Beyond bilingual advantages: contexts, mechanisms, and correlates of executive function in bilingual and monolingual children
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At least 20% of the US population is estimated to be bilingual, and there is wide popular and academic interest in the neurocognitive consequences of bilingualism. A controversial body of literature points to “bilingual advantages” in executive function (EF) skills involving attention, inhibitory control, and cognitive flexibility. However, while bilingual advantages are thought to be a result of neuroplasticity, we do not currently understand the specific neural mechanisms shaped in childhood. Further, studies have failed to account for the distinction between “cool,” more purely cognitive, and “hot,” more affective and motivationally relevant EF systems. Lastly, the study of bilingual EF development has been sparse in preschool children, when EF skills are most rapidly developing. The present research compared behavioral, neurocognitive, and demographic correlates of cool (cognitive) and hot (affective) EF, in healthy monolingual and bilingual children with at least 20% exposure to a second language. In Study 1, I examined whether 3.5. - 4.5 year old bilinguals show better and faster conflict inhibition and cognitive flexibility, and neural differences in inhibition, monitoring, and error-processing, in cool and hot contexts. Results showed faster cool inhibition and faster hot cognitive flexibility in bilinguals, accompanied by neural differences in cool error-processing. In Study 2, I examined whether 6-8 year old bilinguals show better and faster interference control in cool and hot tasks, and neural difference in inhibition, monitoring, error-processing, and response preparation. Results showed no performance or neural differences between groups. In Study 3, I examined whether 6-8 year old bilinguals show better and faster flexible switching in linguistic and non-linguistic contexts, and better word-object mapping in an unfamiliar language. Results showed no performance differences between groups. In addition to the behavioral and neural findings, all three studies revealed group differences in demographic and cognitive correlates of EF. Together, results suggest that bilingual advantages may be most relevant in preschoolers, susceptible to motivational context, supported by error-awareness mechanisms, and unrelated to motor processing. Future studies of error-processing and response-preparation mechanisms can shed light on how bilingualism shapes brain function, and can elucidate group differences in the behind-the-scenes of inhibitory and switching processes.