Persuasion is a fundamental social skill in humans, essential for information propagation and the social influence. Existing research has primarily focused on the aspects of persuasive content, neglecting the interactive dynamics inherent to persuasion. The present study complemented by functional near-infrared spectroscopy (fNIRS) to examines the effects of interactive feedback on interpersonal persuasion and its underlying neurocognitive mechanisms, employing a dyadic persuasion paradigm with high ecological validity. Behavioral results indicate that, relative to the no-interactive-feedback condition, interactive feedback condition enhanced both persuasion outcomes and perceived persuasiveness. In terms of neural activity, results revealed that interactive feedback enhanced brain-to-brain synchrony between the persuader and persuadee in the right frontal cortex and left temporoparietal regions, with this synchrony positively predicting persuasion outcomes. Granger causality further elucidated the directional characteristics of brain-to-brain synchrony, offering insights into the interaction patterns between the persuader and persuadee during the persuasive process. Regarding the employ of persuasion strategies, persuaders in the interactive feedback condition employed refutational strategies more frequently than supportive strategies. Moreover, brain-to-brain synchrony during the refutational strategy was significantly higher than during the supportive strategy. Furthermore, brain-to-brain synchrony gradually increased following, rather than preceding, the employment of the refutational strategy. This finding underscores the importance of refutational strategies in enhancing persuasion, brain-to-brain synchrony between the persuader’s left superior temporal gyrus and the persuadee’s right frontal gyrus effectively tracking and identifying the use of this strategy. In summary, the present study offers a novel perspective on how interactive feedback enhances interpersonal persuasion, contributing to a deeper understanding of the complicate and authentic processes of persuasion through interpersonal neuroscience.
