Researchers recorded all interactions between caregivers and children, from age 7 months to 3 years old, in different socioeconomic classes for 1 hour per week. This study presented the findings and implications for clinicians, educators, and policy makers.

Summary: The authors conducted this study to look for the cause of the disparity in linguistic/academic progress among children from different socioeconomic backgrounds. For 2.5 years, 7 month old children in 42 families were observed for one hour per week until the child turned 3 years old. Everything said to the baby, all talk the baby overheard, and everything the baby did or said during an hour of daily life was recorded and analyzed. Charts of monthly growth in vocabulary, utterances, and use of grammatical structures, as well as a list of 2,000 vocabulary words used during early language development are provided. The authors found the average welfare child had 1/2 as much experience per hour (616 words per hr.) as the average working class child (1,251 words per hr.), and less than 1/3 as much experience as the average professional class child (2,153 per hour). For example, in one year, extrapolating to a 100 hr. week (given a 14 hr. waking day), 11 million words for professional, 6 million words for working class, and 3 million words for welfare class were recorded. Parent talkativeness or “sociableness” to their infants accounted for a correlation between SES and the children’s later linguistic/academic development. For example, in low SES families, parent-child interaction tended to involve directives being given to the child whereas in higher SES background families the parent-child interaction tended to be more conversational. These are likely reasons why children from lower SES perform worse on standardized vocabulary tests than children from middle SES backgrounds. The study also demonstrated that the size of a child’s vocabulary could be based on experience and not necessarily attributed to an inherent language learning difficulty.

Importance: This study was one of the first to explicitly link vocabulary size to socioeconomic status rather than to the presence of a language disorder and demonstrated the importance of prior knowledge during assessment and intervention. This study also demonstrated the necessity of comparing a child to his speech community, as typical linguistic development and exposure varies depending on socioeconomic status as well as cultural perceptions and ideas about typical communication and language development in young children. Clinicians should be aware that static vocabulary tests and test items are most likely to identify the child’s SES background rather than the presence of a language disorder and therefore should not be used for diagnosis. When children come from at-risk backgrounds (e.g., low SES status) but do not appear to have a language impairment compared to peers, the clinician should consider alternatives in order to avoid inappropriately identifying language impairment. This could mean training parents, providing education about language stimulation, showing how to create a language rich environment, or adding language supports in the classroom through collaboration with classroom teachers.

Hart, B., & Risley, T. R. (1995). Meaningful differences in the everyday experience of young American children. Baltimore, MD: Paul H. Brookes Publishing Company.