What is Inter-brain Synchrony?
Inter-brain synchrony (or neural synchrony) is the phenomenon where the brain activity of two or more people becomes correlated during social interaction. Their neural rhythms — EEG, HRV — begin to align.
Key Properties
- •Coherence — brain rhythms operate in phase
- •HRV synchronization — heart rate variability aligns between partners
- •Alpha-rhythm coherence — relaxed, attentive states synchronize
- •Bidirectional — both participants influence and are influenced
Why does Inter-brain Synchrony matter?
Inter-brain synchrony matters because it may help explain how people coordinate, communicate, and feel connected. When two people interact, aligned brain activity could reflect shared attention, mutual prediction, or a common understanding of what is happening.
Studies have linked higher synchrony to smoother cooperation, better learning between teachers and students, and closeness between partners or parents and children. The evidence is still limited and debated. Many findings come from small samples, and it is unclear whether synchrony causes better interaction or simply reflects people doing and perceiving the same things.
What affects Inter-brain Synchrony?
In research settings, synchrony tends to rise with face-to-face contact, eye contact, turn-taking in conversation, shared goals, and coordinated movement such as making music together. It generally drops when people work in parallel without interacting or when attention is divided.
Relationship and context may matter too: some studies report stronger synchrony between familiar partners. Because shared stimuli and matched movements can produce similar-looking signals on their own, researchers use control conditions to separate genuine interaction effects from common input. Findings vary across measurement methods and analysis approaches.
In ONDA Life
Part 11 lists "Inter-brain Synchrony" as a target: "the brain rhythms of partners begin to operate in a coherent mode." Its intended markers include "synchronization of Heart Rate Variability (HRV) between partners and Alpha-rhythm brain coherence." ONDA does not record EEG and does not compare two people's signals, so these describe the aim of the practice, not markers the app measures.