Gratitude enhances widespread dynamic cooperation and inter-brain synchronization in females

From both social and life perspectives, gratitude is essential for managing social relationships and fostering cooperation. This study investigated the dynamic influence of gratitude on two modalities of cooperative interactions and the associated interpersonal dynamic neural mechanism by integrating a dyadic ecological paradigm with functional near-infrared spectroscopy). Several critical findings emerged: the gratitude group exhibited better cooperative behaviors compared to the joy and neutral groups in both the Prisoner's Dilemma Game (PDG) and the Button-press Game (BPG). The dynamic cooperative behaviors further elucidated that gratitude dynamically facilitates cooperation by boosting inclusivity towards the benefactor's slight defect in the PDG and heightening action coordination in the BPG. Accordingly, higher inter-brain synchronization (IBS) was predominantly observed in the left and right middle frontal gyrus and the right sensorimotor cortex in the gratitude, compared to the joy and neutral groups. Moreover, the gratitude group exhibited increased IBS over time (across blocks) in the left and right middle frontal gyrus and the right superior temporal gyrus. These findings substantiate that gratitude facilitates widespread social cooperation and progressively enhances IBS among individuals. This work advances our understanding of gratitude-induced large-scale cooperative behaviors in societies.