to languages, educational systems, and bilingualism in general, to name a few factors, are very different from those in North America. Garcia (2011) makes a strong case for the widespread appropriateness of bilingual education globally, but the context in which education takes place is crucial; there is no universal prescription for bilingual education and no universal outcomes. As Baker (2011) points out, the perspective on bilingual education depends largely on the point of view, and studies conducted in one context may have little relevance for bilingual education in another context. Therefore, this review will focus primarily on North American contexts and address some of the central issues regarding the efficacy of bilingual education for that region, in particular for the US.

Finally, the review will focus on the early school years because they are the foundation for academic outcomes. Education is a long-term process and results continue to influence outcomes throughout life. However, the early years are crucial for establishing basic skills and attitudes toward education, so the examination of bilingual education in the present review will focus on the first three years of schooling. To summarize, the review is restricted in that it selectively reviews studies whose empirical properties are considered sufficiently reliable to form conclusions, with a focus on primary education in the context in the US, and addressing specific questions, namely, language outcomes, cognitive outcomes, and generalized appropriateness of the programs.

Bilingual education is an umbrella terms that encompasses a range of education programs that have been designed for an even wider range of children and a host of special circumstances. Essentially, bilingual education refers to any school program in which more than one language is used in the curriculum to teach non-language academic subject matter or the language of schooling does not match the language of the home or community, but the reasons for incorporating the languages, the specific languages chosen, the structure of the program, and the relation between the school languages and the community vary widely and influence educational outcomes. Over-riding all this is the distinction between ‘bilingual education’ and the ‘education of bilingual children’, concepts that are importantly different from each other. Consider the following two definitions for bilingual education. Genesee (2004 , 548) defined bilingual education as ‘education that aims to promote bilingual (or multilingual) competence by using both (or all) languages as media of instruction for significant portions of the academic curriculum’. In contrast, Rossell and Baker (1996 , 7) defined bilingual education as ‘teaching non-English-speaking students to read and write in their native tongue, teaching them content in their native tongue, and gradually transitioning them to English over a period of several years’. Clearly these definitions are describing different situations and carry different goals.

This distinction between bilingual education and the education of bilingual children is part of the historical difference between the development of bilingual education in the US and elsewhere. For bilingual education of minority language students in the US, the motivation was to create an educational program for children who were at-risk of academic failure because of low proficiency in English, the language of schooling, by engaging them in the education process through the use of their home language (e.g. including Spanish in the education of Hispanic children). The success of these programs was judged primarily by proficiency in English (the majority language), with the main criterion being English language literacy. For bilingual education in Canada, in contrast, the motivation was to offer an educational alternative designed to make majority language children (i.e. English speakers) bilingual. Thus, success of these programs was judged by the extent to which children mastered the minority language while maintaining proficiency in the majority language. Similar immersion programs were developed for children to gain proficiency in both national (e.g. children of Finnish immigrants in Sweden, Troike 1978 ) and heritage languages (e.g. Hawaiian programs in the US, McCarty and Watahomigie 1998 ; Navajo programs in the US, Rosier and Holm 1980 ; Maori programs in New Zealand; Durie 1998 ; May and Hill 2005 ). All these programs fall under the general rubric of bilingual education but are importantly different from each other. A more complete range of the diversity of bilingual education programs is described by Fishman (1976) and more recently by Mehisto and Genesee (2015) .

In spite of substantial differences between them, the two goals of educating bilingual children and creating programs to make children bilingual are interrelated. In the US, there is large overlap between them because the largest number of bilingual education programs was developed to educate bilingual or limited English proficient (EP) students, primarily Spanish-speaking, who were otherwise at-risk for school failure. The present review will focus on bilingual education in general and not on the specific issues involved in the education of this particular group of children (for a detailed discussion of this issue, see August and Shanahan 2006 ). Ultimately, it is important to know if education through two languages is viable, if young children can learn in this kind of an environment, and if the outcomes of these programs meet the needs of all children. The present paper reviews evidence relevant for those judgments.

