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Learn Landsc. Author manuscript; available in PMC 2018 Oct 2.

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Abstract

Many children in North America and around the world grow up exposed to two languages from an early age. Parents of bilingual infants and toddlers have important questions about the costs and benefits of early bilingualism, and how to best support language acquisition in their children. Here, we separate common myths from scientific findings to answer six of parents' most common questions about early bilingual development.

Bilingualism in the Early Years: What the Science Says

Bilingual parents are vocal in their desire to raise proficient, dynamic bilingual children. They have questions, and they want answers. But there is a complicated history of positive and negative press about raising children in bilingual households, to the point where some pediatricians-even today-recommend against exposing children to two languages. Attitudes against early bilingualism are often based on myths and misinterpretations, rather than scientific findings. Here, we aim to address the most frequently asked questions about childhood bilingualism using research findings from a variety of scientific fields including developmental psychology, cognitive psychology, education, linguistics, and communication sciences and disorders. This article is intended for parents and the many people who parents turn to for advice about fostering successful bilingual development: preschool teachers, elementary teachers, pediatricians, and speech-language pathologists.

Bilingualism refers to the ability to use two languages in everyday life. Bilingualism is common and is on the rise in many parts of the world, with perhaps one in three people being bilingual or multilingual ( Wei, 2000). Contact between two languages is typical in regions of many continents, including Europe (Switzerland, Belgium), Asia (India, Philippines), Africa (Senegal, South Africa), and North America (Canada). In the United States, a large (and growing) number of bilinguals live in California, Texas, Florida, New York, Arizona, and New Mexico. In California, for example, by 2035, it is expected that over 50% of children enrolled in kindergarten will have grown up speaking a language other than English ( García, McLaughlin, Spodek, & Saracho, 1995). Similarly, in some urban areas of Canada such as Toronto, up to 50% of students have a native language other than English ( Canadian Council on Learning, 2008).

Despite the prevalence of bilingualism, surprisingly little research has been conducted on the topic, particularly on the foundations of bilingual language learning in infants and toddlers. The science of bilingualism is a young field, and definitive answers to many questions are not yet available. Furthermore, other questions are impossible to answer due to vast differences across families, communities, and cultures. But with an accumulation of research studies over the last few decades, we are now equipped to partially answer some of parents' most pressing questions about early bilingualism.

There are few venues for communicating scientific findings about early bilingualism to the public, and our goal is to distill bilingual and developmental science into practical, accessible information. We are researchers who study bilingual infants and children, and as such, we interact with bilingual families regularly. When we give community talks to preschools and nonprofit organizations about language development in early childhood, the question-and-answer period is invariably dominated by questions about early bilingualism. The consistency in questions is astonishing. Are bilingual children confused? Does bilingualism make children smarter? Is it best for each person to speak only one language with a bilingual child? Should parents avoid mixing languages together? Is earlier better? Are bilingual children more likely to have language difficulties, delays, or disorders? This article is organized around these six common questions.

1. Are bilingual children confused?

One of the biggest concerns that parents have about raising children in a bilingual household is that it will cause confusion. But is there any scientific evidence that young bilinguals are confused? The first question to ask is what confusion would look like. Except in the case of neurological disorders ( Paradis, 2004), fluently bilingual adults can speak whatever language they choose in the moment, and are clearly not confused. But what about bilingual children and infants?

One misunderstood behavior, which is often taken as evidence for confusion, is when bilingual children mix words from two languages in the same sentence. This is known as code mixing. In fact, code mixing is a normal part of bilingual development, and bilingual children actually have good reasons to code mix ( Pearson, 2008). One reason some children code mix is that it happens frequently in their language communities-children are just doing what they hear adults around them do ( Comeau, Genesee, & Lapaquette, 2003). A second reason is that, just like young monolinguals, young bilinguals are sometimes limited in their linguistic resources. Similarly to how a monolingual 1-year-old might initially use the word "dog" to refer to any four-legged creature, bilingual children also use their limited vocabularies resourcefully. If a bilingual child does not know or cannot quickly retrieve the appropriate word in one language, she might borrow the word from the other language ( Lanza, 2004). Rather than being a sign of confusion, code mixing can be seen as a path of least resistance: a sign of bilingual children's ingenuity. Further, bilingual children do not seem to use their two languages haphazardly. Even 2-year olds show some ability to modulate their language according to the language used by their conversational partner ( Genesee, Boivin, & Nicoladis, 1996). There is also evidence that children's early code mixing adheres to predictable grammar-like rules, which are largely similar to the rules that govern adults' code mixing ( Paradis, Nicoladis, & Genesee, 2000).

What about bilingual infants? Again, the research is clear: bilingual infants readily distinguish their two languages and show no evidence of confusion. Languages differ on many dimensions-even if you don't speak Russian or Mandarin, you can likely tell one from the other. Infants are also sensitive to these perceptual differences, and are particularly attuned to a language's rhythm. Infants can discriminate rhythmically dissimilar languages like English and French at birth ( Byers-Heinlein, Burns, & Werker, 2010; Mehler et al., 1988), and by age 4 months they can tell even rhythmically similar languages like French and Spanish apart ( Bosch & Sebastián-Gallés, 1997, 2001; Nazzi, 2000). Bilingual infants may be even more sensitive than monolinguals when it comes to discriminating languages. Recent research has shown that 4-month-old monolingual and bilingual infants can discriminate silent talking faces speaking different languages ( Weikum et al., 2007). However, by 8 months of age, only bilinguals are still sensitive to the distinction, while monolinguals stop paying attention to subtle variations in facial movements ( Sebastián-Gallés, Albareda-Castellot, Weikum, & Werker, 2012; Weikum et al., 2007). Instead of being confused, it seems that bilingual infants are sensitive to information that distinguishes their languages.

2. Does bilingualism make children smarter?

Popular books such as The Bilingual Edge ( King & Mackey, 2009), and articles such as The Power of the Bilingual Brain ( TIME Magazine; Kluger, 2013) have touted the potential benefits of early bilingualism. One of the most important benefits of early bilingualism is often taken for granted: bilingual children will know multiple languages, which is important for travel, employment, speaking with members of one's extended family, maintaining a connection to family culture and history, and making friends from different backgrounds. However, beyond obvious linguistic benefits, researchers have investigated whether bilingualism confers other non-linguistic advantages ( Akhtar & Menjivar, 2012).

Several studies have suggested that bilinguals show certain advantages when it comes to social understanding. In some ways, this is not surprising, as bilinguals must navigate a complex social world where different people have different language knowledge. For example, bilingual preschoolers seem to have somewhat better skills than monolinguals in understanding others' perspectives, thoughts, desires, and intentions ( Bialystok & Senman, 2004; Goetz, 2003; Kovács, 2009). Young bilingual children also have enhanced sensitivity to certain features of communication such as tone of voice ( Yow & Markman, 2011).

Bilinguals also show some cognitive advantages. In particular, bilinguals appear to perform a little bit better than monolinguals on tasks that involve switching between activities and inhibiting previously learned responses ( Bialystok, Craik, & Luk, 2012). Although these advantages have been mostly studied in bilingual adults ( Costa, Hernández, & Sebastián-Gallés, 2008) and children ( Bialystok & Martin, 2004), new evidence suggests that even bilingual infants ( Kovács & Mehler, 2009a, 2009b) and toddlers ( Poulin-Dubois, Blaye, Coutya, & Bialystok, 2011) show cognitive advantages. Additionally, there is some evidence that bilingual infants are advantaged in certain aspects of memory, for example generalizing information from one event to a later event ( Brito & Barr, 2012).

Research has not been able to determine exactly why these advantages arise, but there are several possibilities. Bilingual adults have to regularly switch back and forth between their languages, and inhibit one language while they selectively speak another. Some researchers suspect that this constant practice might lead to certain advantages by training the brain ( Green, 1998). Amongst infants, the need to constantly discriminate their two languages could also play a role ( Sebastián-Gallés et al., 2012). However, it is important to note that bilingualism is not the only type of experience that has been linked to cognitive advantages. Similar cognitive advantages are also seen in individuals with early musical training ( Schellenberg, 2005), showing that multiple types of enriched early experience can promote cognitive development. Regardless of origin, it should be noted that the "bilingual advantage" has sometimes been overplayed in the popular press. So far, bilingual cognitive advantages have only been demonstrated using highly sensitive laboratory-based methods, and it is not known whether they play a role in everyday life. Thus, the reported advantages do not imply that bilingualism is an essential ingredient for successful development.

3. Is it best for each person to speak only one language with a bilingual child?

One popular strategy for raising bilingual children is "one-person-one-language," a strategy first recommended over 100 years ago ( Ronjat, 1913). Theorists originally reasoned that associating each language with a different person was the only way to prevent bilingual children from "confusion and intellectual fatigue." While appealing, this early notion has been proven false. As discussed above, there is no evidence that bilingual children are confused by early bilingualism, and the cognitive benefits associated with bilingualism run counter to the notion of "intellectual fatigue."

It is still important to consider what strategies families can use to promote early bilingual development. Research has shown that a one-person-one-language approach can lead to successful acquisition of the two languages ( Barron-Hauwaert, 2004), but that it does not necessarily lead to successful acquisition of the two languages ( De Houwer, 2007). Further, children who hear both languages from the same bilingual parent often do successfully learn two languages ( De Houwer, 2007). A one-person-one-language approach is neither necessary nor sufficient for successful bilingual acquisition.

Several other factors have proven to be important to early bilingual development. These factors might lead some families to use a one-person-one-language strategy, and other families to use other strategies. First, it is important to remember that infants learn language through listening to and interacting with different speakers. Infants need to have a lot of exposure to the sounds, words, and grammars of the languages that they will one day use. Both quality and quantity matter. High quality language exposure involves social interaction-infants do not readily learn language from television ( DeLoache et al., 2010; Kuhl, Tsao, & Liu, 2003), and low-quality television viewing in infancy has been linked to smaller vocabulary sizes in bilingual toddlers ( Hudon, Fennell, & Hoftyzer, 2013). Opportunities to interact with multiple different speakers has been linked to vocabulary learning in bilingual toddlers (Place & Hoff, 2010).

