The Influence of Shared Attention and Friendship on Emotional Processing: A Behavioral and EEG Hyperscanning Study

Background: Shared attention facilitates interpersonal emotional sharing, yet the neural mechanisms modulated by interpersonal relationships, emotional valence, and visual consistency remain unclear. Methods: This study recruited 39 dyads (22 friend dyads, 17 stranger dyads) who viewed neutral, positive, and negative images under shared or non-shared attention while image consistency between partners was manipulated. Emotional ratings and electroencephalography (EEG) inter-brain synchrony were recorded. Results: Behaviorally, shared attention shifted emotional processing toward positivity, especially in friend dyads. EEG hyperscanning revealed that shared attention was associated with increased beta and theta band inter-brain synchrony in the prefrontal cortex for friends, but decreased synchrony for strangers, and alpha band synchrony decreased with shared attention when viewing consistent images. Conclusions: These findings reveal band-specific neural mechanisms through which shared attention modulates emotion across friendship, offering new insights into emotional regulation in social interactions.