Fifty years of research has revealed the sad truth that the children of lower-income, less-educated parents typically enter school with poorer language skills than their more privileged counterparts. By some measures, 5-year-old children of lower socioeconomic status (SES) score two years behind on standardized language development tests by the time they enter school.
In recent years, Anne Fernald, a psychology professor at Stanford University, has conducted experiments revealing that the language gap between rich and poor children emerges during infancy. Her work has shown that significant differences in both vocabulary and real-time language processing efficiency were already evident at age 18 months in English-learning infants from higher- and lower-SES families. By age 24 months, there was a six-month gap between SES groups in processing skills critical to language development.
Fernald's work has also identified one likely cause for this gap. Using special technology to make all-day recordings of low-SES Spanish-learning children in their home environments, Fernald and her colleagues found striking variability in how much parents talked to their children. Infants who heard more child-directed speech developed greater efficiency in language processing and learned new words more quickly. The results indicate that exposure to child-directed speech - as opposed to overheard speech - sharpens infants' language processing skills, with cascading benefits for vocabulary learning.
Fernald and colleagues are now running a parent-education intervention study with low-income Spanish-speaking mothers in East San Jose, California, funded by the W. K. Kellogg Foundation. This new program, called ¡Habla conmigo! (Talk with Me!), teaches Latina mothers how they can support their infants' early brain development and helps them learn new strategies for engaging verbally with their children. Although they only have data from 32 families so far, the preliminary results are promising. Mothers in the ¡Habla conmigo! program are communicating more and using higher quality language with their 18-month-olds compared to mothers in a control group.
"What's most exciting," said Fernald, "is that by 24 months the children of more engaged moms are developing bigger vocabularies and processing spoken language more efficiently. Our goal is to help parents understand that by starting in infancy, they can play a role in changing their children's life trajectories."