Quantity can be measured by the number of words that children hear per day in each language. Quantity of early exposure has a profound effect on children's ongoing language development: hearing more words gives children a greater opportunity to learn a language, which leads to later advantages in school performance ( Hart & Risley, 1995). For bilingual children, it is important to consider the quantity of their exposure to each language. While a bilingual's two languages do influence each other to a certain degree ( Döpke, 2000), in many ways they travel on independent developmental paths. Bilingual children who hear a large amount of a particular language learn more words and grammar in that language ( Hoff et al., 2012; Pearson & Fernández, 1994), and show more efficient processing of that language ( Conboy & Mills, 2006; Hurtado, Grüter, Marchman, & Fernald, 2013; Marchman, Fernald, & Hurtado, 2010). Bilingual parents thus need to ensure that their children have sufficient exposure to the languages they want their children to learn. We return to this topic in the next sections.

Relatively balanced exposure to the two languages is most likely to promote successful acquisition of both of the languages ( Thordardottir, 2011). In situations where each parent spends equal time with a child, one-parent-one-language can be a great way to ensure equal exposure. Conversely, exposure to a second language only when grandma and grandpa visit on the weekend, or when a part-time nanny visits on a few weekdays, or when a language class meets on Thursday nights, will not lead to balanced exposure. Imagine an average infant who sleeps about 12 hours a day, and so is awake 84 hours per week. A single afternoon (~ 5 hours) is only about 6% of the child's waking life, and this exposure alone is unlikely to lead to acquisition of a language. Similarly, in homes where one parent is the primary caregiver, a one-parent-one-language is unlikely to lead to balanced exposure.

Unfortunately, providing perfectly balanced exposure in the early years will not necessarily ensure later bilingualism. As children become older, they become more aware of the language spoken in the community where they live, and are likely to use this language at school. This is known as the majority language, while other languages that are not as widely spoken are known as minority languages. Even if initially learned in preschool, minority languages are much more likely than majority languages to be lost as development continues ( De Houwer, 2007). Many experts recommend providing slightly more early input in a minority than in a majority language, and where possible providing children with opportunities to play with other kids in that language ( Pearson, 2008). Raising a bilingual child in communities that are largely bilingual such as Miami (Spanish-English), Montreal (French-English), and Barcelona (Catalan-Spanish) provides fewer challenges for ensuring the ongoing use of the two languages.

So what language strategies should parents use? The best answer is that parents should use whatever strategy promotes high-quality and high-quantity exposure to each of their child's languages. This could include structured approaches such as using different languages as a function of person (one-person-one-language), place (one language at home, one language outside), or time (alternating days of the week, or mornings/afternoons). Some parents insist on speaking only one language with their child, even if they are able to speak the other ( Lanza, 2004), to ensure exposure to a particular language. Other families find that flexible use of the two languages, without fixed rules, leads to balanced exposure and positive interactions. Each family should consider the language proficiency of each family member as well as their language preference, in conjunction with their community situation. Families should regularly make an objective appraisal of what their child is actually hearing on a daily basis (rather than what they wish their child was hearing), and consider adjusting language use when necessary.

4. Should parents avoid mixing languages together?

Many parents of bilingual children are bilingual themselves ( Byers-Heinlein, 2013). Code mixing-the use of elements from two different languages in the same sentence or conversation-is a normal part of being a bilingual and interacting with other bilingual speakers ( Poplack, 1980). Code mixing is relatively frequent amongst bilingual parents as well ( Byers-Heinlein, 2013), and even parents who have chosen a one-parent-one-language strategy still code mix from time to time ( Goodz, 1989). But what effects does hearing code mixing have on the development of bilingual children?

Research on the impact of code mixing on bilingual children's development is still quite limited. One study of 18- and 24-month-olds found that high amounts of code mixing by parents was related to smaller vocabulary sizes ( Byers-Heinlein, 2013). However, other studies have found no relationship between code-mixed language and early language development ( Place & Hoff, 2011). Further, studies are beginning to reveal that bilingual children as young as 20-months are able to understand code-mixed sentences, and show similar processing patterns as bilingual adults ( Byers-Heinlein, 2013). This would suggest that bilinguals are able to cope with code mixing from an early age. It has also been suggested that while code mixing might make word learning initially difficult, it is possible that practice switching back and forth between the languages leads to later cognitive benefits ( Byers-Heinlein, 2013). Unfortunately, the jury is still out on whether exposure to code mixing has developmental consequences for bilingual children, but we are currently working on several research projects that will help answer this question.

It is important to note that considerations of code mixing also have important social implications. In some communities, code mixing is an important part of being bilingual and being part of a bilingual community. For example, code mixing is the norm in some Spanish-English communities in the U.S., and Afrikaans-English code mixing is the norm in some parts of South Africa. Different communities have different patterns of and rules for code mixing ( Poplack, 1984), and children need exposure to these patterns in order to learn them.

5. Is earlier better?

Many people are familiar with the concept of a "critical period" for language acquisition: the idea that humans are not capable of mastering a new language after reaching a certain age. Researchers disagree about whether a critical period exists at all, and they disagree about when this critical period may occur-proposals range from age 5 to 15 ( Krashen, 1973; Johnson & Newport, 1989; Lenneberg, 1967). Disagreement aside, research on bilingualism and second language learning converges robustly on a simple take-home point: earlier is better. There may not be a sharp turn for the worse at any point in development, but there is an incremental decline in language learning abilities with age ( Birdsong & Molis, 2001; Hakuta, Bialystok, & Wiley, 2003).

This point is best understood as an interaction between biological and environmental factors. Researchers have argued that biological change during the first two decades of life results in a reduced capacity for learning and retaining the subtleties of language ( Johnson & Newport, 1989; Weber-Fox & Neville, 2001). In other words, our brains may be more receptive to language earlier in life. But importantly, our environment is also more conducive to language learning earlier in life. In many cultures and in many families, young children experience a very rich language environment during the first years of life. They hear language in attention-grabbing, digestible bundles that are targeted skillfully at their developmental level ( Fernald & Simon, 1984). Caregivers typically speak in ways that are neither too simple nor too complex, and children receive hours and hours of practice with language every day. This high-quality and high-quantity experience with language-a special feature of how people communicate with young children-often results in successful language learning. It gives children rich, diverse, and engaging opportunities to learn about the sounds, syllables, words, phrases, and sentences that comprise their native language. But beyond the first years of life, second language learning often happens very differently. Older children and adults do not usually have the same amount of time to devote to language learning, and they do not usually experience the advantage of fun, constant, one-on-one interaction with native speakers. Instead, they often find themselves in a classroom, where they get a small fraction of the language practice that infants and toddlers get ( Lew-Williams & Fernald, 2010). In classrooms, words are defined for them and grammar is described to them. Defining and describing can be effective, but they are not as powerful as discovering language from the ground up.

Applied to bilingualism, these maturational and environmental differences between younger and older learners indicate that it is most advantageous to learn two languages early on in life. Bilinguals who learn two languages from birth are referred to as simultaneous bilinguals, and those who learn a first language followed by a second language-whether as toddlers or as adults-are referred to as sequential bilinguals. The evidence points to fairly robust advantages for simultaneous bilinguals relative to sequential bilinguals. They tend to have better accents, more diversified vocabulary, higher grammatical proficiency, and greater skill in real-time language processing. For example, children and adults who learn Spanish as a second language typically struggle to master Spanish grammatical gender (e.g., "is it el gato or la gato?"), while people who learn Spanish and English from birth show reliable and impressive ease in using grammatical gender ( Lew-Williams & Fernald, 2007, 2010).

However, parents should not lose hope if they have not exposed their children to each language from birth. Infants' brains and learning environments are special and non-recreatable, but there are many other ways to foster bilingual development. Here we overview two possibilities. First, some parents (particularly those who can afford childcare) choose to hire bilingual nannies or send children to bilingual preschools, in order to maximize their children's exposure to another language. This can certainly result in increased bilingual proficiency, but it is essential to provide continued opportunities to practice each language once the child is older. Parental expectations should be quite low if children do not have opportunities to continue learning and using a language throughout development. However, keep in mind that bilingual exposure does not necessarily translate to being a bilingual who is able to understand and speak a language fluently. Researchers generally consider a child to be bilingual if he or she receives at least 10-25% of exposure to each language ( Byers-Heinlein, under review; Place & Hoff, 2011; Marchman et al., 2010; Marchman, Martínez-Sussmann, & Dale, 2004), but this level of exposure by no means guarantees functional bilingualism ( De Houwer, 2007).

Second, there are language immersion programs in elementary schools in many of the world's countries, including the U.S. and Canada. Their goal is to promote bilingualism, biliteracy, and multicultural proficiency among both language-majority and language-minority students. In the U.S., hundreds of immersion programs have been established in the last four decades in such languages as Spanish, French, Korean, Cantonese, Japanese, Mandarin, Navajo, and Hebrew. There are currently 434 or more immersion programs in 31 U.S. states ( Center for Applied Linguistics, 2011). French immersion programs are available in all 10 Canadian provinces, with enrolment ranging from 2-32% of students depending on the province ( Statistics Canada, 2000). Immersion programs confer advantages over other formats of language instruction that are typical in high school and college classrooms. In immersion programs, the second language is not necessarily a topic of instruction, but a vehicle for instruction of other curriculum subjects. In terms of the quantity of language exposure, immersion classrooms do not rival infants' language environments. However, they often foster functional bilingualism, and equip children with language skills that help them in later educational and professional contexts.

The take-home messages about bilingual language exposure are clear: more is better, and earlier is better. If you are 75 years old and you have always wanted to learn Japanese, start now. Language learning becomes more challenging with time, for both maturational and environmental reasons, but for those who are motivated ( Gardner & Lambert, 1959), it is never too late to learn a new language.

