How a speaker herds the audience: Multi-brain neural convergence over time during naturalistic storytelling

Storytelling--an ancient way for humans to share individual experiences with others--has been found to induce neural synchronization among listeners. In our exploration of the dynamic fluctuations in listener-listener (LL) coupling throughout stories, we uncover a significant correlation between LL and lag-speaker-listener (lag-SL) couplings over time. Using the analogy of neural pattern (dis)similarity as distances between participants, we term this phenomenon the "herding effect": like a shepherd guiding a group of sheep, the more closely listeners follow the speakers prior brain activity patterns (higher lag-SL similarity), the more tightly they cluster together (higher LL similarity). This herding effect is particularly pronounced in brain regions where neural synchronization among listeners tracks with behavioral ratings of narrative engagement, highlighting the mediating role of narrative content in the observed multi-brain neural coupling dynamics. By integrating LL and SL neural couplings, this study illustrates how unfolding stories shape a dynamic multi-brain functional network and how the configuration of this network may be associated with moment-by-moment efficacy of communication. Significance StatementDifferent stories have been found to evoke distinct brain activation patterns in the audience. This study delves into how the storyteller guides the audience through the multi-dimensional space of brain states, reflected in a series of shared activation patterns. We reveal that the listeners follow along the trajectory outlined by the speakers brain activity moments before, forming a tighter cluster at the more engaging moments of the story. This phenomenon is localized to high-level cortical areas supporting event representation. Our investigation illustrates how storytelling dynamically sculpts multi-brain neural dynamics in both the listeners and the speaker, shedding light on the potential association between the configuration of this network and communication efficacy.