Exploration of Auditory Statistical Learning, Socioeconomic Status, and Language Outcomes in Bangladeshi Children: A Functional Near-Infrared Spectroscopy Study

Auditory statistical learning, or the ability to detect statistical regularities in continuously presented stimuli, is thought to be one element that underlies language acquisition. Prior studies have uncovered behavioral and neural correlates of statistical learning, yet additional work is needed from low- and middle-income countries to explore whether statistical learning varies across cultures or underlies associations often found between socioeconomic status (SES) and language outcomes. In the present study, we explored the feasibility of using functional near-infrared spectroscopy (fNIRS) to explore auditory statistical learning in Bangladesh, a lower-middle-income country. Participants were 102 2-year-old (M = 25.72 months, SD = 2.07 months) and 125 5-year-old children (M = 62.35 months, SD = 2.46 months) living in a low-income urban neighborhood of Dhaka (average family income of 28,145.13 Bangladeshi Takas or 260.06 U.S. dollars per month). We also collected measures of SES and language outcomes. Brain responses during the statistical learning paradigm could be detected with fNIRS in both two- and 5-year-olds, with 2-year-olds exhibiting a higher response to predictable sequences and 5-year-olds exhibiting higher responses to unpredictable sequences. fNIRS correlates of statistical learning were not related to language outcomes but were associated with SES in the 5-year-old cohort. This study demonstrates the utility of employing fNIRS to study the neural correlates of statistical learning in low- and middle-income countries and the feasibility of expanding the representativeness of the existing literature. These findings also highlight potential areas for inquiry into how SES may relate to individual differences in statistical learning responses. Public Significance Statement Two- and 5-year-old-children living in profound poverty in Dhaka, Bangladesh, showed different brain responses to familiar and novel auditory patterns. These brain responses were not associated with language outcomes in either age group but, for 5-year-olds only, were related to socioeconomic status. These results show the utility of brain imaging techniques in uncovering how children's early environments may relate to auditory processing during different periods of development.