There is growing evidence to support that early childhood experience influences a child’s language comprehension and production ability by shaping how his/her brain grows and develops. It is important to understand which aspects of childhood experience are critical for a child’s language development.
A large number of studies have found that early childhood experince has a tremendous impact on how the brain grows and develops. The role of family socioeconomic status (SES) is particularly important in children’s language development while they are learning to speak. SES is a broad concept that indicates a family’s economic and social status relative to others, based on factors such as household income, and parents’ education and occupation. Researchers have estimated that children from higher-SES families had heard 30 million more words than children from lower-SES families by the age of 3, and found family SES can predict children’s language-related brain structure and function development, including gray matter volume and cortical thickness, as well as the brain’s activity in response to language stimuli.
Despite the influence from SES, there is evidence showing that language exposure, that is, the amount of spoken language a child hears, plays a considerable role in children’s development of language skills, as well as their language-related brain activity and structure development. Language exposure is the language quantity (e.g., number of words) and quality (e.g., sentence complexity, lexical diversity) that young children hear from their parents or community. Romeo and his colleagues demonstrated that children who had experienced more language exposure had better verbal abilities, for example, had a larger vocabulary and were better at speaking and understanding sentences, even after excluding the impact from the parents’ education and income levels. This means that children’s early language exposure is independently conducive to the development of children’s verbal ability, regardless of the family SES.
Their neuroimaging findings supported this argument again: Children who had more conversational experience with adults exhibited more activity in an area of the brain thought to be involved in speech production, called Broca’s area, and this trend was not subject to children’s family SES. These findings were extended by their following work about the relationship between language exposure and white matter connectivity. White matter connectivity is like a “neural highway” connecting brain areas to support certain functions. The left arcuate fasciculus is such a white matter tract which is thought to be important for language. It connects two cortical regions critical for language: Broca’s area and Wernicke’s area. Their work showed that the more adult-child conversations that young children had, the better developed their left arcuate fasciculus was, and this trend was not influenced by the SES. These results suggested that the development of language-related “neural highway” white matter connectivity was influenced by the child’s environment, specifically by early parent-child dialogic interaction.
In general, the above results indicate that the quality and quantity of early language experience could be a way to reduce the disadvantages lower family SES has on a child’s language development. In daily parent-child communication, when parents communicate effectively and frequently with their children, the child will increasingly play a more active role in the communication, which provides an advantage to the development of the child’s language skills. Additionally, frequent parent-child communication provides children with an opportunity for social interaction where they can learn to speak effectively for clear communication, which is not only necessary for their language skills but also for social development.
Romeo, R. R., Leonard, J. A., Robinson, S. T., West, M. R., Mackey, A. P.,& Rowe, M. L., et al. (2018). Beyond the 30-million-word gap: children’s conversational exposure is associated with language-related brain function. Psychological Science (4).
Romeo, R. R., Segaran, J., Leonard, J. A., Robinson, S. T., West, M. R., Mackey, A. P., … & Gabrieli, J. D. (2018). Language exposure relates to structural neural connectivity in childhood. Journal of Neuroscience, 38(36), 7870-7877.
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