The authors of the study believe that children from higher income families with well-educated parents have an advantage because their parents not only talk to them more and use more complex sentences, but also use gesture to communicate more meanings to their children. This means that children from low income families are disadvantaged before they enter school.

"Vocabulary is a key predictor of school success and is a primary reason why children from low-income families enter school at a greater risk of failure than their peers from advantaged families," said Goldin-Meadow, the Beardsley Ruml Distinguished Service Professor in Psychology at the University and a leading expert on gesture.

The study investigated 50 Chicago children from a diverse range of socioeconomic backgrounds. The children's interactions with their primary caregivers during ordinary activities at home were videotaped in 90 minute sessions. The results showed that fourteen-month-old children from high-income, well educated families used gesture to convey 24 different meanings, while children from low income families conveyed only 13 meanings with gesture.

"It is striking that, in the initial stages of language learning when SES (socioeconomic status) differences in children's spoken vocabulary are not yet evident, we see SES differences in child gesture use," Rowe said. "Children typically do not begin gesturing until around 10 months. Thus, SES differences are evident a mere four months, and possibly even sooner, after the onset of child gesture production."

Once in school, students from higher-income families had a comprehension vocabulary of 117 (as measured by a standardized test), compared to 93 for children from lower-income families.

Reference

Rowe, M.L. & Goldin-Meadow, S (2009). "Differences in Early Gesture Explain SES Disparities in Child Vocabulary Size at School Entry," Science 13 February 2009: Vol. 323. no. 5916, pp. 951 - 953. DOI: 10.1126/science.1167025