Investigating language entropy as a predictor of cognitive control in bilinguals using pupillometry

Effects of bilingualism on cognitive control have regularly been found in children and older adults, but are much less consistently found in young adults [1]. Three reasons for these inconsistent findings have been proposed. First, cognitive control peaks in young adulthood resulting in less pronounced individual differences, especially in reaction times [2]. Second, bilingualism is often operationalised as a binary variable, while no two bilinguals have exactly the same language experience. This potentially masks individual differences [3]. Third, recent work has stressed that different communicative contexts place varying cognitive demands on the speaker and should be taken into account in research effects of bilingualism on cognitive control [4].
The present study investigates these possible explanations. The cognitive control of young adults with varying language backgrounds (N=45) was measured using a colour-shape switching task. To address the first reason, behavioural data of the switching task was supplemented with pupillometric data to gauge a sensitive online measure of cognitive effort. To address reasons two and three, we administered an extensive background questionnaire and computed language entropy scores. Language entropy has recently been put forward as a quantitative measure of bilinguals’ language use across different communicative contexts [5].
Our ongoing analyses will address whether language entropy modulates cognitive control and pupil dilation in a varied group of bilinguals. If more balanced use per context positively affects cognitive control, we expect to find faster reaction times and smaller pupil dilation for switch trials in more balanced bilinguals as compared to bilinguals who use their languages in a more compartmentalised way. Furthermore, if the pupillometric data uncovers subtle differences in cognitive effort as a function of language use per context, then these data would stress the usefulness of online measures like pupillometry to investigate effects of bilingualism on cognitive control in young adults.

References
[1] Antoniou, M. (2019). The advantages of bilingualism debate. Annual Review of Linguistics, 5(1), 395–415. https://doi.org/10.1146/annurev-linguistics-011718-011820
[2] Park, D. C., Lautenschlager, G., Hedden, T., Davidson, N. S., Smith, A. D., & Smith, P. K. (2002). Models of visuospatial and verbal memory across the adult life span. Psychology and Aging, 17(2), 299–320. https://doi.org/10.1037//0882-7974.17.2.299
[3] Luk, G., & Bialystok, E. (2013). Bilingualism is not a categorical variable: interaction between language proficiency and usage. Journal of Cognitive Psychology, 25(5), 605–621. https://doi.org/10.1080/20445911.2013.795574