Development of language and literacy in bilingual education

Evaluation of the effectiveness of bilingual education on language and literacy outcomes requires well-controlled research. The clearest evidence for the unique contribution of bilingual education programs to these outcomes would come from randomized control trials, but such a design is almost impossible to achieve (but see Genesee and Lindholm-Leary 2012 , for discussion). The closest design to this methodological ideal is in studies that investigate bilingual education programs for which spaces are allocated by lottery because of over-demand so that comparisons can be made between children who were admitted to the program and those who were not. Children in this latter group generally enter regular classrooms and may remain on a waiting list. Even here, however, there is the possibility of bias in terms of who enters the lottery. The results of the few studies that have had the opportunity to compare these populations (e.g. Barnett et al. 2007 ) are largely consistent with the majority of the literature in which children in bilingual or single language programs are compared on critical outcome measures.

The primary goal of early schooling is to establish the foundational skills upon which children will build their educational futures. The most important of these abilities are language and literacy competence. Not surprisingly, therefore, the majority of research that has evaluated bilingual education programs has focused on children’s development of these crucial linguistic abilities. The research is complicated because the type of education program is only one of many factors that shape these emerging abilities so clear evidence for the role of the education program as distinct from other sources of variance in the child’s background requires carefully controlled designs. For example, children who are Hispanic but are native speakers of English have education outcomes in terms of dropout rates and academic failure that are similar to Hispanic children who are Spanish-speaking, ruling out English proficiency as the explanation ( Forum for Education and Democracy 2008 ). Just as English proficiency alone cannot explain school outcomes, neither can the educational program.

In part for this reason, conclusions regarding the development of language and literacy through bilingual education in the US is complicated by the confounding of ethnicity and social class with Spanish proficiency and bilingualism (for discussion see Francis, Lesaux, and August 2006 ). Nonetheless, two studies by Lindholm-Leary and colleagues have provided reasonably clear results on these issues. In one study, Lindholm-Leary and Block (2010) assessed the English and mathematics achievement of 659 Hispanic students attending either mainstream English or various types of bilingual programs in California. In the bilingual schools, the proportion of instruction shifted from predominantly Spanish to predominantly English over the period from kindergarten to fourth grade. Students were classified as EP or English Language Learner (ELL) prior to the study. The main result was that standard scores on the English proficiency test were higher for both ELL and EP students who were in the bilingual programs than they were for children in the mainstream English programs. Similar results were found for scores on the mathematics test. Overall, students in the dual language program in this low socioeconomic status (SES) community achieved at least as well and in some cases better in both English and mathematics than did comparable students in a program in which all instruction was in English. Students in the bilingual programs also made more rapid progress across the grades in these tests than did students in the English program and, therefore, were more advanced in their trajectory to close the achievement gap with statewide norms for these tests.

In a similar study that included children in kindergarten through second grade, Lindholm-Leary (2014) assessed 283 low SES Hispanic children in either English or bilingual programs. Children entering the English kindergarten programs had higher language scores than those entering the bilingual programs, but these differences disappeared within one or two years and then reversed, with children in the bilingual program outperforming the English-only instruction group in both English and Spanish test scores by the end of second grade. Not surprisingly, children in the English program showed significant loss of Spanish proficiency, making them in fact less bilingual, a topic that will be discussed below.

Barnett et al. (2007) compared performance of low SES preschool children (3 and 4 years old) in bilingual or English-only programs, but importantly, children were assigned to these programs by lottery, thereby controlling to some extent for pre-existing differences among the children or their families. The programs were in a school district in which 76% of the children qualified for free or reduced-price lunch. The outcome measures were largely experimental tasks that assessed phonological awareness and language knowledge (primarily vocabulary), but the results were consistent with those reported in other studies. Specifically, children in both programs made comparable progress in skill development in English, but children in the bilingual program also developed these skills in Spanish, indicating that dual language instruction did not impede development of English, the L2.

In these examples, bilingual instruction had long-term benefits for children’s language and literacy proficiency in both languages. In a review and meta-analysis of this literature, Francis, Lesaux, and August (2006) concluded that ‘bilingual education has a positive effect on English reading outcomes that are small to moderate in size’ (392). Thus, overall, bilingual education for Hispanic children in the US leads to English outcomes that are equivalent to those found for children in mainstream English programs, with better outcomes for Spanish.

