Bilingual Mothers' Neural Synchrony with Children Remains Stable in English, Study Finds

Interbrain synchrony, defined as the alignment of neural activities between individuals during social engagement, is recognized as fundamental for fostering emotional rapport and optimizing communication efficacy within the parent-child dyad. New research provisionally accepted by Frontiers in Cognition in late 2025, spearheaded by the University of Nottingham, provides evidence that this critical neural connection remains robust in bilingual families even when the mother communicates in her acquired second language, English.

This finding directly addresses concerns that using a non-native language might introduce a barrier to deep emotional closeness in multilingual households. The investigation, led by Dr. Efstratia Papoutselou, a Research Fellow at the University of Nottingham, with senior author Professor Douglas Hartley, involved 15 bilingual families residing in the UK. The mothers demonstrated advanced English proficiency, meeting Common European Framework of Reference for Languages (CEFR) C1 or C2 standards, and their children were between three and four years old.

Researchers employed functional near-infrared spectroscopy (fNIRS) hyperscanning to capture the simultaneous brain activity of the mother-child pairs during structured play scenarios. This methodology assesses real-time neural coupling, which is often strongest in the prefrontal cortex (PFC), a region integral to higher-order functions such as decision-making and emotional processing. The experimental design included collaborative play in the mother's native language, collaborative play in English, and independent play.

Analysis of the fNIRS data revealed significant interbrain synchrony, with the strongest alignment consistently observed within the PFC. Crucially, the magnitude of this neural synchrony was found to be statistically equivalent between the native language interactions and those conducted in English. Professor Hartley emphasized that the neural bond essential for attachment is fully preserved irrespective of the language used.

These outcomes suggest that high proficiency in a second language is sufficient to maintain this vital brain-to-brain connection, supporting the neural substrates necessary for healthy social development. This 2026 discovery effectively dispels prior assumptions that non-native language use might compromise the foundational neural mechanisms underpinning parent-child attachment and communication.