Racial minorities, particularly non-Hispanic Blacks in the US, experience weaker effects of family socioeconomic position (SEP) on tangible outcomes, a pattern called Minorities' Diminished Returns (MDRs). These MDRs are frequently shown for the effects of family SEP on immigrant adolescents' school performance. As a result of these MDRs, immigrant adolescents from high SEP families show worse than expected cognitive outcomes, including but not limited to poor school performance. However, the existing knowledge is minimal about the role of executive function in explaining diminished returns of family SEP on adolescents' outcomes. To investigate racial differences in the effects of parental human capital on adolescents' executive function, we compared non-Hispanic White non-immigrant and immigrant adolescents for the effect of parental human capital on adolescents' executive function. This was a cross-sectional analysis that included 2,723 non-twin non-Hispanic White adolescents from the Adolescent Brain Cognitive Development (ABCD) study. The independent variable was parental human capital (parental educational attainment), treated as a continuous measure with a higher score reflecting higher subjective socioeconomic status. The primary outcome was adolescents' executive function measured by the stop-signal task (SST). Age, sex, parental marital status, parental employment, family income, and financial difficulties. Immigration status was the effect modifier. Overall, high parental human capital was associated with higher task-based executive function. Immigration status showed statistically significant interactions with parental human capital on adolescents' executive function outcomes. This interaction term suggested that high parental human capital has a smaller effect on increasing immigrants' executive function compared to non-immigrant adolescents. The boosting effect of parental human capital on executive function is diminished for immigrants compared to non-immigrant adolescents. To minimize the inequalities in executive function-related outcomes such as school performance, we need to address the diminishing returns of existing resources for immigrants. Not only should we equalize groups based on their SEP but also equalize the marginal returns of their existing SEP. Such efforts require public policies that aim for equal processes. As such, social policies should address structural and societal barriers such as xenophobia, segregation, racism, and discrimination that hinder immigrant families' ability to effectively utilize their resources. In a fair society, immigrant and non-immigrant families should be equally able to leverage their SEP resources and turn them into tangible outcomes.
Keywords: Immigrants; Immigration; adolescents; brain; cognition; executive function; health equality; health equity; socioeconomic status.