Dissertation Seminar-Daniel Hackman

TITLE: Socioeconomic status and the development of executive function and stress reactivity: The specific roles of parental nurturance and the home environment.   

Childhood socioeconomic status (SES) influences health, achievement, and psychosocial development.  Determining the effect of SES on the development of executive function (EF) and stress reactivity is a promising strategy to refine models concerning the mechanism by which SES affects these outcomes. Parental nurturance, life stress, and the quality of the home environment are candidate mediators of such SES effects.   In Study 1, I examined the effect of SES, measured by family income-to-needs and maternal education, on developmental trajectories of EF in early and middle childhood while comparing candidate mediation pathways.  Lower income-to-needs and maternal education in early childhood predicted worse performance on tasks of working memory, attention, impulsivity, and planning that emerge by the earliest age tested, 54 months.  No differences in developmental change were observed, but change in family income independently predicted concomitant changes in EF performance. Examining mediation without controlling for the correlation among candidate mediators led to overestimates of the magnitude of mediation pathways.   After adjusting for the correlations between candidate mediators, the early childhood home environment was a specific, partial mediator of income and education effects for all EF outcomes.  In Study 2, I examined the effect of SES, measured by parental education and neighborhood disadvantage, on EF development from middle childhood through adolescence. Lower parental education predicted worse working memory performance by age 10 that persists, but as in the previous study, did not predict developmental change.  It also predicted worse performance on two tasks of inhibition but greater improvement over time, such that differences decreased or did not persist through adolescence.   Higher neighborhood disadvantage predicted worse performance on reversal learning at age 10, but not at age 17, and did not predict differences on other EF tasks.  In Study 3, I examined the effects of early childhood parental nurturance and environmental stimulation, within a low-SES sample, on stress reactivity to a laboratory stressor in late adolescence. Parental nurturance was positively related to cortisol and heart rate reactivity, with those experiencing lower levels of nurturance demonstrating an attenuated cortisol response.  Effects were independent of home quality and other environmental risk factors. Implications of these studies and future directions are discussed.