The study, which appears in the journal Child Development, adds to existing research on the differences in school readiness among income groups.
The research team, led by Clancy Blair, a professor in the Department of Applied Psychology at NYU’s Steinhardt School of Culture, Education, and Human Development, focused on a specific set of cognitive processes, referred to as executive functions. Executive functions are important for regulating behavior, managing new and potentially confusing information, adjusting to school, and making academic progress in the early elementary grades.
Previous studies with adults have shown that executive functions, which develop rapidly in early childhood, are compromised by stress. Researchers in the study reported in Child Development asked whether or not executive functions in early childhood are similarly influenced by stress in children’s lives.
Looking at almost 1,300 young children in mostly low-income homes, they examined aspects of children’s early environment between 7 and 24 months, including demographic characteristics, the household environment (such as safety and noise levels), and the quality of parenting (for example, levels of mothers’ sensitivity, detachment, and intrusiveness when interacting with their children). They also examined one indicator of stress—by measuring levels of cortisol, the stress hormone, in the children—and administered a battery of three tests related to executive functions when the children were 3 years old.
Their results showed that children from lower-income backgrounds experienced worse home environments, received less positive parenting, and had higher levels of cortisol in their first two years than children in slightly better-off homes. Even after controlling for income, home environment, and parenting, cortisol remained higher in African American children relative to white children. Importantly, higher levels of cortisol were associated with lower levels of executive function abilities for all children and cortisol was shown to mediate the effects of early disadvantage on this key aspect of cognitive development in early childhood.
“In sum, early stresses in the lives of children living in poverty affect how these children develop executive functions that are important for school readiness,” explains Blair.
The study was supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and the National Institute on Drug Abuse.
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