Summary: Researchers found that eye contact acts as an intentional switch that synchronizes brainwaves between infants and adult speakers, directly supporting selective language learning.
A cross-cultural study recorded brain activity in 8- to 10-month-old infants with electroencephalography (EEG) while they listened to novel, nonsense languages. The research team discovered that infants learned a new language only when they had clear, unobstructed visual access to the speaker’s eyes.
Inter-brain neural synchrony between the infant and the speaker predicted language learning outcomes more reliably than the infant’s individual brain activity alone, demonstrating that social signals actively gate cognitive processing in the infant brain.
Key Facts
- Neural synchronization mechanism: Direct eye contact triggers inter-brain synchrony between an adult speaker and an infant, creating a prioritized cognitive channel for processing incoming linguistic information.
- Visual gating experiment: Forty-two infants (8–10 months old) in Cambridge and Singapore were exposed to three artificial languages paired with the same speaker wearing clear glasses, partially shaded glasses, or dark opaque glasses.
- Selective learning outcomes: Although infants spent similar amounts of time looking at the screen in all conditions, they learned vocabulary only when the speaker’s eyes were fully visible.
- Inter-brain synchrony over individual activity: Neural alignment between speaker and infant was a stronger predictor of language retention than the infant’s isolated EEG activity.
- Cross-cultural universality: Results were consistent across UK and Singapore cohorts, indicating that visual social gating is a widespread mechanism in early human neurodevelopment.
Source: University of Cambridge
Overview: Infants use eye contact with speakers to determine what to attend to and to synchronize their brainwaves with the speaker, which supports language learning, according to scientists working in Cambridge and Singapore.
Infants live in a world full of competing sensory inputs—sights, sounds and voices—all vying for attention. To decide what is worth learning, they rely on social cues such as eye contact, infant-directed speech and name-calling. Until now, the neural mechanism by which these cues promote learning has been poorly understood.
Professor Victoria Leong and colleagues at the University of Cambridge and Nanyang Technological University (NTU), Singapore, had previously observed that making eye contact causes brainwaves in adults and infants to align. Their new study, published in Nature Communications, shows that eye contact functions as a switch: it synchronizes the infant’s brain with the speaker’s and thereby signals which information should be encoded.
In the experiment, infants in both countries listened to three artificial languages composed of repeated triplets of syllables. Each language was paired with the same female speaker shown on a screen wearing either clear glasses (full eye visibility), partially shaded glasses (partial visibility) or dark glasses (no visibility). While infants were familiarized with these languages, researchers recorded the infants’ EEG and used previously recorded EEG data from the speaker’s video recordings to measure speaker-to-infant neural coupling.
To assess learning, the speaker later presented phrases from the familiarized languages alongside novel nonsense words. Infants who had learned a language were expected to differentiate and show predictable looking behavior toward unfamiliar language samples. The study included 42 infants across the UK and Singapore.
Professor Leong explained that infants were selective learners: they heard all three languages but only learned the one presented with clear eye contact. The researchers found that when infants were successfully learning, their brain rhythms became synchronized with the speaker’s. Importantly, this synchrony was a stronger indicator of learning than any measure of the infant’s brain activity alone. Crucially, synchrony occurred only when the infant could clearly see the speaker’s eyes.
Although infants looked at the screen for similar durations regardless of eye visibility, mere visual attention did not guarantee learning. As Dr Kaili Clackson noted, when eye contact was absent the information “washed over” infants; attentive-looking without social engagement did not lead to cognitive processing or language acquisition.
The pattern held across both Cambridge and Singapore samples, supporting the idea that visual social gating is not confined to one culture. In Singapore, infants tended to look slightly longer at the speaker, possibly due to the speaker’s ethnicity being less familiar, but this did not change whether learning occurred.
Eye contact is a prominent ostensive signal that communicates an adult’s intention to teach. Other cues—such as smiling, pointing or using the infant’s name—can convey similar instructional intent and may be especially important in cultures where direct eye contact is less common or discouraged.
Dr Clackson emphasized that these social cues are powerful: when new information is prefaced by eye contact or name-calling, infants interpret it as important and worth encoding.
The research team hopes the results will encourage caregivers to engage intentionally with infants. Professor Leong advised that parents put away distractions and make eye contact when teaching or giving instructions, since these signals convey intentionality and increase the likelihood that the child will learn.
Funding: The research was supported by A*STAR and the Ministry of Education, Singapore.
Key Questions Answered:
A: Inter-brain synchrony functions as a biological filter that aligns the infant’s neural firing with the instructor’s. This alignment signals that the incoming acoustic and visual information is intentional and relevant, increasing the likelihood that it will be encoded into long-term memory.
A: No. Infants looked at the video screens for comparable lengths of time regardless of whether the speaker’s eyes were visible. However, without direct eye contact, that visual attention did not translate into the neural processing needed for language acquisition.
A: Passive exposure to language—such as background audio, videos without social engagement, or distracted caregivers using mobile devices—does not reliably trigger inter-brain synchrony. Direct, face-to-face engagement that includes eye contact, name-calling and expressive social cues is more effective at activating the neural mechanisms that support early learning.
Editorial Notes:
- Article edited by a Neuroscience News editor.
- Journal paper reviewed in full by editorial staff.
- Additional context provided by the news team.
About this neurodevelopment and language research news
Author: Craig Brierley
Source: University of Cambridge
Contact: Craig Brierley – University of Cambridge
Image: Image credited to Neuroscience News
Original Research: Open access. “Unidirectional adult-to-infant neural coupling mediates infants’ selection of socially-relevant stimuli for learning across cultures” by Wei Zhang (张维), Kaili Clackson, Stanimira Georgieva, Lorena Santamaria, Vanessa Reindl, Valdas Noreika, Nicholas Darby, Vaka Valsdóttir, Priyadharshini Santhanakrishnan & Victoria Leong. Nature Communications. DOI: 10.1038/s41467-026-75831-x
Abstract
Unidirectional adult-to-infant neural coupling mediates infants’ selection of socially-relevant stimuli for learning across cultures
Infants have robust learning abilities but limited neural resources, so they must selectively allocate attention to the most relevant information in social contexts. Adults mark valuable content using ostensive signals like eye contact, but the neural mechanisms underlying this social gating have remained unclear.
This study demonstrates that in infants from the UK and Singapore, unidirectional neural coupling from adult speaker to infant listener mediates the selection of socially relevant information. Speaker-to-listener coupling is modulated by the speaker’s eye contact and predicts selective learning of an artificial language when full eye contact is present compared with partial or no eye contact.
Speaker-to-listener neural coupling better predicts selective learning than the infant’s own neural activity, suggesting this measure captures how social signals influence early cognition and provides insight into the decision processes that guide social learning in infancy.