These results are broadly consistent with those found for bilingual education programs serving other communities, with other languages, in other countries, where students are more likely to belong to majority language groups than minority language, as in the US. Thus, the outcomes obtained with children at risk for educational failure produce patterns of results similar to those found for children with entirely different linguistic and demographic backgrounds. The most studied of these programs is Canadian French immersion in which Anglophone children in Canada are educated through French. Results of studies over the past 50 years have shown that English outcomes are equivalent to or better than those found for children in English programs (even though most instruction is in French in the primary grades) and French outcomes are moderate to high, although below levels found for native-speaking French children ( Genesee 1983 , 2004 ; Hermanto, Moreno, and Bialystok 2012 ; Swain and Lapkin 1982 ).

Three further examples with similar results come from bilingual programs operating in Italian and English, Mandarin and English, and Hebrew and Russian. Assessment of the Italian-English program was a small-scale study in which 60 children attending this program in California were evaluated from first through third grades for language and literacy ability in English and Italian ( Montanari 2013 ). Results showed that these children developed strong literacy skills in both Italian and English by first grade, even though instruction was exclusively in Italian. The second program, also implemented in California, provided instruction through Mandarin beginning in kindergarten to children who either had Mandarin exposure at home or were only English speaking ( Padilla et al. 2013 ). Like the Italian-English program, this was a small-scale study. The results showed that all children gained proficiency in both English and Mandarin and importantly achieved at least equivalent and sometimes greater than state levels on standardized tests of English, math, and science in spite of being educated through Mandarin. Finally, two studies investigated language and literacy development in Russian-Hebrew bilingual 4-year-olds who were attending either bilingual Hebrew-Russian or Hebrew schools in Israel, where Hebrew is the majority language. Again, the results showed that children in the bilingual programs developed language proficiency ( Schwartz 2013 ) and narrative skills ( Schwartz and Shaul 2013 ) in Hebrew, the majority language, at least as well as did children in the Hebrew only programs and at the same time maintained higher levels of Russian. Across all these studies, therefore, the majority language of the community was mastered whether or not it was the primary language of instruction, but the minority language required environmental support to reach high proficiency levels.

The studies that compared English-only and bilingual education in Hispanic children were generally conducted with low SES populations, but that is not the case for the non-Spanish programs: children in the Italian-English program were described as ‘middle class’; children in the Mandarin-English program were described as ‘upper middle class’; and children in the Hebrew-Russian program were described as ‘mid-level socioeconomic’. Thus, even though none of the students was at-risk in the manner generally understood for Hispanic children in Spanish-English bilingual programs, the patterns of language and literacy outcomes were similar, even if the absolute levels of achievement were different. Therefore, there is no evidence that education through two languages impedes progress in the development of language and literacy skills in the majority language and has the added benefit of developing and sustaining these skills in the minority language. This generalization about positive outcomes is confirmed by a study in which at-risk low performing children attending bilingual education or majority language English-only programs were compared for their English language and literacy performance ( Lopez and Tashakkori 2004 ). There was no evidence of additional burden on the development of English skills for children in the bilingual program.

Other academic and cognitive achievements

However important language and literacy are for children’s development, they are not the only outcomes that need to be considered in evaluating educational options for children. The impact of education through a weak or non-proficient language on children’s academic success has long been a concern. Dire warnings about harmful effects of these programs were expressed by Macnamara (1967) in his evaluation of children attending an Irish immersion program in Ireland. He reported that children in the Irish program performed more poorly in mathematics than did children in regular English programs, but he neglected to point out that the differences were found only in mathematics ‘word’ problems and not in mathematical operations. Unsurprisingly, children’s knowledge of Irish at that point was weak and interfered with their comprehension of the test questions; in tests of arithmetic calculations, there were no differences between groups. These challenges have been known for a long time (e.g. Cummins and Macnamara 1977 ) but the research remained influential. More recent research demonstrates that even simple arithmetic calculation is faster and easier in the language in which it was taught ( Spelke and Tsivkin 2001 ) and engages different parts of the brain than when the same calculations are performed in the non-school language ( Mondt et al. 2011 ), but the Irish proficiency of the children in Macnamara’s (1967) study may have been too weak to show this effect.