6. Are bilingual children more likely to have language difficulties, delays, or disorders?

Bilingual children are not more likely than monolingual children to have difficulties with language, to show delays in learning, or to be diagnosed with a language disorder (see Paradis, Genesee, & Crago, 2010; Petitto & Holowka, 2002). Parents' perceptions are often otherwise-they feel that their child is behind due to their bilingualism-revealing an interesting disconnect from scientific findings. Science has revealed an important property of early bilingual children's language knowledge that might explain this misperception: while bilingual children typically know fewer words in each of their languages than do monolingual learners of those languages, this apparent difference disappears when you calculate bilingual children's "conceptual vocabulary" across both languages ( Marchman et al., 2010). That is, if you add together known words in each language, and then make sure you don't double-count cross-language synonyms (e.g., dog and perro), then bilingual children know approximately the same number of words as monolingual children ( Pearson, Fernández, & Oller, 1993; Pearson & Fernández, 1994).

As an example, if a Spanish/English bilingual toddler knows 50 Spanish words and 50 English words, she will probably not appear to be as good at communicating when compared to her monolingual cousin who knows 90 English words. However, assuming 10 of the toddler's Spanish words are also known in English, then the toddler has a conceptual vocabulary of 90 words, which matches that of her cousin. Even so, knowing 50 vs. 90 English words could result in noticeably different communication abilities, but these differences are likely to become less noticeable with time. This hypothetical example about equivalence in vocabulary is supported by research showing that bilingual and monolingual 14-month-olds are equally good at learning word-object associations ( Byers-Heinlein, Fennell, & Werker, 2013). This offers some reassurance that young bilinguals-like young monolinguals-possess learning skills that can successfully get them started on expected vocabulary trajectories. There is also evidence that bilingual children match monolinguals in conversational abilities; for example, when somebody uses a confusing or mispronounced word, or says something ambiguous, bilingual children can repair the conversation with the same skill as monolinguals ( Comeau, Genesee, & Mendelson, 2010).

Just like some monolingual children have a language delay or disorder, a similar proportion of bilinguals will have a language delay or disorder. Evidence that one bilingual child has a language difficulty, however, is not evidence that bilingualism leads to language difficulties in general. The challenge for pediatricians and for speech-language pathologists is to decide if a bilingual child does have a problem, or whether her errors are part of normal development and interaction between the sounds, words, and grammars of her two languages. If parents are worried that their bilingual child does have a delay, they should first consult their pediatrician. Pediatricians sometimes have a tendency to say, "Don't worry, her language is completely normal." This statement will end up being false for some children who will end up diagnosed with language difficulties, but it is more likely than not to be true, especially considering that parents can be inaccurate when estimating their bilingual child's language skills. In some other cases, health care providers with concerns about language impairment may recommend against raising a child in a bilingual environment. This recommendation is not supported by the science of bilingualism. Bilingual children with specific language impairments ( Paradis, Crago, Genesee, & Rice, 2003), Down syndrome ( Kay-Raining Bird et al., 2005), and autism spectrum disorders ( Peterson, Marinova-Todd, & Mirenda, 2012) are not more likely to experience additional delays or challenges compared to monolingual children with these impairments.

If parents do not feel comfortable with a pediatrician's opinion, they should find (or ask for a referral to) a speech-language pathologist with expertise in bilingualism, if at all possible. Early intervention increases the likelihood of a positive outcome. The problem is that few clinicians receive quality training about the learning needs of bilingual children, which in some cases leads to a misdiagnosis of bilingual children as having delayed or disordered language ( Bedore & Peña, 2008; Kohnert, 2010; Thordardottir, Rothenberg, Rivard, & Naves, 2006). The time is past due to eliminate such simple misunderstandings in clinical settings. A bilingual clinician, or an individual who has training in bilingualism, will take care in assessing language skills in both languages, in order to measure the child's entire language profile. Parents should keep in mind that clinicians have a very difficult job when it comes to assessing bilingual children. They have to (1) accurately assess a bilingual child's language abilities in each of her languages, (2) integrate the child's problematic and unproblematic abilities in terms of sounds, words, grammar, and conversation in each language into a coherent whole, (3) evaluate whether the child is delayed and/or disordered in one or both languages, (4) weigh the child's linguistic/cognitive capacities in comparison to typically and atypically developing monolingual children and, when possible, bilingual children of the same age, and (5) develop an effective intervention that targets subareas of linguistic/cognitive competence in one and/or both languages. This is a tangled landscape for intervention, but one that can be assessed thoughtfully. Regardless of whether parents pursue intervention, they can help children gain bilingual proficiency by using both languages as regularly as possible in enriching and engaging contexts. Furthermore, parents should keep in mind that both monolingual and bilingual children can best show off their skills when using language that matches their daily experiences ( Mattock, Polka, Rvachew, & Krehm, 2010).

In summary, if you measure bilinguals using a monolingual measure, you are more likely to find false evidence of delay. Fortunately, researchers and clinicians are now developing bilingual-specific measures that paint a more accurate picture of bilinguals' global language competence.

Conclusions

In this article, we have reviewed what the science says about six of parents' most commonly asked questions about early bilingualism. Research demonstrates that we need to reshape our views of early bilingualism: children are born ready to learn the language or languages of their environments without confusion or delay ( Werker & Byers-Heinlein, 2008). To promote successful bilingual development, parents raising bilingual children should ensure that their children have ample opportunities to hear and speak both of their languages. As children get older, interacting with monolingual speakers (especially other children) is important for motivating ongoing language use, especially for minority languages not widely spoken in the community ( Pearson, 2008). Teachers, pediatricians, and speech language pathologists play an important role in dispelling common myths, and in communicating science-based information about early bilingualism to parents.

While our focus here has been on language development, it is also important to recognize that early childhood is also a time of profound emotional, social, physical, and cognitive development. Bilingualism will be a priority or even a necessity for some families. Other families might choose to focus on other aspects of development. In some cases, where families are not fluent in a second language, early bilingualism might be unrealistic. Here, it is important to keep two things in mind: 1) bilingualism is only one way to promote successful early development, and 2) second language learning is possible at any age. Language-any language-is a window to the world. It is better for parents to provide plenty of input and interaction in a language they are comfortable in, than to hold back because they are not fluent or comfortable in the language.

When it comes to raising bilingual children, myths and misunderstandings are common, but facts are hard to come by. Together with researchers around the world, we are working hard to continue providing scientifically based facts addressing parents' most important questions about early bilingualism.

Acknowledgments

This work was supported by grants to Krista Byers-Heinlein from the Natural Sciences and Engineering Council of Canada and the Fonds de recherche du Québec - Société et culture, and to Casey Lew-Williams from the National Institute of Child Health and Human Development and the American Speech-Language-Hearing Foundation. Thank you to Alexandra Polonia for her assistance with proofreading, and to the many parents of bilingual children whose questions inspire and motivate us.

Biographies

Krista Byers-Heinlein (B.A., McGill University; M.A., Ph.D., University of British Columbia) is Assistant Professor in the Department of Psychology at Concordia University. She directs the Concordia Infant Research Laboratory, and is a member of the Centre for Research in Human Development, and the Centre for Research on Brain, Language and Music. She is recognized internationally for her research on bilingualism in infancy, and has published extensively on the topics of bilingual infants' speech perception and word learning.

Casey Lew-Williams (B.A., University of California, Berkeley; M.A., Ph.D., Stanford University) is Assistant Professor in the Department of Communication Sciences and Disorders at Northwestern University. He directs the Language Learning Lab, a research group devoted to studying first, second, and bilingual language learning. His work focuses in particular on understanding how different learning experiences shape language outcomes in diverse populations of infants, children, and adults.

Contributor Information

Krista Byers-Heinlein, Concordia University.

Casey Lew-Williams, Northwestern University.

References

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# data[].attributes.attachment_link.title
Bilingualism in the Early Years: What the Science Says

# data[].attributes.attachment_link.description
Many children in North America and around the world grow up exposed to two languages from an early age. Parents of bilingual infants and toddlers have important questions about the costs and benefits of early bilingualism, and how to best support language ...

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Special Education: Cognitive & Motor Disabilities, Department of Education & Pedagogy, Utrecht University, Utrecht, Netherlands

Amsterdam Center for Language and Communication, Amsterdam, Netherlands

Fryske Akademy, Leeuwarden, Netherlands

Faculty of Arts and Social Sciences, Maastricht University, Maastricht, Netherlands

Meertens Institute, Amsterdam, Netherlands

Many studies have shown that bilingual children outperform monolinguals on tasks testing executive functioning, but other studies have not revealed any effect of bilingualism. In this study we compared three groups of bilingual children in the Netherlands, aged 6-7 years, with a monolingual control group. We were specifically interested in testing whether the bilingual cognitive advantage is modulated by the sociolinguistic context of language use. All three bilingual groups were exposed to a minority language besides the nation's dominant language (Dutch). Two bilingual groups were exposed to a regional language (Frisian, Limburgish), and a third bilingual group was exposed to a migrant language (Polish). All children participated in two working memory tasks (verbal, visuospatial) and two attention tasks (selective attention, interference suppression). Bilingual children outperformed monolinguals on selective attention. The cognitive effect of bilingualism was most clearly present in the Frisian-Dutch group and in a subgroup of migrant children who were relatively proficient in Polish. The effect was less robust in the Limburgish-Dutch sample. Investigation of the response patterns of the flanker test, testing interference suppression, suggested that bilingual children more often show an effect of response competition than the monolingual children, demonstrating that bilingual children attend to different aspects of the task than monolingual children. No bilingualism effects emerged for verbal and visuospatial working memory.

