Learning with Others: Brain Systems and Social Behaviours

Successful learning often emerges through social interaction. What are the neural and behavioural systems that support this process? This ecological, multimodal study combines functional near infrared spectroscopy (fNIRS) hyperscanning with detailed behavioural and physiological measures to investigate the neural mechanisms underlying real-time face-to-face social learning. Twenty-seven teacher–learner dyads engaged in teaching and learning facts about unfamiliar items while we recorded their speech, breathing, head movement, gaze behaviour, and cortical brain activity using fNIRS. Learning was supported by teacher-learner inter-brain synchrony (INS), over regions important for mutual understanding (TPJ) and communicative coordination (PMv). Joint attention and mutual gaze modulated the relationship between INS and learning with opposite effects. To explain this, we propose a dual-process model. When teacher and learner are not yet aligned, learning is supported by informational uptake dynamic, with high joint attention, low INS in regions for mutual understanding (TPJ) and coordination (right PMv), and high INS in language-related areas (left PMv). In contrast, during moments of mutual grounding, learning is supported by high mutual gaze and high INS in systems for mutual understanding (TPJ). These findings suggest that different social behaviours engage distinct patterns of brain-to-brain coupling that support learning through different cognitive dynamics. Cross-brain general linear modelling (xGLM) further revealed asymmetric neural dependencies tied to speaking and teaching roles within the left-hemisphere language network. Crucially, these effects persisted after accounting for nodding, gaze, and breathing, demonstrating that INS reflects genuine social-cognitive alignment rather than mere sensorimotor coupling. Taken together, this study shows that successful learning arises from coordinated brain–body dynamics and positions INS as a marker of mutual prediction during social interaction.