Other studies have generally found no academic cost for children studying in a bilingual program. In the Mandarin-English bilingual education program described above ( Padilla et al. 2013 ), for example, children in the dual language immersion and the English programs performed equivalently on standardized tests of mathematics until third grade, but immersion children began outperforming non-immersion children in fourth grade. Thus, these program effects sometimes take time to demonstrate. For tests of science achievement, there were no differences between children in the two programs.

There is evidence that bilingualism alone, aside from bilingual education, may be beneficial for aspects of academic achievement. Han (2012) conducted a longitudinal study in the US of a national cohort of over 16,000 children in kindergarten and followed their academic progress until fifth grade. Because of national education policies requiring standardized testing on English literacy and math scores, large data bases are available for such investigations. In the study by Han (2012) , the children included in the analyses were Hispanic, Asian, or non-Hispanic native-born White and outcome variables were results on standardized reading and math achievement scores. Although the analyses did not explicitly control for the effect of education program, the quality of education was defined in terms of the resources and interventions for English support available in the school program, quality of the teachers, and other such factors and included in the analyses. The results were based on a complex classification of children according to their language abilities. Most relevant is a group called ‘mixed bilingual’, referring to children who spoke a non-English language at home to a high degree of fluency. Although these children entered kindergarten with limited English proficiency and obtained initial scores on both English and math tests that were lower than native English-speaking children, they fully closed the math gap by fifth grade, an achievement that the Han attributes to bilingualism. Nonetheless, English scores still lagged by fifth grade. The focus of the analyses were on quality of school programs, availability of resources, and quality of school personnel, all of which contributed significantly to children’s success. The study was not designed to evaluate the effectiveness of bilingual education but the results are consistent with the conclusion that children’s bilingualism can be a positive factor in school achievement.

Much of this research has focused on children in low SES environments, but Marian, Shook, and Schroeder (2013) extended the question to investigate whether these results would be similar for Spanish-speaking low SES children and monolingual English-speaking middle-class children who were in Spanish-English bilingual programs and were instructed through Spanish from kindergarten. The numbers of children in each of the relevant groups defined by language and social background, grade, and education program were vastly different (ranging from 6 to 624), so non-parametric analyses were used and results need to be interpreted cautiously. The analyses of children’s performance on standardized tests of reading and mathematics showed better outcomes for children in bilingual programs than monolingual programs for both minority Spanish and majority English-speaking children, although there were differences in the size and timing of these effects for children from the two language backgrounds. Thus, all children profited from the bilingual education program, although not surprisingly their progress depended as well on other factors known to affect education outcomes.

One explanation that Marian and colleagues offer for the better mathematics outcomes for children in the bilingual programs is that the bilingualism achieved in these programs led to higher levels of executive function and that better executive function was the mechanism for the improvement in math performance. Several studies of young children in the early grades have demonstrated a direct relationship between children’s executive functioning and mathematics achievement ( Blair and Razza 2007 ; Bull, Espy, and Wiebe 2008 ) and a large body of research has established that bilingualism promotes the development of executive function in young children (see Barac et al. 2014 for review; Adesope et al. 2010 for meta-analysis). Importantly, children’s level of executive functioning predicts academic success ( Best, Miller, and Naglieri 2011 ; McClelland, Morrison, and Holmes 2000 ), and academic success predicts long-term health and well-being ( Duncan, Ziol-Guest, and Kalil 2010 ). Therefore, bilingual education may have a serendipitous effect in that it not only promotes bilingualism but also enhances a crucial aspect of cognitive performance.

There is a large and growing literature investigating the relation between bilingualism and executive functioning in young children, but three studies are particularly relevant. The first study is interesting because the results were unexpected. Mezzacappa (2004) used the children’s Attention Network Task ( Fan et al. 2002 ) to assess executive functioning in 6-year-old children who varied in SES (middle-class or low) and ethnicity (White, African-American, or Hispanic). In addition to expected effects of SES, he found that Hispanic children outperformed the other groups, particularly on the most difficult condition. Although he did not collect information about children’s language proficiency or level of bilingualism, he noted that 69% of the Hispanic children spoke Spanish at home, making them at least somewhat bilingual. Mezzacappa proposed that this bilingualism was responsible for the superior executive function performance by children in that group.