Introduction

Over the past few years many studies have shown that bilingual children outperform monolinguals on tasks measuring executive functions (for reviews, see Adesope et al., 2010; Barac and Bialystok, 2011; Hilchey and Klein, 2011). The executive functions are part of a domain-general cognitive system that is essential for the flexibility and regulation of cognition and goal-directed behavior ( Best and Miller, 2010) and comprises distinguishable yet interrelated components ( Miyake et al., 2000). Commonly referred to components are switching (switching flexibly between tasks or mental sets), updating (constant monitoring and rapid addition/deletion of working-memory contents), and inhibition (control of attention and ability to override a strong prepotent response) ( Miyake et al., 2000), although more recent insights suggest that inhibition may not be separable from the other components ( Miyake and Friedman, 2012). Bilinguals are thought to develop executive function advantages because they manage multiple languages and continuously monitor the appropriate language for each communicative interaction ( Costa et al., 2009). They need to attend to cues that inform the speaker on which language to use, select the right language, and choose appropriate lexicalisation, and while doing this they suppress the interference of other languages. As such, interactions in bilingual contexts may call upon general conflict-monitoring and goal-orienting abilities ( Colzato et al., 2008; Costa et al., 2009; Hernández et al., 2013), leading to general executive function advantages (see Bialystok et al., 2012, for an overview).

However, other studies conclude that bilinguals' better executive function outcomes are a mere artifact of experiments ( Paap et al., 2015) or that bilingual cognitive advantages are attributable to factors such as differences in socioeconomic status (SES) between monolinguals and bilinguals ( Morton and Harper, 2007). Other factors have also been proposed to account for the bilingual-monolingual differences in executive function tasks, such as general intelligence ( Craik and Bialystok, 2005; Arffa, 2007; Brydges et al., 2012) or culture ( Carlson and Choi, 2008; Carlson, 2009). To prevent confounding effects, within-group comparisons ( Wu and Thierry, 2013; Crivello et al., 2016) and between-group comparisons in which the groups are matched on a range of background variables ( Hilchey and Klein, 2011) are needed.

One study noteworthy for its careful design has been conducted by Duñabeitia et al. (2015). They compared the inhibitory skills of 252 monolingual Spanish and 252 Basque-Spanish bilingual children using a verbal and a numerical Stroop task in which children had to ignore distracting information. The monolingual children were recruited from provinces where Spanish is the only official language of communication. The bilingual children were recruited from the Basque country where both Basque and Spanish are official languages. Children in the two groups were matched on age, academic skills, attention-related skills, and intelligence. In this study no effects of bilingualism emerged on either of the two Stroop tasks. Furthermore, a large-scale study conducted with Welsh-English bilinguals showed little support for bilingual advantages on non-verbal executive function tasks (card sorting tasks, Simon tasks) and metalinguistic tasks ( Gathercole et al., 2014). In both studies a relatively wide age range was included, but breaking down the results by grade or age group did not alter the conclusions.

Gathercole et al. (2014) suggest that it might not be coincidental that the Basque-Spanish and Welsh-English studies showed no effects of bilingualism, as the bilinguals in the two studies grew up in a situation of bilingual immersion in which both the minority language (Basque, Welsh) and the state's official language (Spanish, English) are part of the everyday experience. Assuming a gradual approach to bilingualism, as for instance proposed by Dijkstra (2005) and Lam and Dijkstra (2010), they suggest that fluent bilinguals, such as the Basque-Spanish and Welsh-English bilinguals, have strong between-language links and a large degree of automaticity of the linguistic knowledge in both languages. Consequently, switching between languages may require little cognitive effort and control, and as a result, does not lead to the supposed training effect. Various other studies in which the bilinguals are also immersed in both the minority language and the state's official language do show cognitive effects of bilingualism: balanced Frisian-Dutch children outperform Dutch-dominant children ( Bosma et al., 2017), and Spanish-Catalan bilinguals ( Costa et al., 2008, 2009; Hernández et al., 2013), Sardinian-Italian bilingual children ( Lauchlan et al., 2013; Garraffa et al., 2015) and children who speak Cypriot Greek and Standard Modern Greek ( Antoniou et al., 2016) outperform Spanish, Italian, and Greek monolinguals, respectively, on tasks testing executive functioning. It is possible that the participants in these studies are less bilingually fluent than the Basque-Spanish and Welsh-English bilinguals who showed no cognitive effects of bilingualism, because being immersed in the two languages does not necessarily imply fluent bilingualism. The hypothesis seems to be at odds, however, with observations showing that cognitive advantages are limited to bilinguals who are proficient in both languages ( Carlson and Meltzoff, 2008; Bialystok and Barac, 2012; Poarch and van Hell, 2012; Videsott et al., 2012; Weber et al., 2016) or emerge as an effect of growing bilingual proficiency ( Blom et al., 2014; Antoniou et al., 2016; Crivello et al., 2016).

Unlike the Basque-Spanish and Welsh-English bilinguals, the Frisian-Dutch, Catalan-Spanish, Sardinian-Italian bilinguals, and Cypriot Greek-Standard Modern Greek bidialectals are exposed to two closely related languages or dialects. This may suggest that language distance modulates the cognitive effect and that cognitive advantages are more likely for closely related varieties than for very distinct languages. However, there are also studies on closely related varieties that observe no cognitive effects suggesting that the relevant factor that might affect the emergence of the bilingual cognitive advantage in executive functioning is not language distance. For instance, no effects were observed in bilinguals who speak Italian and a Venetian regional variety ( Scaltritti et al., 2015) or English and Dundonian, a regional variety spoken in the north-east of Scotland ( Ross and Melinger, 2016). The conclusion that language distance does not modulate the cognitive effect of bilingualism is furthermore supported by research by Bialystok and colleagues who report effects of bilingualism on executive functioning in different language pairs (French-English, Chinese-English) and in heterogeneous bilingual samples ( Bialystok, 1999; Bialystok and Martin, 2004; Bialystok et al., 2005). Comparing the Catalan-Spanish ( Costa et al., 2008, 2009; Hernández et al., 2013) and Italian-Venetian contexts, Scaltritti et al. (2015) suggest that the frequency of language switching and mixing may explain the differential findings as the sociolinguistic environment of Catalan-Spanish bilinguals is conducive to language switching, whereas language use in the Italian-Venetian context is more compartmentalized. However, according to Green and Abutalebi (2013) separation may be more fundamental than frequency of switching, as functioning in settings in which the two languages are more separated is more likely to be associated with heightened cognitive control than functioning in dense code-switching contexts. The role of language separation appears to be supported by the findings of Antoniou et al. (2016) who observed cognitive effects in a context of diglossia in which the two language varieties (Cypriot Greek and Standard Modern Greek) are functionally separated and show hardly any overlap between domains of language use.

Despite the many studies that have investigated the cognitive effects of bilingualism, it is still not well-understood which conditions moderate the effect of bilingualism on executive functioning. With the present study, we aimed to shed more light on this issue by comparing three groups of 6- to 7-year-old bilingual children with a monolingual control group in the Netherlands. The four groups are matched on age, non-verbal intelligence, parental education, and gender. They differ in lingual status on two dimensions: besides the bilingual versus monolingual divide, the bilingual groups differ in exposure to a regional versus migrant language. In these two types of bilingualism, exposure to the minority language (i.e., regional, migrant) is not the same because exposure to the migrant language happens predominantly in the home environment, whereas the regional languages are also frequently spoken outside the children's homes in the wider society. Children in the two regional language groups are exposed to either Frisian or Limburgish, apart from the national language (Dutch). Like Dutch, Frisian and Limburgish are West Germanic languages. Frisian and Limburgish share many linguistic properties with Dutch, but they are among the most linguistically distant from standard Dutch ( Heeringa and Nerbonne, 2013). The sociolinguistic context is different for Frisian and Limburgish, which will be explained below.

Frisian is spoken in the province of Fryslân, in the north of the Netherlands, where it is an official language besides Dutch. As such, primary schools in the region are obliged to teach Frisian for at least 1 h per week, and in many schools Frisian is used as one of the languages of instruction. As Frisian has a long history of literacy and is present as language of instruction in education, Dutch and Frisian are considered and in general produced by its speakers as two separate varieties, even though code-mixing between Frisian and Dutch does happen regularly ( Muysken, 2000). Frisian is recognized under part III of the European Charter for Regional and Minority Languages (ECRML), which went into force in 1998. This obliges the Dutch government to take concrete measures to promote Frisian in domains such as education, administration, and the media. In 2005, Frisian was recognized by the Dutch government as the only national minority language under the Framework Convention on the Protection of National Minorities. In 2014, the Wet Gebruik Friese Taal ('Law on the use of the Frisian language') went into force in the Netherlands, which states that Frisian and Dutch are the official languages of the province of Fryslân. Frisian has quite a strong position in the province, although it is more spoken in rural, than in urban areas ( Breuker, 2001). In a recent survey of the province, slightly more than half of the population reported to speak Frisian as a mother tongue (55.3%) and slightly less than half of the population reported to speak Frisian with their partner (45.6%) and children (47.5%). Frisian is more used orally than written: most inhabitants of the province of Fryslân reported speaking it well (66.6%), but only few reported writing it well (14.5%) ( Provinsje Fryslân, 2015).

