Interactive feedback in persuader-persuadee interaction enhances Persuasion: An fNIRS hyperscanning study

Persuasion is a fundamental social skill in humans, serving as a crucial foundation for information propagation and social influence. Existing research has predominantly focused on a mechanical understanding of persuasive content, overlooking the interactive nature of persuasion. The current study investigates the effects of interactive feedback on interpersonal persuasion and its underlying neurocognitive mechanisms, utilizing a dyadic persuasion paradigm with high ecological validity in combination with functional near-infrared spectroscopy (fNIRS). Participants visited the laboratory on two occasion to complete all tasks: the item selection task (first visit) and the fNIRS hyperscanning dyadic persuasion task (second visit). In the item selection task, participants attended the laboratory individually, where they were instructed to read the Arctic survival scenario, select the three most critical items from a list of 15 items, and rank them according to their significance for survival. The fNIRS hyperscanning task consisted of two phase: a no-discussion phase (no feedback) and a discussion phase (feedback). Additionally, to eliminate the confounding effects of interactive feedback on persuasion that might arise from repeated information processing (e.g., repeated exposure to persuasive content enhancing persuasion) or interpersonal factors (e.g., intimacy, interpersonal distance), two control conditions were included. In control condition 1, both task parts were identical. In control condition 2, phase two involved independent thinking phase, where participants were asked to reflect independently on the other person’s opinions and complete the item selection task. This study primarily focuses on the prefrontal cortex and the left temporoparietal regions. The behavioral results indicate that, compared to the no interactive feedback condition, interactive feedback enhanced both persuasion outcomes and perceived persuasiveness. In neural activity, our results showed that interactive feedback strengthened brain-to-brain synchrony between the persuader and the persuadee in the right frontal cortex and left temporoparietal regions, with this synchrony positively predicting persuasion outcomes. Granger causality results further revealed the directional characteristics of the brain-to-brain synchrony, shedding light on the interaction patterns between the persuader and the persuadee during persuasive interaction. Regarding the use of persuasion strategies, compared to supportive strategy, persuaders in the interactive feedback phase more frequently employed refutational strategies. Furthermore, brain-to-brain synchrony under the refutational strategy was significantly higher than under the supportive strategy. Moreover, brain-to-brain synchrony gradually increased after, rather than before, the refutational strategy was employed. This finding confirms that refutational strategies are crucial for promoting persuasion, with the 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, brain-to-brain synchrony serves as a critical neural mechanisms that drives the persuader and persuadee to reach cognitive consensus, thereby facilitating subsequent changes in the persuadee's attitudes and behaviors. The current study provides a novel perspective on how interactive feedback enhances interpersonal persuasion and contributes to a deeper understanding of the complex and authentic persuasion processes through interpersonal neuroscience.