The second study was a relatively small-scale study that examined children from low SES communities in which about 90% of children received free or reduced-price lunch. Esposito and Baker-Ward (2013) administered two executive function tasks to children in kindergarten, second grade and fourth grade who were in a bilingual education or English-only program. Their results showed that children in second and fourth grades in the bilingual program outperformed children in the English program on the trail-making task, an executive function task that has previously been shown to be performed better by bilingual than monolingual 8-year-olds ( Bialystok 2010 ). There were no differences between children in the two kindergarten programs, but all these children found the task to be difficult. Because of the small sample size, the results need to be considered more suggestive than definitive, but they point to the possibility that even limited exposure to bilingual education improves children’s executive function.

Another small-scale study conducted with a population of middle-class children from kindergarten through second grade produced somewhat different results. Kaushanskaya, Gross, and Buac (2014) examined the effects of classroom bilingualism on executive functioning as measured by task shifting as well as measures of verbal memory and word learning. For task switching, they used the Dimensional Change Card Sorting Task ( Frye, Zelazo, and Palfai 1995 ), a task previously found to be performed better by bilingual than monolingual preschool children ( Bialystok 1999 ). There were no performance differences between children in the two programs on the executive function shifting task, but the task was arguably too easy for the children since it is typically used with younger children, or on a test of verbal short-term memory. However, tests of verbal working memory and word learning were performed better by the children in the bilingual education program.

In these three examples, children who were assigned to groups either because of ethnicity ( Mezzacappa 2004 ) or education program ( Esposito and Baker-Ward 2013 ; Kaushanskaya, Gross, and Buac 2014 ) were compared to controls for their performance on executive function tasks. A different approach is to use exposure to bilingual education as a scaled variable to determine if it is associated with executive function performance and thereby avoid between-groups comparisons. Two studies by Bialystok and Barac (2012) investigated the relation between the amount of time young children had spent in an immersion program and performance on executive function tasks. Children from monolingual English-speaking homes who were attending schools in which instruction was either in Hebrew (Study 1) or French (Study 2) were administered executive function and metalinguistic tasks. The tasks were different in both studies, but the results were the same: performance on the metalinguistic task was related to children’s verbal ability and intelligence but performance on the executive function task was related to the length of time children had spent in the bilingual program and their degree of bilingualism. Similar results were reported in two studies by Nicolay and Poncelet (2013 , 2015 ) showing better performance on executive function tasks for children in French immersion programs. In these studies, children were followed longitudinally, ruling out initial differences in ability. Thus, the results show that children’s level of executive function performance is related to their degree of bilingualism and experience with bilingual education.

Is bilingual education for everyone?

There have always been questions about whether bilingual education programs were appropriate for all children or whether they were an exclusive option best suited for high-achieving students with strong family support (see review and discussion in Cummins and Swain 1986 ). Equally, some have argued that bilingualism itself is difficult and should be reserved as a ‘privilege’ for children who face no additional burdens from linguistic or other cognitive challenges, a position strongly disputed by Kohnert (2007) . Unsurprisingly, the answer is not simple, but the evidence that exists supports Kohnert’s view that bilingualism adds no further cost to children’s achievement regardless of their initial levels of language and cognitive ability.

Consider first the role of intelligence, a variable on which all children differ. In one of the first studies on this issue, Genesee (1976) examined the role of IQ as measured by a standardized test on the development of French second-language abilities for children who were learning French either through immersion or foreign language instruction in school. The main result was that IQ was related to reading ability and language use for all children, but there was no association between IQ and overall communication ability; children at all levels of intelligence communicated with similar effectiveness. Importantly, there were no interactions with the type of program in which children were learning French: low IQ children in the immersion and foreign language program performed similarly to each other on all language and cognitive measures, in both cases performing more poorly than children with higher IQ scores in both programs. Thus, there was no evidence of any negative effect of participation in an immersion program for children whose measured intelligence was below average.

