How do bilingual children represent languages in their mind?


Besides the importance given to the relationship between language and cognition

Researchers have showed a great deal of interest in the nature of language representation in the child’s mind with investigations focusing on whether children at very early stages represent in their mind the language input they receive, in a single or dual language system.

From the 20thcentury to the early 1990s, researchers seemed to find a general consensus on the fact that children do not acquire language bilingually at an initial phase. This concept is expressed by a very influential hypothesis during that time, the Unitary Language System Hypothesis, postulated by Virginia Volterra and Traute Taescner (1978).

According to the scholars, bilingual children begin acquiring a second language with a single language system which combines the words and the grammatical rules from their dual language input. According to them, only after the age of 3 the child starts to differentiate the languages which are channelled into two separate language systems.

On the contrary, Fred Genesee (1989) advanced an alternative view: The Dual Language System Hypothesis, according to which children exposed to two languages from birth establish two separate linguistic systems which, however, are not necessarily independent and autonomous.

The Dual Language System hypothesis appears to be supported  by recent research for what concerns speech perception, phonology, vocabulary and morphosyntax.  

Bilingual Code Mixing is not a sign of confusion

Another distinctive behaviour of bilingual speakers is Bilingual Code Mixing (BCM), which usually takes place when two languages are mixed in the same or in two different utterances in the same conversation. The amount of code-mixing varies in bilingual children, with some who code-mix frequently, some others a little and some children code-mix at different rates with different family members. Virtually all bilingual children code-mix even if their parents adhere to the “one-parent, one-language” principle; that is when each parent communicate to their child in one language only. Empirical research extensively supports BCM, which appears to be a normal phenomenon in dual language development. Furthermore, code-mixing does not occur only in bilingual children as it is common among adult bilinguals and highly proficient language learners. In this field, a vast body of research demonstrates that such individuals are able to create a flawless conversation when mixing both languages. Therefore, given the above conditions, code-mixing is believed to be a sign of proficiency in adults. Nevertheless, among children BCM has been thought to be, by parents and some professionals alike, a signal of confusion and cause of concern. In order to debunk this bilingual myth, it will be helpful, once again, to look into the Unitary Language System Hypothesis, according to which bilingual children are not able to differentiate their evolving languages at early development stages. Parents and professionals who believe in the validity of such a hypothesis, interpret code-mixing as a symptom of confusion, and in some instances as a sign of incompetence. As previously mentioned, such a hypothesis has been discredited by research that has exposed numerous shortcomings in the design methodology applied to these early studies. In fact, early research focused exclusively on how often bilingual children code-mixed and overlooked how frequently they could use their language in a sensitive context manner. A study conducted by Genesee et al, 1995 examined bilingual children between the ages of 22 and 26 months during naturalistic interactions. All the children were English-French bilinguals from Montreal, raised by their parents following the cited one-parent, one-language rule. The children were observed in three different contexts; alone with their mothers, alone with their fathers and in presence of both parents. In the latter context, the children were able to separate the two languages according to which parent they were interacting with. In this way, even at early ages, children were able to adjust their languages according to different contexts. These findings are incompatible with the Unitary Language System Hypothesis which would have expected the children to use random language despite diverse contexts. Furthermore, such results do not support the confusion hypothesis according to which children are not capable of becoming bilingual without experiencing language confusion. An integrative review of the subject is provided by Guiberson (2013), who did not find any evidence in the literature analysed to support such an assumption. Moreover, a recent study conducted by Greene et al., 2013, sustains the Lexical Gap Hypothesis (Paradis et al, 2011), according to which bilingual children code-mix not because they experience confusion or are not able to differentiate between their languages, but rather because they are filling the gaps in their lexical or syntactic knowledge in order to satisfy their communication needs. The scholars analysed code-mixed responses of 606 five-year old English and Spanish speaking children, and compared their prevalence, frequency and accuracy on expressive semantic items. The children were divided by language dominance established, based on the amount of language exposure and usage. In addition, they were allocated to a no-risk or at risk of language impairment group according to individual performance achieved in an English-Spanish screening battery. The results showed that the children used code-mixing to fill lexical gaps, which is consistent with other studies on children and adults. This study demonstrated once again that lexical choice and language preference requires linguistic competence in more than one language. To conclude, in most cases BCM should not be regarded as evidence of language delay or impairment; parents and educators should not admonish children for using it. Further, it is recommendable for language development specialists and educators to desist from advising parents to restrict their communication exclusively to one language on the postulation that this will correct any language learning problems.