Limburgish is spoken in the province of Limburg, in the south of the Netherlands. The dialects of Dutch Limburg were extended minor recognition under the label Limburgish in 1997 by the Netherlands, a signatory of the 1992 ECRML. Minor recognition under ECRML compels the Dutch state to formally recognize the status of Limburgish as a separate variety without, however, being obliged to take relevant measures such as financial support. Moreover, Limburgish is not taught in schools and, hence, it does not have the same status as Frisian. Since 1997, public funds have been made available by the Province of Limburg for promoting the use of Limburgish, although most people in Limburg, if not all, use the label dialect instead of Limburgish. Its use in local media is restricted ( Cornips et al., 2016), as is its use in writing, public speech, educational contexts, and administration although, in contrast to Frisian, it is spoken as much in rural as in urban area's (with the exception of the former coal mining area in the south-east). Although use of Limburgish is often limited to homely matters of family and community life ( Leerssen, 2006) such as in the street, and in shops, it is also commonly spoken in formal domains, for instance by the highest-ranking provincial dignitaries and policy-officers in the provincial government building ( Cornips et al., 2016). Therefore, it has a high social prestige in some societal and cultural domains. According to research conducted by the newspaper De Limburger/Limburgs Dagblad of a representative sample of 1,078 respondents in spring 2016, 66% indicated to be exposed to Limburgish from birth onward and 9% claimed to be raised partly in Limburgish. Moreover, 59% of the respondents claimed to be highly proficient in speaking the dialect of their birthplace and, in addition, 46 and 69% reported to be highly proficient in speaking and understanding the dialect of the village where they currently live in, respectively. Limburgish is spoken most with one's own partner (64%) or children (62%) at home, with one's parents (66%), and with friends (71%). In contrast, Dutch is the dominant language at the workplace or at school (53%), in civil services (65%), and in the hospital (75%). Although Limburgish and Dutch are perceived as two separate varieties, people frequently code-mix or speak a leveled variety between Dutch and Limburgish dialect in daily contexts ( Giesbers, 1986).

The third bilingual group consists of Polish-Dutch immigrant children. Since 2004, when Poland entered the European Union, there has been an increase of Polish labor immigrants in the Netherlands. Recent demographic statistics indicate that there are 137,794 Polish immigrants in the Netherlands. The majority is first generation immigrant (78%) ( Centraal Bureau voor de Statistiek [CBS], 2015). In general, Polish immigrants in the Netherlands have a higher educational level than the four largest immigrant groups (that is, migrants from Morocco, Netherlands Antilles and Aruba, Suriname, Turkey), and particularly Polish women are relatively well-educated ( Dagevos, 2011). In our sample, the educational level of the Polish group was even higher than expected, which allowed us to match the four groups on SES. Because the influx of immigrants from Poland is relatively recent, limited information is available on language abilities and use in this group. The study by Dagevos (2011) reports that most Polish immigrants have a low level of Dutch and a good command of Polish. Both the low level of Dutch and high level of Polish are most probably related to recency of migration and are expected to change as a function of length of stay in the Netherlands. A minority of the Polish immigrants reports to always speak Dutch with their partner (20%) or children (10%). The reason why more Dutch is used with partners than children is twofold: relatively many Polish immigrants are in mixed marriages and many do not yet have children who are born in the Netherlands. It may be expected that use of Dutch in the Polish migrant families will increase when more children are born and educated in the Netherlands.

Executive function tasks in this study tested attention and working memory. Working memory refers to the ability to retain information in an accessible state ( Engle, 2002). Various studies have shown that performance on working memory tasks is strongly related to attention, specifically to attentional control ( Engle and Kane, 2004) and focus ( Cowan et al., 2005). Attention and working memory are, however, not isomorphic and are best represented by correlated but distinct factors ( Unsworth and Spillers, 2010). Previous research has shown bilingual advantages in attention ( Martin-Rhee and Bialystok, 2008; Engel de Abreu et al., 2012), working memory ( Morales et al., 2013; Blom et al., 2014) and in a combination of attention and working memory tasks ( Antoniou et al., 2016), using similar tasks as those used in the present study. The attention tasks in the present study tested the ability to filter information and focus on task-relevant stimuli (selective attention) and the ability to suppress interference from a specific cue (interference suppression). For working memory, both verbal and visuospatial working memory tasks were used ( Alloway et al., 2006).

We expected the bilingual children to outperform the monolingual children on working memory and attention, but because there are also studies reporting no effects, we reckoned with the possibility that no effects would emerge. There could also be reasons why some bilingual groups differ from the monolinguals whereas others do not. Exposure to Polish in a limited number of domains (because of in-home exposure only) may result in a relatively low degree of bilingual proficiency in the Polish group. Given previous observations that a certain level of bilingual proficiency is required for cognitive effects to develop ( Carlson and Meltzoff, 2008; Bialystok and Barac, 2012; Poarch and van Hell, 2012; Videsott et al., 2012; Blom et al., 2014; Antoniou et al., 2016; Crivello et al., 2016; Weber et al., 2016), it is possible that the Polish group shows no bilingual benefit, in contrast to the Frisian and Limburgish groups. The Polish group is not as bilingually immersed as the Frisian and Limburgish groups, where both languages are used frequently inside and outside the home environment. Given this difference, children in the Frisian and Limburgish groups may be more fluent bilinguals and experience more overlap in the domains of language use than the Polish children. Fluent bilingualism ( Gathercole et al., 2014) and limited language separation ( Green and Abutalebi, 2013) may predict that the Frisian and Limburgish groups do not outperform the monolinguals on executive functioning, and contrast with the Polish group in this respect. Between the Frisian and Limburgish contexts, differences exist in use of the regional language in school settings. Teaching Frisian as a subject in school may contribute to language separation, because it raises awareness that Frisian is a separate language. This would predict that the Frisian children are more likely to show cognitive effects of their bilingualism than the Limburgish children. However, the use of Frisian as a language of instruction, besides Dutch, could have the opposite effect because functional overlap between the two languages in a specific domain, like the educational context, may lead to less separation instead of more.

Materials and Methods

Participants

In the study 176 children participated, who were assigned to four different groups (monolingual Dutch, Frisian-Dutch, Limburgish-Dutch, Polish-Dutch), with 44 children in each group. All children were either 6 or 7 years old (72-95 months) at time of testing. In addition to age, a number of selection criteria were used. Children with a non-verbal intelligence below 70 were excluded, as were children for whom full datasets were not available. Furthermore, within the bilingual groups, children were only included if at least one of their parents spoke the non-Dutch language with the child, to ensure that all these children could be considered bilingual. Details of the groups are given in Table 1.

The four groups did not differ in age [ F(3,172) = 1.13, p = 0.34, = 0.02]. In addition to age, they were matched on non-verbal intelligence [ F(3,172) = 0.20, p = 0.90, = 0.003], SES [ H(3) = 3.71, p = 0.30, = 0.004], and gender [χ ²(3) = 0.27, p = 0.97]. Non-verbal intelligence was measured with the short version of the Wechsler Nonverbal-NL ( Wechsler and Naglieri, 2008), and SES was indexed by the average educational level of both parents of the child, based on the Questionnaire for Parents of Bilingual Children (PaBiQ; Tuller, 2015). Educational level represented the highest degree obtained on a nine-point scale ranging from 1 indicating no education to 9 indicating a university degree.

The Frisian-Dutch, Limburgish-Dutch, and monolingual Dutch participants were recruited via regular elementary schools in the north, south, and mid-west of the Netherlands, respectively. All these children were born in the Netherlands. The Polish-Dutch children were recruited via Polish Saturday schools in the western part of the country. In the Polish group, 70% of the children were born in the Netherlands (mean age of arrival = 8.62 months, SD = 20.38). All Polish children had lived in the Netherlands for 2 years or more at time of testing. Parental questionnaire data, collected with the PaBiQ ( Tuller, 2015), indicated that the bilingual children had received a substantial amount of input in Dutch before the age of 4, measured relative to the total amount of language input that the child received before this age (both inside and outside home context). From the age of 4 onward, all children received regular and frequent exposure to Dutch in kindergarten. There was a difference between the bilingual groups with respect to Dutch input before age 4 [ F(2,129) = 4.83, p = 0.009, = 0.07]. The Frisian group had received less Dutch exposure than the Polish ( p = 0.01) children. There was no difference between the Frisian and the Limburgish group ( p = 0.07) or between the Polish and the Limburgish group ( p = 1.00). The PaBiQ also provided information on the current use of languages at home, measured relative to the total amount of language input that the child heard from its mother, father, siblings, and other adults that had frequent contact with the child. The groups did not differ on current use of Dutch [ F(2,129) = 2.06, p = 0.13, = 0.03]. The language input and use patterns at home in the three bilingual groups can be found in Table 2.

As expected, the bilingual children were quite proficient in Dutch as confirmed by the outcomes of the Dutch version of the Peabody Picture Vocabulary Test (PPVT; Schlichting, 2005), which is a standardized measure for Dutch receptive vocabulary. The data in Table 3 show that each group scored, on average, within the normal range of variation for monolingual Dutch children, that is, within 1 standard deviation from the mean of the normative sample ( M = 100, SD = 15). In the Polish sample there were six children who scored 1 standard deviation below the mean and one child who scored over 2 standard deviations below the mean. Most of these children were not born in the Netherlands but arrived at a later age, explaining these relatively low scores. On average the Polish group also had a lower PPVT score than the other three groups as indicated by a univariate ANOVA [ F(3,172) = 12.42, p < 0.001, = 0.18] and subsequent Bonferroni post hoc comparisons (monolingual: p < 0.001, Frisian: p < 0.001, Limburgish: p = 0.01). Further information about children's skills in Dutch and the non-Dutch language was obtained through the PaBiQ. The Frisian and Polish parents indicated quite similar skills in both languages [Frisian: t(43) = -0.78, p = 0.44; Polish: t(43) = -1.55, p = 0.13], whereas the Limburgish parents reported that their children's skills in Dutch were better than in Limburgish [ t(40) = -6.06, p < 0.001].

Measures

Receptive Vocabulary

Receptive vocabulary in Dutch was measured with the Peabody Picture Vocabulary Task (PPVT-III-NL; Schlichting, 2005, based on the PPVT-III by Dunn and Dunn, 1997). The PPVT is a standardized receptive vocabulary test designed for the age range from 2 years and 3 months to 90 years. It contains 204 items divided over 17 sets. The sets are ordered according to difficulty and each set consists of 12 items. In this task, the child hears a stimulus word and has to choose the correct referent out of four pictures. The PPVT-III-NL was administered and scored according to the official guidelines. Receptive vocabulary in Polish was measured with the standardized Obrazkowy Test Słownikowy - Rozumienie ( Haman and Fronczyk, 2012). This instrument is very comparable to the PPVT and offers monolingual norms for the age range from 2 to 6 years and 11 months. For Frisian and Limburgish, no standardized receptive vocabulary measures were available.