More serious than low IQ, however, is the possible role that a learning disability, such as specific language impairment (SLI), might play in children’s response to bilingual education. The limited evidence for this question is similar to that found for IQ, namely, that the deficit associated with SLI is not further exacerbated by bilingual education and has the additional consequence of imparting at least some measure of proficiency in another language. Few studies have investigated this question in the context of bilingual education, perhaps because children with language impairment are widely discouraged from attending bilingual education programs, but an early study by Bruck (1982) assessed language and cognitive outcomes for children in kindergarten and first grade in French immersion programs, some of whom had been diagnosed with language impairment. These were Anglophone children being educated through French, and linguistic measures for both French and English were included. The crucial comparison was the progress found for language-impaired children in the French immersion program and similar children in a mainstream English instruction program. There were no significant differences between these groups. Even though these children struggled, they did not struggle more than they would if they were in the bilingual program. This issue of selecting the appropriate comparison is central to the debate. Trites (1978) , for example, argued against placing children with learning disabilities in French immersion programs, but his comparison was based on children without learning disabilities in those programs rather than children with learning disabilities in monolingual English programs.

Aside from the role of bilingual education in children’s language development, it is difficult to compare skills in the two languages for children with SLI because the areas of linguistic difficulty associated with this disorder vary across languages ( Kohnert, Windsor, and Ebert 2009 ). With this caveat in mind, a few studies have examined the effect of SLI on language development for children who grow up bilingually. Korkman et al. (2012) compared monolingual Swedish speakers and Swedish-Finnish bilingual children who were 5–7 years old on a range of language assessments in Swedish. About half of the children in each language group were typically developing and half had been diagnosed with SLI. As expected, children with SLI performed more poorly than typically developing children on these linguistic measures, an outcome required by definition, but there was no added burden from bilingualism and no interaction of bilingualism and language impairment. Bilingual children also obtained lower scores on some vocabulary measures, but this occurred equally for bilingual children in the typically developing and SLI groups and is consistent with large-scale studies comparing the vocabulary of monolingual and bilingual children ( Bialystok et al. 2010 ).

Paradis et al. (2003) took a different approach to investigating syntactic proficiency in children with SLI. Rather than comparing children with SLI to typically developing children, they compared three groups of 7-year-old children, all of whom had been diagnosed with SLI: monolingual English speakers, monolingual French speakers, and English-French bilinguals. The sample was small and consisted of only 8 bilingual children, 21 English monolingual children, and 10 French monolingual children, so data were analyzed with non-parametric tests and results must be interpreted cautiously. The results showed no significant differences between the three groups of children in their mastery of morphosyntax; in other words, no additional delay to language acquisition could be attributed to bilingualism for children with SLI.

The most salient risk factor generally considered in this literature is not individual differences in children’s ability to become bilingual but rather low SES, a situation that applies to many bilingual Hispanic children in the US. Although it was discussed above in the context of testing outcomes of bilingual education, the issue is sufficiently important to warrant further consideration.

The main concern for Hispanic children from Spanish-speaking homes in the US is whether they will acquire adequate levels of English language proficiency and literacy to function in school and beyond. Although there is some controversy over this question, the majority of studies have shown improved outcomes with bilingual education ( Genesee and Lindholm-Leary 2012 ). This conclusion is supported by two major reviews and meta-analyses conducted first by Willig (1985) and then by Rolstad, Mahoney, and Glass (2005) for papers published after the Willig review. In a later review and meta-analysis, Francis, Lesaux, and August (2006) came to a broader and more emphatic conclusion: ‘there is no indication that bilingual instruction impedes academic achievement in either the native language or English, whether for language-minority students, students receiving heritage language instruction, or those enrolled in French immersion programs’ (397). The most persuasive evidence on this point comes from the large-scale longitudinal study and review conducted by Collier and Thomas (2004) that included every variety of bilingual education; the authors decide unequivocally for the superiority of bilingual education in developing the skills and knowledge of Hispanic and other at-risk children.