The relationship between the child’s dominant and non-dominant language

As seen, a diversity of dynamics can influence the child’s dual language development, which do not seem to cause delays in early language development milestones. Also, beyond the early months, language development generally occurs in bilinguals within the normal range, as determined by monolingual children, for some language aspects, whilst it could lag behind monolinguals’ development  in some other aspects. Nevertheless, these differences do not lead to any difficulties in the child’s development and can be explained by examining, in most instances, the relationship between the child’s dominant and non-dominant language. In fact, it is unlikely for pre-school bilingual children to achieve a balanced proficiency in both languages, whilst most probably they will be dominant in one language. Also school age bilingual children could maintain a dominant language depending on the amount of language input they receive. Empirical research demonstrates that bilingual children could lag behind monolingual children in their non-dominant language in the vocabulary acquisition as bilingual children tend to have smaller vocabulary compared to their monolingual peers. This appears to be logical considering that bilingual children possess identical cognitive abilities and limitations related to memory capacity as monolingual children. Recent research confirms that language exposure influences bilingual children’s performance with regards to the acquisition of vocabulary. In fact, Thordadottir (2011) studied the performance of receptive and expressive vocabulary in 5 year old children of Montreal who were learning English and French simultaneously and compared their performance to monolingual children. The children had the same age, socio-economic status and non-verbal cognition. Also, the bilingual children spoke languages with equal status. The only variable was the amount of exposure to each language the children received across the bilingual process. Children exposed to both languages equally, achieved the same results as their monolingual peers in receptive vocabulary, whilst a greater exposure was required to attain the same monolingual’s outcomes in expressive vocabulary. In contrast to several previous studies, the bilingual children examined did not show a significant gap correlated to monolingual children in receptive vocabulary. This optimistic result could be attributed to the positive language-learning conditions for English and French in Montreal, but it could be also related to the fact that there is not a great typological distance between the two languages. Therefore, it seems reasonable to assume that bilingual children acquire vocabulary using the same mechanisms as monolingual children. Even though, their word repertoire in each language might be smaller, parents and professionals need to bear in mind that the size of their vocabulary will vary depending on the level language exposure they receive; influenced by the home, school and social environments. Another language domain subject to language exposure in young bilingual children, is morphosyntax, the process in which children start to use word combinations and produce simple utterances to express themselves. A widespread measure of children’s early morphosyntactic  development is “mean length of utterance” (MLU), (Paradis et al, 2011). Such a measure consists of establishing the average length of a child’s utterances, and it is calculated across a number of utterances produced by the child in a spontaneous speech. Most recently researchers have been interested in whether bilingual children’s MLUs augment with age at the same rate as monolinguals. Several studies have been conducted on the topic and they resulted in varied outcomes; showing a similar growth in MLU in bilingual children when they lived in favourable language learning environments, while the MLU appeared to be lower when the bilingual children’s non- dominant language lagged significantly behind their dominant language.

