Parallel contributions of socioeconomic status and bilingual experiences on executive function and the brain in young children

Executive functions (EF) are foundational for children's cognitive, socio-emotional, and academic outcomes, and socioeconomic status (SES) is consistently associated with disparities in children's EF performance and EF-related brain function. While bilingual children sometimes exhibit an "advantage" on certain EF tasks compared to their monolingual counterparts, it is unknown whether early bilingual experience may buffer the effects of low SES on EF in either brain or behavior. A SES-diverse sample (n = 80) of monolingual and bilingual children (4-6 years old) completed behavioral measures of EF and functional magnetic resonance imaging (fMRI) while engaging in a dichotic listening auditory selective attention task. Bilingualism was measured both by subjective parental report of children's language knowledge, as well as objective annotations of two daylong recordings of children's naturalistic language exposure. Selective auditory attention (vs. normal binaural speech) elicited activation in canonical attention/EF (posterior cingulate, precuneus, and cuneus) and language (posterior temporal gyrus and inferior frontal gyrus) regions. While there was no evidence of a protective effect of bilingualism, there were independent main effects of both SES and bilingual experience. Specifically, higher SES was associated with better EF performance and greater activation in bilateral precunei, independent of mono/bilingual status. While parent-reported bilingual knowledge was not associated with either brain or behavior independent of SES, children who had more balanced bilingual exposure at home exhibited better EF performance than those with more unbalanced or monolingual exposure in either language. Findings contribute to our understanding of the independent influences of specific experiences on children's EF development across contexts.