Science: Childhood Interventions Improve Earnings for Disadvantaged Jamaicans

Early education and cognitive enrichment programs boosted the adult earnings of impoverished Jamaicans by 25%, according to the first long-term study of this type in a developing country.
At-home play sessions with these toys and others were used to boost cognitive development among Jamaican toddlers. | Courtesy of Susan Walker

Growth-stunted, impoverished Jamaican toddlers who received home educational sessions that promoted cognitive development had higher earnings as young adults than similarly disadvantaged children, a new study published in the 30 May issue of the journal Science reports.

The educational intervention increased participants' earnings by 25% over those who received no educational interventions, the researchers found, and even helped stunted children catch up to their healthy peers in terms of adult income.

This work marks one of the first studies to investigate the impact of early childhood development programs on the earnings of adults who grew up poor in a developing nation. Previous work in the field had focused on developed countries like the United States, showing that early childhood interventions there do indeed have significant long-term economic benefits.

University of California, Berkeley's Haas School of Business Professor Paul Gertler and colleagues suspected that programs that boost cognitive skills may have even higher benefits in developing nations, since children there often dwell in homes with less stimulating environments and may enter such programs with lower skill levels.

The researchers evaluated the earnings of young adult Jamaicans who had been enrolled in a randomized early childhood intervention program from 1986 to 1987, when they were between the ages of 9 and 24 months.

The original intervention, Dr. Gertler explained, was designed and implemented by Sally Grantham-McGregor, Emerita Professor of International Child Health at the Institute for Global Health, University College London. "Sally was among the first to realize and test the importance of psychosocial stimulation and the quality of parenting early in life."

The 129 children enrolled were from poor, disadvantaged neighborhoods in Kingston, Jamaica. The children all had stunted growth — the result of malnutrition — which has been linked to poor cognitive development.

The intervention included nutritional supplementation and psychosocial stimulation. Children in the study were assigned to one of four intervention types: nutritional supplementation, psychosocial stimulation, both, or neither.

Home visits by community health aides were a crucial part of the Jamaican interventions. | Courtesy of Susan Walker

Nutritional supplementation involved receiving one kilogram of formula containing 66% of daily-recommended calories every week for two years. Psychosocial stimulation involved two years of weekly one-hour play sessions at home with trained community health aides who guided mothers. Structured activities included playing educational games, labeling household items, responding to the child's vocalizations and actions, and using picture books and songs that facilitated language acquisition.

"A major focus of the weekly visits," Gertler explained, "was on improving the quality of the interaction between mother and child outside of the play sessions. At every visit, the use of homemade toys was demonstrated and the toys were left for the mother and child to use until the next visit when they were replaced with different ones.

"The intervention was innovative not only for its focus on structured activities to promote cognitive, language and socio-emotional development but also for its emphasis on supporting the mothers to promote their child's development," he added.

Twenty years later, the researchers found and re-interviewed most study participants. Those who had received the nutrition-only intervention experienced no long-term effect on their income, the researchers found. Meanwhile, the stimulation and stimulation-nutrition groups experienced such a similar income effect that the researchers analyzed them together in their study.

While the effects seen here in a developing country may vary from country to country, Gertler and his team are very excited about their results.

"These findings show that simple psychosocial stimulation through good parenting in early childhood for disadvantaged children can have substantial long term effects on human capital and labor market outcomes and can compensate for developmental delays," said Gertler. "The estimated impacts are substantially larger than the impacts reported for the U.S.-based interventions, suggesting that early childhood development interventions may be an especially effective strategy for improving long-term outcomes of disadvantaged children in developing countries."