Children do not learn a second language overnight

Another popular belief is to think that children who are exposed to another language at late stage of bilingual development or after the age of 3 acquire a language overnight; indeed some people have the certainty that children “soak it up like a sponge”. Conversely, there is an extensive body of research revealing this myth to be false and that sequential bilingual children go through stages the lengths of which vary from child to child. According to Tabors (2008), second language learners (L2) experience 4 stages in early L2 development: 1) use of home language, 2)nonverbal period, 3)formulaic language use and finally 4)productive language use. The first stage refers to children speaking their home language in the host language environment; this stage is often very brief. During the second stage, the nonverbal period, children are elaborating the input in the L2 but produce a very few utterances or no words in L2; this stage can last for a few weeks to a few months with younger children usually experiencing this stage longer than older children. The social interaction and the L2 exposure have a major impact on L2 children at this stage. Follows stage 3 with the formulaic production of L2; children at this stage use very short utterances which most of the times are not original. Only at stage 4, children can use their L2 productively, however, the majority will not sound as native speakers as even young children can have a foreign accent and make mistakes in vocabulary or grammar. The lapse of time in second language development between when the learner begins to use the language productively until the learner attains a similar fluency as a native speaker, is usually referred to as Interlanguage, a term coined by Selinker in 1972. Interlanguage consists of a rule-governed linguistic system which exists on its own right and evolves over time; it is formed of developmental and transfer patterns which in the past were considered to be errors. In fact, transfer from L1 to L2 was seen as very detrimental to L2 learning, whilst most recently the effects of transfer have been also found to result into the right patterns and not only into errors. Despite the fascinating nature of Interlanguage, this review does not have the capacity to include a detailed research showing its characteristics, whilst it will carry on with exploring a controversial question which seems to be at the core of parents and professionals’ concerns; how long is needed for L2 children to reach native-speaker proficiency? The answer to this question is crucial, above all for those parents who are concerned when their child appears to acquire the L2 rather slowly. According to recent research sequential children acquire the L2 at different rates as they are influenced by internal and external factors. These factors are accountable for individual variations with the internal factors including motivation, personality, language aptitude, cognitive maturity and language distance typology.  External factors refer to the outside context where the child learns the L2 and consist of quantity and quality of L2 exposure at home and in the school environment; with the socioeconomic status (SES) of the family also playing a major role in predicting L2 competence. Johanne Paradis (2011), investigated how numerous internal and external child factors, predict the L2 acquisition of L2 children in terms of vocabulary size and accuracy with verb morphology. The scholar examined 169 children with an age between 4 and 7 years old, exposed to the English language for an average of 20 months. The children were members of families recently moved to Canada. Paradis (2011) found out that both factors were significant predictors of different outcomes in L2 children. However, she also discovered that internal factors such as language aptitude, age and L1 structure had a more substantial impact on individual variations than external factors.  Another study conducted by Chondrogianni et al, (2011), investigated the effects of child internal and external factors on the development of L2 English and Turkish speaking children belonging to a low socioeconomic status. Forty-three children were tested on the acquisition of vocabulary and morphosyntax; the data once again revealed that both language domains were influenced by both factors whilst, there was no significant impact of external factors on the development of tense morphology. To sum up, some children might be able to carry on an articulated conversation in L2 after only one year of schooling, whilst some  others might find themselves producing simple sentences after the same period of time. Whether L2 children will ever reach an identical fluency as native speakers remains still an open question that future research needs to investigate. Most importantly, parents and professionals should take the child’s internal and external factors into consideration before fearing language impairment. Above all, professionals should gather as much information as possible in order to rightly assess the child’s L2 competence.



Despite the general belief that bilingualism in young children is burdensome, intellectually challenging and even causes language delay, empirical research reveals that such assumptions are absolutely unfounded.  Indeed, dual language development takes different patterns from monolingual development at cognitive and linguistic levels, however, such differences mainly result in advantages of bilingualism in early childhood. It remains of crucial importance for educators and professionals to become familiar with recent research in order to rightly assess pre-school and school-age bilingual children. In fact, the wrong assessment could have negative consequences which affect the children not only in their childhood, but also in their adulthood. In order to avoid such a counter-productive prospect, the specific circumstances of each bilingual child must be taken into serious consideration. In addition, it will be helpful for professionals to desist from the idea of recommending parents to speak one language only to their child in order to prevent any language learning difficulty. It is indeed a bilingual myth to believe in such an idea and it is time for this myth to come to an end. Empirical research suggests that even children with language impairment have the capacity to acquire two languages at the same time. Bilingualism at early childhood should not be cause for concern, but a reason to rejoice as the child has the privilege to experience such a unique phenomenon. Future research should focus on whether school-age children will ever attain the identical native speaking fluency in their L2.



Berk, L. (2003). Child development. Toronto: Pearson Education Canada.

Bialystok, E. (2001). Bilingualism in development: Language, literacy, and cognition. New York: Cambridge University Press.

Bialystok, E. (2009). Bilingualism: The good, the bad, and the indifferent. Bilingualism: Language and Cognition, 12,pp 311, doi:10.1017/S1366728908003477

Bialystok, E., Barac, R.(2012). Bilingual Effects on Cognitive and Linguistic Development:Role of Language, Cultural Background, and Education. Child development, 83,2, 413-422

Bialystok, E., Barac, R., Blaye, A., Poulin-Dubois, D. (2010). Word Mapping and Executive Functioning in Young Monolingual and Bilingual Children. Journal of cognition and development, 11(4):485–508.

Bialystok, E., Craik, F.I.M., &Freedman, M. (2007). Bilingualism as protection against the onset of symptoms of dementia. Neuropsychologia, 45, 459-464.

Bialystok, E., Craik, F.I.M., Klein, R., & Viswanathan, M. (2004). Bilingualism, aging, and cognitive control. Psychology and Aging, 19, 290-303.

Bosch, L., & Sebastian-Galles, N. (2001). Early language differentiation in bilingual infants. In J. Cenoz & F. Genesee (Eds.), Trends in bilingual acquisition (pp.71-94). Amsterdam: John Benjamins.


Start learning a modern language with Languages Alive