The relationship between caregiver communication and children's brain development has been well established through research, but the the exact connection and specifics are not known. The "word gap" -- the difference between school-age children who grew up in lower income homes and their affluent peers is approximately 30 million fewer words for the children of lower socioeconomic status. This word gap has profound consequences for these students, with evidence demonstrating an influence of early language exposure on later language ability that suggests a potential influence of language experience in shaping brain structure.
Research in 1995 by Betty Hart and Todd R. Risley at the University of Kansas discovered a strong connection between spoken words and school performance in children, as well as an income based disparity in the quality of language children received (see here for a summary). Hart and Risley studied how parents of different socioeconomic backgrounds talked to their babies. Every month, the researchers visited the 42 families in the study and recorded an hour of parent-child interaction. When the children were 9, they examined how they were performing in school. Children whose families received government assistance heard about 600 words per hour, middle class children heard 1,200 words per hour, and children from professional families heard 2,100 words in an hour. By age 3, a poor child would have heard 30 million fewer words in his home environment than a child from a professional family. And the disparity mattered: the greater the number of words children heard from their parents or caregivers before they were 3, the higher their IQ and the better they did in school.
Why is the effect of talking on babies so profound? Results are not only predictive of academic success in general, but on reaching potentials in math, spatial reasoning, and literacy, the ability to self-regulate behavior, reaction to stress, and even perseverance. As shown by the recent study, the amount of adult-child conversational turns that young children experience is related to the strength of white matter connections between two key language regions in the brain, represented by the colored brain regions from two participants. Both children were the same age, gender, and had equivalent socioeconomic backgrounds, but differed in the number of conversational turns. This difference in conversational turns has effects on the white matter connections, as illustrated in the brain scans below (Romeo et al., JNeurosci 2018). These white matter connections occurred in all children who had parent-child conversations, regardless of socioeconomic status.
The difference in language is both in number and type of language: the children with greater conversational turns have heard more words, and also a different type and quality of words. In their neuroimaging study of 40 four- to six-year-old children and their parents, Rachel Romeo and colleagues found that greater conversational turn-taking was related to stronger connections between Wernicke's area and Broca's area; both regions that are critical for the comprehension and production of speech. These stronger connections develop early in life and are difficult, if not impossible to compensate for, even with early intervention programs aimed towards at-risk youth.
Parent talk in the first three years of life is the power propelling our brains to develop to their optimum potentials. The process is so simple and hidden that you aren’t even aware it’s happening. But in those first three years, when 85 percent of our physical brain growth occurs, parent talk is the brain’s essential nutrition. At no other time in life will brain growth be as robust or influential.
Allowing children the opportunity to develop the best and most diverse skill set possible is important, both as individuals and as a society. Parents often underestimate the influence they have in early education, and sometimes lack the resources necessary to access programs to help their children reach their full potential. Bringing awareness to the need for positive interaction and conversing with children about a variety of subjects from birth could be an important step to preparing kids for the skills they need to develop later in school.