Contrary to this conclusion, Rossell and Baker (1996) argued that the effectiveness of bilingual education is inconclusive. As stated earlier, Rossell and Baker defined bilingual education narrowly and considered only programs that provided instruction through the first language for limited EP children, in other words, Spanish-speaking children in the US (although curiously they included some studies of Canadian French immersion in their analyses). However, this is only one of the many incarnations of bilingual education so while an evaluation of its effectiveness is important, that evaluation does not necessarily generalize to the broader concept, a point that Rossell and Baker acknowledge. Their review began with a list of 300 studies and then excluded 228 of them for a variety of methodological reasons, so the final sample of 72 studies that entered the meta-analysis may not be representative of this literature. However, Greene (1997) conducted a follow-up study from the same database using different inclusion criteria and reported that a meta-analysis found positive outcomes for bilingual education. The decision about inclusion or exclusion of specific studies is obviously crucial to the outcome; Rossell and Baker acknowledge that Willig’s (1985) positive conclusion can be traced to her choices on this important decision. However, it is impossible to adjudicate between these two conclusions regarding whether bilingual education is the most effective way to promote English language skills in limited English proficiency children ( Willig 1985 ) or not ( Rossell and Baker 1996 ) because the conclusions were based on different evidence. Yet, whether or not there are advantages, the evidence is clear that there is no cost to the development of English language skills in bilingual programs. What is completely uncontroversial is that bilingual education additionally maintains and develops Spanish skills in these children, an outcome that Rossell and Baker note but dismiss as irrelevant.

A different way of considering the impact of bilingual education on school outcomes for low SES Hispanic children in the US is to use data on the reclassification of children from ELL to EP, a decision made on the basis of English language and literacy test scores. In that sense, reclassification is an indication that adequate levels of English proficiency have been achieved. Lindholm-Leary and Block (2010) note that the probability of these children being designated as EP after 10 years of essentially mainstream English classrooms is only 40%, so the standard is low. However, Umansky and Reardon (2014) compared this reclassification rate for Hispanic students enrolled in either bilingual or English-only classrooms and found that these rates were lower in elementary school for children in bilingual programs than in English classrooms, but that the pattern reversed by the end of high school at which time children in bilingual programs had an overall higher rate of reclassification and better academic outcomes. As with some of the studies based on test scores, English proficiency takes several years to develop, but according to the reclassification data, it developed sooner in the bilingual programs.

In a review of studies that have examined the effect of various risk factors on children’s response to bilingual education, Genesee and Fortune (2014) found no case in which the bilingual education program contributed to lower academic outcomes for these children than for similar children in monolingual programs. Children with language disability, for example, will always find language tasks to be difficult; the important outcome of this research is that they do not find such tasks to be any more difficult in two languages than they are in one.

Evaluation of bilingual education for young children

In most evaluation research for educational programs, the conclusion tends to converge on a binary answer in which the program is considered to be either effective or not, or more or less effective than a control or alternative program. Given the complexity of bilingual education, such binary conclusions are inadequate. One reason is that independently of the quality of the program, bilingual education to some extent will almost inevitably help children to become bilingual or maintain bilingualism, an outcome that in itself is valuable but rarely considered in strict program evaluations. Some research has shown that even at early stages of bilingual education the cognitive advantages of bilingualism can be detected. Therefore, beyond the possible cognitive benefits of bilingualism described above are the intangible benefits of bilingual education such as potential to connect to extended family, increased opportunity for employment in a global economy, facilitation of travel and broadening of social spheres, and enrichment from widened horizons from language, arts, and culture. When successful, bilingual education offers a unique opportunity to impart the resources to sustain a valuable lifestyle asset. As one example, recent research has shown that lifelong bilingualism contributes to cognitive reserve and delays the onset of symptoms of dementia (reviews in Bak and Alladi 2014 ; Bialystok et al. 2016 ).

These consequences of bilingualism, however, should not bias the interpretation of the evidence regarding the educational efficacy of bilingual education. To undertake that assessment, it is necessary to return to the distinction between bilingual education and the education of bilingual children. The first is a general question about the feasibility of educating children through a language in which they may not be fully proficient; the second is a specific question about the appropriateness of this option for children whose circumstances and abilities may mitigate those educational outcomes.

Both questions can be considered in terms of two factors that permeate many of these studies: the type of outcome measured and the demographic profile of the children in the program. Regarding the first, the main distinction is whether the studies assessed language proficiency or some other cognitive or academic outcome. Most studies included an evaluation of language proficiency in the majority language (English for Hispanic children in the US, French immersion children in Canada, community language for indigenous language programs in the US and elsewhere) and some included assessments of proficiency in the minority language, which is often the language of instruction (e.g. Spanish in the US, French in Canada, Maori in New Zealand). Fewer studies examined assessments of other educational outcomes, such as mathematics, subject curricula, cognitive ability, retention rates, attitudes, or enrollment in higher education. The second factor is whether the children assessed in these studies were at risk of academic failure for any number of reasons, such as low SES, poor language proficiency, or individual difficulty from learning, language, or social challenges. This combination of factors creates four categories for which there are three possible outcomes: (a) no measurable difference between bilingual and standard programs, (b) some advantage for participation in a bilingual program, or (c) hardship for students in bilingual programs that leads to poorer outcomes than would be obtained in traditional programs. If we consider that all bilingual programs additionally support some degree of bilingualism, then the only negative outcome would be (c).