Parental Questionnaire

The Questionnaire for Parents of Bilingual Children ( Tuller, 2015) was administered during a home visit or telephone interview with one of the child's parents. For the bilingual children, the interview was conducted by bilingual assistants, who were proficient in both Dutch and Frisian/Limburgish/Polish and could therefore be carried out in the preferred language of the parent. For the monolinguals, the interview was in Dutch. The questionnaire administered to the parents of the monolingual children was a short version of the PaBiQ in which the items that were only relevant for bilingual children (e.g., amount of input in the different languages, skills in the non-Dutch language) were removed. As described under 'Participants,' the PaBiQ provided information on parental education, on the child's language input before the age of 4, on the current language use at home, and on the child's language skills as evaluated by the parent.

Working Memory

Verbal and visuospatial working memory were measured with a backward Digit Span task and a backward Dot Matrix task, respectively. These tasks were based on the Alloway Working Memory Assessment (AWMA; Alloway, 2012) and translated to Dutch by native to near-native speakers of Dutch and English. In the backward Digit Span task the children had to repeat sequences of auditorily presented digits in reverse order. In the backward Dot Matrix task the children were presented with sequences of blue dots that appeared in a 4 × 4 matrix on a computer screen. After the last dot disappeared, the children had to point out the position of the dots in reverse order. The tasks started with a block of six trials with sequences of one digit or dot, after which the difficulty level was gradually increased. The AWMA procedure was applied for scoring. One point was given for each correct trial, so there was a maximum of six points per block. Trials were scored as incorrect if children recalled one or more digits/dots incorrectly, if the sequence was incorrect, or if they omitted one or more digits/dots. Children automatically continued with the next block when they repeated the first four trials within one block correctly, in which case they received a score of 6, or when they repeated four of the first five trials within one block correctly, in which case they received a score of 5. The task stopped automatically when children responded incorrectly to three trials within the same block. There were six blocks in the Dot Matrix task and seven in the Digit Span task, so the scores could range from 0 to 36 for the Dot Matrix and from 0 to 42 for the Digit Span.

Attention

Selective attention was measured with the visual Sky Search task from the Test of Everyday Attention for Children ( Manly et al., 1999). In the Sky Search task, children had to look for identical pairs of spaceships on an A3 sheet of paper. The test sheet contained 20 identical pairs and 108 non-identical pairs. The children had to encircle the identical pairs as fast as they could while ignoring the non-identical pairs. They indicated themselves when they were finished. The time per target (i.e., an identical pair of spaceships) was calculated, which was the time it took children to do the task divided by the total number of correctly encircled pairs of spaceships. Selective attention was measured because the children had to focus on the identical pairs in order to perform well on the task. After completion of this sheet the children were given a second A3 sheet, which was the motor-control version of the task. On this sheet only the 20 pairs of identical spaceships were displayed. Again, they had to encircle all the pairs of spaceships as fast as they could; the time per target was calculated for this sheet as well. Children's selective attention score was then calculated by subtracting the time per target of the motor-control sheet (i.e., second sheet) from the time per target of the test sheet (i.e., first sheet). In this way drawing speed was controlled for.

Interference suppression was measured with a flanker test from Engel de Abreu et al. (2012), who adapted the child Attention Network Task from Rueda et al. (2004a, b). The task was administered on a laptop using the experimental software E-Prime 2.0 ( Schneider et al., 2002). In the Flanker task a horizontal row of five equally spaced yellow fish was presented to the children. The children were asked to indicate the direction of the central fish by pressing the corresponding left or right response button as quickly as possible. On congruent trials (50%), the flanking fish were pointing in the same direction as the central target fish, and on incongruent trials (50%), the flanking distractors pointed in the opposite direction. Each trial started with a fixation cross in the middle of the screen (1000 ms), followed by the presentation of the five fish. Children had to respond by pressing a left or a right button within 5000 ms. A response after 5000 ms was considered incorrect. All children completed two blocks of 20 trials in which presentation of congruent and incongruent trials was randomized. Eight practice trials preceded the test phase. Accuracy and reaction times (RTs) were documented automatically through E-Prime. As accuracy scores were very high in all groups and in both the congruent and incongruent conditions (>95% correct), we decided to focus on RTs in the analyses. Following Engel de Abreu et al. (2012), mean RTs were calculated excluding incorrect responses, RTs below 200 ms and RTs above 3 standard deviations of children's individual means (<5% of all trials). The flanker effect, reflecting the difference between the average RTs on incongruent and congruent trials (mean RT INCONGRUENT - mean RT CONGRUENT), was used as our dependent variable. A small flanker effect was assumed to indicate good ability to suppress interference, whereas a large flanker effect was thought to indicate limited resistance to interference.

Procedures

This research was screened by the Standing Ethical Assessment Committee of the Faculty of Social and Behavioral Sciences at Utrecht University. Criteria were met and further verification was not deemed necessary. Parents of participants gave informed consent in accordance with the Declaration of Helsinki. All participants were tested individually in a quiet room at their school or their home. The children completed a battery of tests, including several measures that tapped into language, working memory, and attention (not all relevant for the current study). The experimenters who administered the tests all had a native command of Dutch and, in the case of the bilinguals, also of Frisian, Limburgish, or Polish. The language of instruction for all relevant measures was Dutch, except for the Polish receptive vocabulary task, which was administered with Polish instructions.

Results

Comparisons between Groups

Table 4 shows the results of the monolingual and bilingual groups on the working memory and attention tasks.

In the case of the two working memory tasks (backward Digit Span, backward Dot Matrix) a higher score indicates better performance, but in the case of both attention tasks (Sky Search, Flanker) a higher score points to lower performance. The flanker effect showed substantial individual variation as indicated by the large standard deviations. Inspection of the individual scores revealed that these are caused by negative effects, indicating it took children longer to respond to the congruent than to the incongruent items. For reasons of interpretability we removed the negative flanker effects from the analyses below, but return to the issue at the end of the results' section because it concerns removal of a non-neglible amount of data (25%).

To test if the two working memory and the two attention tasks showed an effect of bilingualism, a multiple linear regression analysis was performed on each of the four different dependent variables. The distribution of the Sky Search deviated strongly from normality (skewness = 1.76, kurtosis = 3.74) and for this reason a log-transformation was applied which improved the distribution (skewness = 0.25, kurtosis = 1.78). We included age, non-verbal IQ scores, and parental education as covariates. In order to control for level of Dutch, which was the language of instruction, PPVT scores were included as a covariate as well. A binary variable Group (monolingual versus bilingual) was included to evaluate the effect of bilingualism. The predictors were entered simultaneously. Table 5 shows correlations between the background measures (age, non-verbal intelligence, SES, and PPVT) and between the dependent variables (backward Digit span, backward Dot matrix, Sky Search, positive flanker effect). The correlations show that the two working memory tasks correlate with each other and with the two attention tasks, whereas the two attention tasks do not correlate with each other. The outcomes of the regression analyses are summarized in Table 6.

Age had an effect on all dependent variables in the expected direction: a higher age predicted better performance. Non-verbal intelligence predicted both working memory outcomes, but it did not predict attention. Parental education had no effect on any of the variables, but this could be due to a relatively limited range and lack of variation, as indicated by the means and standard deviations in Table 1. Receptive vocabulary had an effect on all measures in interpretable directions: children with larger receptive vocabulary scores in Dutch performed better on the working memory and attention tasks. Group affected performance on the Sky Search, with a better score for bilinguals compared to monolinguals. Normal probability plots of the residuals indicated that the residuals are normally distributed for the backward Dot Matrix and Sky Search tasks. For the backward Digit Span task and flanker effect, the residuals showed a slight right-skew.

To determine which bilingual groups outperformed the monolinguals on the Sky Search, an ANCOVA with age, non-verbal IQ scores, SES, and PPVT as covariates, the four-level variable Group as the independent variable and the Sky Search as outcome variable was performed. This analysis did not reach statistical significance [ F(3,167) = 2.50, p = 0.06, = 0.04].

Exploring the Role of Proficiency in the Non-dutch Language

The data in Table 4 indicate that all three bilingual groups score, on average, better than the monolinguals on the Sky Search, but the Polish bilinguals show the least indications they may benefit from their bilingualism. The context in which the Polish children develop the non-Dutch language is generally less favorable than the bilingual immersion context of the Frisian and Limburgish children. To explore if a lack of Polish proficiency affected the outcomes, we divided the Polish sample into two equally sized subgroups with, according to parental report, low Polish skills (0-0.67; LPS) and high Polish skills (0.72-1.0; HPS). We then validated the binary split by comparing the Polish receptive vocabulary scores in the two groups. The LPS group scored considerably lower ( M = 57, SD = 13.5; raw scores) on Polish receptive vocabulary than the HPS group ( M = 70, SD = 12; raw scores) [ F(1,42) = 11.60, p = 0.001, = 0.22]. The LPS group received less Polish input before age 4 compared to the HPS group [ F(1,42) = 4.50, p = 0.04, = 0.10], and current use of Polish was lower in the LPS group than in the HPS group [ F(1,42) = 6.59, p = 0.01, = 0.14]. Dutch receptive vocabulary was the same in both groups [ F(1,42) = 0.48, p = 0.49, = 0.01].

