Jamaica Stunting Study — Stimulation + Nutrition
University of the West Indies / World Bank · Kingston, Jamaica · 1986
Summary
The Jamaica study is remarkable for its long follow-up and the specificity of its finding: psychosocial stimulation (play, reading, structured interaction with caregivers) completely closed the 20-year earnings gap between stunted and non-stunted children, while nutritional supplementation alone did not. The study demonstrated that cognitive deprivation—not just physical malnutrition—drives the long-term effects of childhood stunting, and that it is reversible through relatively low-cost stimulation programs.
Research question
"Can psychosocial stimulation and nutritional supplementation overcome early childhood stunting's effects on development and adult earnings?"
Methodology
Intervention
Four arms: control, nutritional supplementation, psychosocial stimulation, stimulation + supplementation
Assignment
Randomized controlled trial (child)
Sample size
129 stunted children, followed to adulthood
Primary outcome
Cognitive development, educational attainment, adult earnings
Effect estimate
Stimulation arm: +42% adult earnings compared to control; fully closed the earnings gap with non-stunted peers after 20 years; supplementation alone had no significant long-term effect
Decision
Results shaped UNICEF and World Bank early childhood development policy globally; stimulation programs integrated into nutrition interventions worldwide
Result
Positive
Stimulation arm: +42% adult earnings compared to control; fully closed the earnings gap with non-stunted peers after 20 years; supplementation alone had no significant long-term effect
Evidence strength
Strong
Randomized controlled trial with large sample.
Replication status
Partially replicated
Institution
University of the West Indies / World Bank
Location
Kingston, Jamaica
Year
1986
Policy area
Early Childhood
Mechanism
Human capital