Regarding language assessments, most studies show that proficiency in the majority language is comparable for children in bilingual and mainstream classes, providing that an appropriate comparison group is used and sufficient time is allowed. Children in Canadian French immersion programs develop English language skills that are at least comparable to those of other middle-class children in English programs (and sometimes higher but there may be other factors involved because of the selectivity of French immersion, see Hutchins 2015 ), and Hispanic children in US bilingual education programs eventually develop English language skills that are comparable to those of similar Hispanic children in English programs, although it takes several years to reach that level. Proficiency in the minority language is inevitably lower than is found for a native speaker of those languages, even when it is the language of instruction, but is invariably higher than levels obtained by children in English programs who have had little exposure to that language. For language proficiency, therefore, there is no evidence of a cost to the development of either language, although it may take several years to establish desired levels.

For other subject material, outcomes depend in part on the language of testing. As Macnamara (1967) showed long ago, the extent to which a weak language is used to conduct achievement tests can make the test equally a test of language proficiency, impeding children’s demonstration of proficiency in the tested content. In many cases, studies that assess academic achievement provide inadequate information about the potential involvement of language proficiency so the test results are sometimes indeterminate. At the same time, Mondt and colleagues (2011) demonstrated that simply by teaching a subject through a particular language makes proficiency in that subject more fluent when tested in the language of schooling. Thus, there are reciprocal relationships between academic achievement and the language of school instruction, and these relationships are flexible.

The second factor is the characteristics of the children themselves. Children entering school with any learning or language disability or social disadvantage will struggle to succeed, so an evaluation of bilingual education needs to hold constant these abilities and select the appropriate comparison group. Thus, the relevant question is whether children struggle disproportionately more if they are in a bilingual education program. Here, too, the evidence seems clear: there is no additional burden for children with specific challenges in bilingual programs than in single language programs if the appropriate comparison is made. But even if there were additional effort required by bilingual education, it needs to be evaluated in terms of the potential benefits for that child – the possibility of acquiring a heritage language, the opportunity to develop at least some proficiency in another language, and the potential for attaining the cognitive benefits of bilingualism.

Bilingual education is not perfect and it is not one thing. At the same time, the quality of the research is uneven and it is difficult to determine how much weight should be assigned to contradictory outcomes. The research generally pays inadequate attention to the social context in which these complex processes play out, such as home literacy, parental education, children’s levels of language proficiency, ability of parents to support children’s education in that language, and numerous other factors. Rossell and Baker (1996) claim that the research is inconclusive, and although there is still much to be learned, the weight of evidence is firmly on the side of bilingual education. In this brief review of a small portion of bilingual education programs in different countries and aimed at educating different kinds of children, there is no evidence that it creates measurable obstacles to children’s school achievement. Some studies show no advantage of bilingual education over other programs, but those need to be interpreted in terms of the benefits of learning another language and gaining access to the cognitive advantages of bilingualism. Ultimately, a proper evaluation of bilingual education requires detailed description of the structure of the program, the quality of the teaching, and the match between children’s needs and abilities and the specific educational program being offered.

There is no single factor that can override the deep complexity of children’s development and prescribe a solution for an individual child, let alone a solution for all children. For both gifted children who are certain to excel and children who face challenges, the education program they follow, including participation in a bilingual program, may not fundamentally change their school experience. There is no credible evidence that bilingual education adds or creates burden for children, yet it is incontrovertible that it provides the advantage of learning another language and possibly the cognitive benefits of bilingualism. The over-riding conclusion from the available evidence is that bilingual education is a net benefit for all children in the early school years.

Acknowledgments

This work was supported by the US National Institutes of Health [grant number R01HD052523].

Disclosure statement

No potential conflict of interest was reported by the author.

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