An article in the New York Times was inspired by new research by Stanford psychologists. This research reveals that 2-year-old children of lower-income families may already be six months behind in language development.
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 score more than two years behind on standardized language development tests by the time they enter school.
Stanford researchers have now found that these socioeconomic status (SES) differences begin to emerge much earlier in life: By 18 months of age, toddlers from disadvantaged families are already several months behind more advantaged children in language proficiency.
In an experiment designed to investigate children’s vocabulary and language processing speed,Anne Fernald, a Stanford associate professor of psychology, enrolled 20 children, 18 months old, who lived near the Stanford campus, and tested how quickly and accurately they identified objects based on simple verbal cues. Follow-up tests six months later measured how these skills developed.
Research conducted in university laboratories commonly relies on a “convenience sample” of local participants who are usually affluent and highly educated. Since children in these higher SES families have many other advantages as well, the results of such research do not represent the majority of children living in less privileged circumstances in the United States.
To include a broader range of children in her research, Fernald took her lab on the road. She duplicated the experimental setup of her Stanford-based lab in a 30-feet-long RV and drove to a city a few hours north of campus, where the median household income and education levels are much lower on average than in the Bay Area.
The researchers recruited another 28 toddlers, aged roughly 18 months, from this lower SES population and performed the same experiments as they had on campus. Then they retested the children six months later when they turned 2 years old to see how they had progressed.
The results may seem depressing at first:
At 18 months, toddlers in the higher SES group could identify the correct object in about 750 milliseconds, while the lower SES toddlers were 200 milliseconds slower to respond.
“A 200-millisecond difference in response time at 18 months may not sound like much, but it’s huge in terms of mental processing speed,” Fernald said.
Both groups of children got faster with age, but at 24 months the lower SES children just barely reached the level of processing efficiency that the higher SES children had achieved at 18 months.
The researchers also asked parents to report on their children’s vocabularies at these age points. Between 18 and 24 months, the higher SES children added more than 260 new words to their vocabulary, while the lower SES children learned 30 percent fewer new words over this period.
Still the researchers do have some hope:
“It’s clear that SES is not destiny,” Fernald said. “The good news is that regardless of economic circumstances, parents who use more and richer language with their infants can help their child to learn more quickly.”
Abstract from the research:
This research revealed both similarities and striking differences in early language proficiency among infants from a broad range of advantaged and disadvantaged families. English-learning infants (n = 48) were followed longitudinally from 18 to 24 months, using real-time measures of spoken language processing. The first goal was to track developmental changes in processing efficiency in relation to vocabulary learning in this diverse sample. The second goal was to examine differences in these crucial aspects of early language development in relation to family socioeconomic status (SES). The most important findings were that significant disparities in vocabulary and language processing efficiency were already evident at 18 months between infants from higher- and lower-SES families, and by 24 months there was a 6-month gap between SES groups in processing skills critical to language development.