We reran the ANCOVA for the Sky Search, with age, non-verbal IQ scores, SES, and PPVT as covariates and the four-level variable Group as the independent variable. The Polish-Dutch group was limited to the HPS subgroup, which scored on average 5.14 ( SD = 1.62) on the Sky Search. This time the effect of Group was significant [ F(3,146) = 2.92, p = 0.036, = 0.06]. Bonferroni pairwise comparisons indicated that the Frisian-Dutch children ( p = 0.01), Limburgish-Dutch children ( p = 0.03) and the Polish-Dutch children ( p = 0.03) outperformed the monolinguals. Visual inspection of the distribution revealed that one child in the Limburgish sample showed an out-of-range value. In order to test if this child did have a disproportional effect on the outcomes, we ran the analysis using bootstrapping. Based on 1,000 bootstrap samples, we found a significant difference between the Frisian-Dutch and the monolingual group, 95% CI [0.05-0.34], and also between the Polish-Dutch group and the monolinguals, 95% CI [0.03-0.42]. The difference between the Limburgish-Dutch group and the monolingual group did not reach significance, 95% CI [-0.02 to 0.35]. Running the ANCOVA for the Sky Search with age, non-verbal IQ scores, SES, and PPVT as covariates and the four-level variable Group as the independent variable, including only the Polish LPS subgroup, we also observed a significant effect of Group [ F(3,146) = 2.93, p = 0.036, = 0.06]. However, Bonferroni pairwise comparisons indicated that the Frisian-Dutch children ( p = 0.01) and the Limburgish-Dutch children ( p = 0.04) outperformed the monolinguals, but the Polish-Dutch children did not ( p = 0.85). Pairwise comparisons using bootstrapping to reduce the bias caused by the extreme value in the Limburgish sample revealed that the Frisian-Dutch children performed better than the monolinguals, 95% CI [0.05-0.34], but the Limburgish-Dutch, 95% CI [-0.01 to 0.34], and the Polish-Dutch groups, 95% CI [-0.19 to 0.22], did not differ significantly from the monolinguals. Note furthermore, that including only the Polish HPS group did not affect the outcomes of the two working memory tasks and the flanker effect, even though the HPS group also scored relatively well on these tasks. Moreover, including only the 50% children who were, according to parental report, the most skilled in Frisian and Limburgish did not result in a larger general effect of bilingualism nor did it lead to a significant effect in the Limburgish sample.

Negative Flanker Effects

As indicated above, 25% of the flanker data showed a negative flanker effect, instead of the expected positive flanker effect. Because this is a non-negligible amount of data, it is important to investigate if these data are distributed randomly. The children with negative and positive flanker effects turned out to be very similar in many respects. They did not differ in age [ F(1,174) = 0.22, p = 0.64, = 0.001], non-verbal intelligence [ F(1,174) = 0.11, p = 0.74, = 0.001], SES ( U = 2988, p = 0.77), and gender [χ ²(1) = 0.03, p = 0.86]. Interestingly, relatively more monolinguals than bilinguals showed a negative flanker effect [χ ²(1) = 7.92, p = 0.008]. Table 7 shows the distribution of the negative and positive flanker effects across the different groups.

In the monolingual sample, 41% of the children showed a negative flanker effect (ranging between -13.53 and -257.63). In the three bilingual samples, this percentage was lower: 18% of the Frisian children (range between -1.95 and -116.63), 25% of the Limburgish children (range between -2.25 and -636.66) and 16% of the Polish children (range between -10.49 and -299.58). The difference with monolinguals was significant for the Frisian [χ ²(1) = 5.46, p = 0.03] and the Polish children [χ ²(1) = 6.76, p = 0.02], but did not reach significance in the Limburgish group [χ ²(1) = 2.52, p = 0.17].

Discussion and Conclusion

In this study we compared three bilingual groups of 6-7-year-old children with a monolingual control group on two working memory (verbal, visuospatial) and two attention measures (selective attention, interference suppression). The three bilingual groups differed in sociolinguistic setting: two of the bilingual groups were exposed to a regional language (Frisian, Limburgish) in addition to the nation's dominant language (Dutch), and the third bilingual group consisted of children exposed to a migrant language (Polish) besides Dutch. The inclusion of different bilingual groups is relevant in light of the growing awareness that contextual factors moderate the effect of bilingualism on cognitive development ( Green and Abutalebi, 2013; Scaltritti et al., 2015; for an overview see the research topic of Yoshida et al., 2015, and the Bilingualism Forum, 2015 in Cortex). To exclude confounding effects, the four groups were matched on age, non-verbal intelligence, SES, and gender. The regional bilingual language groups and the monolingual group were culturally comparable. Multiple regression analyses, in which all bilinguals were grouped together and compared with the monolinguals, demonstrated that bilinguals outperformed monolinguals on selective attention. Pairwise comparisons of the separate bilingual groups and the monolingual controls suggest that the overall effect of bilingualism on selective attention was carried by the Frisian-Dutch children and the more bilingually proficient Polish-Dutch children. On the Flanker task, which tests the ability to suppress interference, monolingual and bilingual groups differed in the extent to which the incongruent flanking fish led to a slower or a faster response. The working memory tasks showed no effects of bilingualism.

These outcomes support the hypothesis that bilingualism influences the development of attention and confirm that effects of bilingualism on cognition are found across different sociolinguistic settings, that is, children acquiring a regional language ( Costa et al., 2008, 2009; Hernández et al., 2013; Lauchlan et al., 2013; Garraffa et al., 2015; Antoniou et al., 2016; Bosma et al., 2017) and children learning a migrant language ( Carlson and Meltzoff, 2008; Engel de Abreu et al., 2012; Blom et al., 2014). The data also indicate that the positive effect of bilingualism on the Sky Search is small, elusive, and dependent on sampling and task. For instance, the difference between monolinguals and bilinguals was rather robust in the Frisian sample. In contrast, in the Limburgish sample, the effect did not survive an analysis in which bootstrapping was used. Also, the Polish-Dutch group showed a positive effect of bilingualism, but only if 50% of the children with highest proficiency in Polish were included, confirming that a certain level of bilingual proficiency is required for the cognitive benefits to develop ( Carlson and Meltzoff, 2008; Bialystok and Barac, 2012; Poarch and van Hell, 2012; Videsott et al., 2012; Blom et al., 2014; Antoniou et al., 2016; Crivello et al., 2016; Weber et al., 2016). Lastly, the enhancing effect of bilingualism emerged in the Sky Search, which measured selective attention, but not in the Flanker task, which measured attentional control and specifically the ability to suppress interference, and the two working memory tests.

We were not surprised to find that the expected effect of bilingualism emerged in only one task. Much previous research focused on interference suppression, guided by the hypothesis that bilingualism affects inhibitory control because bilinguals continuously need to suppress the interfering language ( Green, 1998; Bialystok et al., 2004). However, Paap and Greenberg (2013) as well as Ross and Melinger (2016) showed that the findings on classic inhibition tasks, including Flanker tasks similar to the one we used in our study, are mixed. An increasing number of studies has observed bilingual advantages in tasks testing working memory ( Vejnović et al., 2010; Morales et al., 2013; Blom et al., 2014; Kaushanskaya et al., 2014; Delcenserie and Genesee, 2016). However, also with respect to working memory, the outcomes of research are mixed (see Discussion; Calvo et al., 2016). Chung-Fat-Yim et al. (2017, p. 370) suggest that the mixed results on inhibition and working memory tasks in previous research might be "because those components do not define crucial differences between monolingual and bilingual cognition." Instead, they hypothesize that selective attention is primarily influenced by bilingualism, a claim that finds support in our study in a surprisingly consistent way: three bilingual groups scored better than monolinguals on the same selective attention test. In two of the groups (Frisian, proficient Polish) this difference reached statistical significance.

Besides the Sky Search task, a Flanker task was used. In a previous study bilingual Portuguese-Luxembourgish children outperformed Portuguese monolingual children on this task ( Engel de Abreu et al., 2012). In our study this finding was not replicated, but a comparison of the positive and negative flanker effects revealed a different effect of bilingualism. Relatively many monolinguals showed a negative flanker effect, indicating that they were faster in the incongruent than in the congruent condition. The difference between monolinguals and bilinguals in the relative frequency of negative flanker effects was significant for the Frisian and Polish children, but, again, did not reach statistical significance in the Limburgish sample. To our knowledge, negative flanker effects have not been reported explicitly in the literature on bilingualism, despite the fact that the "direction of the flanker effect has been a topic of some controversy" ( Rouder and King, 2003, p. 288). It is conceivable that the negative flanker effects contribute to the elusiveness of the effects of bilingualism in studies using Flanker tasks ( Paap and Greenberg, 2013; Ross and Melinger, 2016).

Rouder and King (2003) ascribe the negative flanker effects to contrast enhancement in lower order perceptual processes early in stimulus processing. Positive flanker effects, in contrast, may reveal response competition in the response selection processes, which takes place later in stimulus processing. Possibly, bilingual children filter out less and attend to more information in their environment, because they are used to attending to many cues for deciding which language to use in their everyday life. The simultaneous processing of contrasting stimuli may, moreover, be common for bilingual children. This happens, for instance, when they interact in one of their languages while a movie is playing in the other language or when they listen to one language while reading the other language as can happen in the case of subtitles. More experience with the simultaneous processing of contrasting information might reduce the effect of contrast enhancement.

The relatively few negative flanker effects in the bilingual sample indicate that the bilingual children in our study more often show response competition which, in turn, demonstrates that they attend to the incongruent flanking fish more than the monolingual children did. However, it was not the case that the bilingual children were more bothered by the incongruent flanking fish, as shown by the absence of a difference when positive flanker effects were compared across monolinguals and bilinguals. Moreover, in the Sky Search task, in which the children were asked to focus on the contrast and compare two adjacent space ships to decide on their similarity, the bilingual children outperformed the monolinguals. This shows that when the children's task is to detect a contrast between stimuli, instead of ignoring interference from contrasting stimuli (as in the Flanker test), bilingual children excel. This supports the hypothesis that bilingual experiences change the way attention is directed to the environment and enhance selective attention ( Bialystok, 2015; Chung-Fat-Yim et al., 2017).

