Research Outcomes: First Language Exposure Can Improve Both Languages For Bilingual Children

Based on current research on bilingual development, immigrant parents can take comfort knowing that speaking in their first language to children does not prevent second language learning. Rather, the first language can help improve both languages.

Dr. Giang Thuy Pham is an associate professor at San Diego State University. She has conducted many studies on bilingual development in the early school years. These children spoke Vietnamese at home and learned English as the primary language of school. In addition, some children received Vietnamese lessons for 90 minutes per day as part of a school heritage language program. Although the following studies include children who speak Vietnamese and English, the findings can be applied to many bilingual groups.

These studies show that:

  1. Providing children many opportunities to use their first language in everyday life can help children retain and develop their skills.
  2. Teaching the first language (Vietnamese in this case) can improve both Vietnamese and English.
  3. As children grow up in an English-speaking country such as the US, they start to “think” in English and shift to the majority language of English.


Key Findings About Bilingual Development

1. Providing children many opportunities to use their first language in everyday life can help children retain and develop their skills.

Pham & Tipton (2018) explored different factors related to bilingual language development. There were 69 Vietnamese-English bilinguals ages five to eight years old in the study. They looked at factors internal and external to the child to see which factors were related to vocabulary outcomes in Vietnamese, English, or both languages. Internal factors included age, the ability to find patterns in pictures, and working memory. External factors consisted of how much of each language was spoken (language quantity) and how each languages was used in daily interactions (language quality). Information was collected from parents through phone surveys and from children through vocabulary tasks in Vietnamese and English.

Children on average scored higher on the vocabulary tasks in English than Vietnamese, showing a shift towards English and some degree of first language (Vietnamese) loss. Parental use of Vietnamese was not related to English vocabulary. That is, children continued to learn English whether or not there was parental support at home.  Unlike English, language quantity and quality mattered for Vietnamese. For children who had high Vietnamese skills, parents reported using more Vietnamese at home, with a greater number of activities in Vietnamese on a weekly basis.


2. Teaching the first language (Vietnamese in this case) can improve both Vietnamese and English.

Pham and Kohnert (2014) explored the lexical development of 33 Vietnamese-English bilingual children over a four-year time period, from kindergarten to third grade.  Each year, children completed two tasks that measured vocabulary size (the number of words children could name or understand), and two tasks that measured their processing skills (how quickly children could use words they already knew).

There were three main findings. First, there was growth in both languages. Children gained more vocabulary over time and became faster at using words they already knew.  Second, there were greater gains in English than in Vietnamese, especially for their ability to name vocabulary words. Finally, there was a shift from Vietnamese to English on the vocabulary skills measured by around eight years old.

With the same children in the four-year study, Pham (2016) studied the links between the vocabulary and grammar over time. For this study, children named pictures of objects and actions, and told stories when looking at picture books. The total number of different words used in the stories, average sentence length, and vocabulary in each language were measured.

The study had two main findings. First, there was a link between vocabulary and grammar within each language. The initial number of different words used to tell a story in one language predicted the length of the children’s sentences in that same language over time, and vice versa (children’s sentences predicted their future word use in the same language). This vocabulary-grammar connection was found within both Vietnamese and English. Second, the initial number of different words in the children’s first language (Vietnamese) predicted the number of different words used in their second language (English) later on. The opposite direction was not found English word use did not predict Vietnamese skills later on. The results suggest that focusing on children’s first language will contribute to gains in their second language. Yet, targeting children’s second language may not offer enough support for further improvement in their first language.


3. As children grow up in an English-speaking country such as the US, they start to “think” in English and shift to the majority language of English.

Even if bilingual children “think” more in English, their minds are not the same as monolinguals. Bilingual children still use strategies from both languages to extract meaning from sentences they hear.

Pham and Kohnert (2010) wanted to see how children who speak Vietnamese and English use cues from each language to process meaning. The study included 41 Vietnamese-English bilinguals and English monolinguals ages six to eight.

There were two tasks that everyone completed: picture naming and sentence interpretation. In the picture naming task, children named pictures on a computer screen of common objects and actions. For the sentence interpretation task, each sentence contained two nouns and one action word. Children listened to each sentence and tried to identify the “do-er” of the action. The sentences varied based on word order (order of nouns and the action word) and animacy (living nouns and non-living nouns).

The way bilingual children processed sentences was different from their monolingual peers. English monolinguals relied on the word order of nouns and verbs to help determine the “do-er”.  The bilinguals used both word order cues and animacy cues (whether the noun was a living thing or not). There was a positive relationship between Vietnamese language level and using animacy as a cue.

Pham and Ebert (2016) followed up with these children for three years to see whether their interpretation of the same set of sentences changed over time. They found that bilinguals continued to use both word order and animacy to select the “do-er” of the action.

Over time, children relied more on word order and less on animacy cues. Yet, their vocabulary skills continued to improve in both languages. This shows that there are “many roads that lead to Rome”.  Children learn to shift towards “thinking” in the majority language. Yet, they do not lose the ability to speak in their home language and often use strategies from both of their languages in communication.


Want to learn more about bilingualism? Check out Dr. Pham’s research lab, Bilingual Development in Context:


Pham, G. (2016). Pathways for learning two languages: lexical and grammatical associations within              and across languages in sequential bilingual children. Bilingualism: Language and Cognition,              19(5), 928-938.

Pham, G., & Ebert, K. D. (2016). A longitudinal analysis of sentence interpretation in bilingual                        children. Applied Psycholinguistics, 37(2), 461-485.

Pham, G., & Kohnert, K. (2010). Sentence interpretation by typically developing Vietnamese-English            bilingual children. Applied Psycholinguistics, 31(3), 507-529.

Pham, G., & Kohnert, K. (2014). A longitudinal study of lexical development in children learning                     Vietnamese and English. Child Development, 85(2), 767-782.

Pham, G., & Tipton, T. (2018). Internal and External Factors That Support Children’s Minority First                  Language and English. Language, Speech, and Hearing Services in Schools, 1-12.


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First Language Exposure Can Improve Both Languages for Bilinguals.