A bilingual is not two monolinguals in one body . Within each bilingual, no matter how young, is a brain that is balancing and juggling two languages in one mind. Each time a word is spoken, it has to compete with its other-language equivalent. Whenever a word is heard, it must be correctly catalogued in the bilingual lexicon and matched with its corresponding language. This makes bilingualism one of the most constant brain games anyone can play, strengthening the mind during communication. The advantages reaped via this bilingual mental juggling can have benefits for broader mental function, beginning at early stages in life.
So what are the bilingual advantages for children? When comparing children who have been exposed to two languages, bilingual children, to their monolingual peers, who have only been exposed to one language, certain trends appear in favor of bilingualism. Bilingual children outscore their monolingual friends in tasks that involve symbolism. They are better at reorganizing information and ignoring misleading information . Because they are constantly, unknowingly choosing between their two languages in all communication, they become good at focusing on what information is important and what information can be ignored. They also tend to develop a stronger metalinguistic awareness than their peers. From having double the language input, bilingual children garner an attention to language structures and elements that monolinguals may not.
Language and cognition researchers use some tasks that mimic games that children already like to play. Remember the game Simon? A series of colors appear or light up and the player is tasked with repeated the colors in the same order. It starts of easy, but gradually gets more difficult as longer color sequences are added. Researchers use a similar task to gauge participants’ working memory, the type of memory that processes new, already-stored information. When five-year-old children play Simon, the bilinguals score better than their monolingual peers . This shows a bilingual advantage in utilizing information stored in working memory.
A prominent keyword now for researchers in the areas of cognition and bilingualism is executive control. Executive control is an umbrella term for a variety of cognitive processes including working memory and problem solving. It is typically developed later in childhood for all children. One research team tested whether bilinguals have added advantage in these areas by using a verbal fluency task . They asked groups of bilinguals and monolinguals at ages four, seven, ten, young adulthood, and older adulthood to name all the words they could think of that begin with a certain letter. This type of task tests word retrieval accuracy and requires executive control. The findings showed that all children improved into young adulthood, but the executive control requirements for bilinguals starting at ten years old were easier than for their monolingual peers. This illustrates that even though children don’t develop executive control functions until later childhood, their prior bilingualism at a young age helps them develop their cognitive skills.
Another advantage gained through early childhood bilingualism is memory flexibility. Brito and colleagues  looked at three groups of 18-month-old children, those with monolingual English exposure, bilingual Spanish-Catalan exposure, and bilingual English-Spanish exposure. Spanish and Catalan are closely related languages and Spanish and English are more different. The study found that both groups of bilingual children, regardless of the similarity of the two languages they know, had better memory flexibility than their peers who were exposed to only one language. When the bilingual groups were compared to trilingual 18-month-olds, they found there was no added advantage in memory flexibility to knowing a third language. Importantly, knowing two or more languages allows young children to more easily retrieve the memories they have previously stored, even in new contexts. They can then use this information to generalize what they have learned to new concepts they encounter.
While bilingualism has been and continues to be stigmatized in certain communities, new research into bilingualism and cognitive functions promise a bright future. Bilingual children are able to make cognitive gains from the task of bilingual language processing. As these children juggle two or more languages with every communicative encounter, they are growing their brains in the areas of executive function, like memory, problem solving, and cognitive control. From as early as 18 months, bilingual children’s minds are adapting to their environment by focusing on relevant information and improving learning. Of course there are many cultural, social, and educational benefits to bilingualism, but the research discussed here supports a cognitive bilingual advantage. As a child’s bilingual language skills develop, so does their brain.
 Grosjean, F. (1989). Neurolinguists, Beware! The bilingual is not two monolinguals in one person. Brain and language, 36, 3-15.
 Bialystok, E., Craik, F.I.M., & Luk, G. (2012). Bilinguals: consequences for mind and brain. Trends in Cognitive Sciences, 16(4), 420-450.
 Friesen, D.C., Luo, L., Luk, G., & Bialystok, E. (2015). Proficiency and control in verbal fluency performance across the lifespan for monolinguals and bilinguals. Language, Cognition and Nueroscience, 30(3), 238-250.
 Brito, N.H., Sebastián-Gallés, N., & Barr, R. (2015). Differences in language exposure and its effects on memory flexibility in monolingual, bilingual, and trilingual infants. Bilingualism: Language and Cognition, 18(4), 670-682.