In our study two groups of regional language users were tested. In the Frisian sample, the effects of bilingualism were more robust than in the Limburgish sample, both for the Sky Search and for the flanker effect. Parents' ratings of their children's language skills in the two languages indicate that the Limburgish parents rated their children's skills in Limburgish rather low, which may suggest that a lack of bilingual proficiency is related to the less robust effect of bilingualism in the Limburgish sample. However, including only the 50% of the children with, according to parental report, high Limburgish proficiency did not alter the outcomes, suggesting that bilingual proficiency does not play a role. We suggested that teaching Frisian as a subject in school, which is obligatory for at least 1 h per week, may lead to more language separation in the Frisian context. A higher degree of language separation may be linked to cognitive effects of bilingualism ( Green and Abutalebi, 2013). However, in many schools Frisian is also used as a language for instruction, like Dutch. Functional overlap between the two languages may have the opposite effect and lead to less separation instead of more, although the direction of the effect may be dependent on specific language use strategies that could vary from school to school and from teacher to teacher (e.g., use of specific days for each language, different classrooms, different subjects, or use of both languages for the same subject, in the same classroom, and at the same day).

Interestingly, recent research comparing tweets in Fryslân and Limburg suggests that Limburgish is more often used in tweets than Frisian, but also that Limburgish is more frequently mixed with Dutch ( Trieschnigg et al., 2015), which is consistent with the findings by Giesbers (1989) showing frequent mixing between Limburgish and Dutch. Frequent mixing in the Limburgish context is, moreover, supported by the study of Francot et al. (in press) who observed that in a Limburgish word naming task, children used many mixed forms that had characteristics of both Limburgish and Dutch. If these cross-regional differences in language use are representative of the children in our sample, the Limburgish parents may have rated their children's Limburgish relatively low because of frequent mixing with Dutch or because their children's language use is not in accordance with the parents' normative idea of how a dialect should be spoken. Moreover, frequent mixing may suggest that between-language links are stronger for Limburgish and Dutch than for Frisian and Dutch, explaining why the effect of bilingualism on attention is more robust for the Frisian than for the Limburgish children ( Gathercole et al., 2014). If in the Limburgish context frequent mixing is indeed more common than in the Frisian context, the pattern is also in line with Green and Abutalebi (2013) who predict that dense code-mixing behavior is less associated with cognitive control than bilingual behavior in which different languages are used in different environments or both languages are used but with different speakers. The parental questionnaire in our study provided information on language use in the home environment and no information was available on patterns of language use outside of this context. For this reason, we refrained from investigating the influence of language separation and overlap. We do, however, consider this an important venue for future research on the cognitive effects of bilingualism.

This study revealed that cognitive effects of bilingualism are found in children who become bilingual because they are exposed to a regional language, in addition to the national language, and in children who become bilingual because (one of) their parents migrated. Comparisons of different tasks show that bilingual experiences primarily influence how children direct their attention to the environment: it appears that they consider more information to be potentially task-relevant and they are relatively successful at using this information in a task in which they need to focus and attend selectively, i.e., compare two paired stimuli and decide on their similarity. The findings in this study demonstrate that for migrant children, proficiency in the home or migrant language is essential for cognitive advantages to develop and suggest that the cognitive effects for regional language speakers are modulated by differences in sociolinguistic settings.

Author Contributions

All authors were involved in the conception and design of the study. EBl wrote the introduction, results and discussion and carried out the statistical analyses. EE contributed to the literature review and finalizing of the manuscript. TB and EBo drafted the method section and contributed significantly to the collection, processing and analysis of the monolingual and Frisian data respectively. LC enabled the collection of the Limburgish data. TB, EBo, LC, and EE revised the draft for critical content.

Funding

This study is funded with grants from the Dutch Organization for Scientific Research (NWO Vidi, NWO Aspasia) awarded to EBl, the Province of Fryslân, Road veur 't Limburgs, SWOL (Maastricht University/Chair Language Culture in Limburg of LC Maastricht University), Department of Linguistics (Amsterdam University), and Meertens Institute Amsterdam.

Conflict of Interest Statement

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.

Acknowledgments

We thank Marta Czarnecka and Kirsten van den Heuij for their efforts in recruiting and testing participants, coordinating the Limburgish project (van den Heuij), and processing of the Polish and Limburgish data respectively. We are furthermore grateful to all the children, parents and teachers who made this study possible.

References

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Cognitive Advantages of Bilingual Children in Different Sociolinguistic Contexts

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Many studies have shown that bilingual children outperform monolinguals on tasks testing executive functioning, but other studies have not revealed any effect of bilingualism. In this study we compared three groups of bilingual children in the Netherlands, aged 6-7 years, with a monolingual control group.

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FAQ: Raising Bilingual Children | Linguistic Society of America

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The research team, in collaboration with Dr Vasileios Pappas from the Kent Business School, University of Kent, achieved its breakthrough by adapting methodology from the field of economics to the study of bilingualism. The project analysed data from children educated through the medium of both Greek and English in UK schools, in comparison with monolingual children.

Eirini Sanoudaki, Senior Lecturer in Linguistics and senior academic in the project, explains:

'There is an obvious advantage in being able to communicate in more than one language; our findings show that learning two languages can have even more benefits for children's development. We asked children, for example, to remember and repeat as many numbers as they can, to ignore irrelevant information, and to shift quickly between different tasks: bilingual children were better overall than monolingual children.
These results are important for us here in Wales and indeed for bilingual communities across the world.'

The team will now expand its research to other languages, with a new project examining language and thinking skills in English-speaking children attending Welsh-medium education.

The study was co-funded by the Economic and Social Research Council Wales Doctoral Training Partnership and the Department of Linguistics in the School of Arts, Culture and Language at Bangor University.
The publication is freely available here.

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Bilingual children have more efficient thinking skills, new research reveals

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The study, published in the journal Behavior Research Methods, presents a breakthrough in the field of bilingual thought processes. By introducing a radical new method, researchers were able to measure children's thinking skills more accurately and comprehensively than ever before. Findings show that bilingual children are on average 6.5% more efficient in their thinking skills than monolingual children.

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It is important for your child to learn the language of the country and the mother and/or father's tongue. According to Patricia Kuhl, babies are geniuses. Babies have the ability to take "statistics" on what we are saying to them. Unlike adults, babies are able to absorb these "statistics" that we teach them at such a young age. After Patricia looked at a baby's brain under an MAG machine, it was observed that one part of the brain is stimulated which causes another to stimulate. After puberty, there is a systematic decline from this "genius" level. Due to this decline, it is important to teach your baby the native language as they grow.

According to Patricia, it is great to become bilingual at such a young age, but is this actually an easy task to complete? The answer is no. Throughout your child's development there are going to be struggles that must be anticipated. However, these struggles are normal development for a bilingual child. As a parent, try not to compare your child to a monolingual child's development because in early childhood stages, they will move faster with language. Your child will not learn both the environment and minor language by magic, but it doesn't mean it will feel impossible.

Going parallel when teaching both languages is the best way. The reason behind this is because if they speak in the minor language in one environment, then go off to school not knowing the country's language it can put your child in a very stressful situation. In this case, the child will pick up on the language of the country, but the minor language will regress faster. In addition to going parallel with both languages, parents must support the minor language in order for the child to comprehend the importance.

Now after understanding how bilingualism works in early childhood, let's break it down age by age...

Birth to 1 year old

Within the first year of your child's development, the child will react to sounds. This coincides with what Kuhl spoke about in her Ted Talk. Babies are citizens of the world, they can discriminate all the sounds of every language. By monitoring the sound, the baby will try to make the sound themself. This is when the "statistics" come into play, the child is figuring out what sounds to know and understand.

1-2 years old

During this period of development, the child understands the simplest statements in each language. Your baby will be able to utter neutral words such as "mom" and "dad" along with responding to their own name. In this stage, your child is still learning the very basics of each language by performing simple tasks and naming objects. As mentioned, monolinguals may be ahead in language development at this point. Monolinguals are usually able to start saying up to fifty words by a year and a half. But don't worry, your bilingual baby has a lot more information in their head. By one and a half, bilinguals will speak in mixed languages. For example, for each object or action, one concept is fixed in one of the two languages.

2 years old

Once your child turns two, you will really notice a difference in monolinguals. Monolinguals are at a stage where they have wordy sentences, but also simplify words. Bilinguals begin a period of language confusion. Bilinguals will get in a habit of choosing easier words from the well-known language for pronouncing and insert them into their sentences regardless of the language of the question. It is important to keep working with your child, they do not need to see a specialist, this is part of bilingual development.

3 years old

At the age of three, your child will begin to resist multilingualism. They are able to distinguish who speaks which language. At this point in time, it is important to consistently show support from both parents on the child becoming bilingual, especially with the resistance. At this age, the child will question why they need to keep talking in the minor language. Keep it parallel and simplified, your child will understand soon, it is part of the development.

4-5 years

In this stage, the child will begin to become a "natural" bilingual. The child begins searching for a match, not a translation. You will also begin to see progress in your child responding in the language they were asked in. By age five, your child will understand they speak two languages and are surrounded by two cultures. This can be an exciting time, as parents really see the progress in language development. Also, each language should reach the same level as it reaches for a monolingual child, such as vocabulary, spontaneous speech, and pronunciation.

6 years old

By six years old, your child should be pretty developed on bilingualism. Your child should be open to communication with peers and teachers. Overall, there is definitely a long period of time where you will doubt the development, but in the long run I can promise you it will pay off!

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Stages of Bilingual Development - Global Children School

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Stages of Bilingual Development How to Help Develop a Bilingual Child It is important for your child to learn the language of the country and the mother and/or father's tongue. According to Patricia Kuhl, babies are geniuses. Babies have the ability to take "statistics" on what we are saying to them.

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Encyclopedia on Early Childhood Development

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Elena Nicoladis, PhD, Monique Charbonnier, PhD, Anamaria Popescu, PhD Student

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Second Language/Bilingualism at An Early Age with Emphasis on Its Impact on Early Socio-Cognitive and Socio-Emotional Development | Encyclopedia on Early Childhood Development

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Many children grow up hearing and using more than one language.