Neural Rhythms of Cooperation : Exploring How Our Brains Play Together

Abstract

Cooperation is a cornerstone of human interaction. Extensive research across the human sciences suggests that human evolutionary success is not merely driven by general intelligence but rather by advanced social coordination abilities. At the heart of these abilities lies collective intentionality, enabling individuals to align their actions toward shared goals and shaping the foundations of social organization. Social neuroscience provides an interdisciplinary framework to examine the neural mechanisms supporting cooperative behavior. This dissertation adopts a process perspective, emphasizing collaborative role taking as a fundamental organizing principle of human cooperation. For this purpose, we developed a dyadic Pacman Game, designed to create a naturalistic yet experimentally controlled social environment by systematically modifying game rules. In this game, players work together to navigate a Pacman through a maze using an agreed-upon coding system based on pictorial cues. Each game move requires two sequential turns, with players alternating between the roles of sender and receiver of two symbolic picture cues. Across three studies, we examined whether neural markers well-established in cognitive and affective neuroscience could reliably track collaborative role taking during gameplay. The first study introduced the Pacman Game as a novel process-oriented experimental paradigm. Participants played the game in dyads while undergoing simultaneous high-density EEG recording. We explored whether event-related potentials (ERPs) could serve as real-time neural indicators of role taking during collaboration. Our findings revealed that larger P3 amplitudes reflected higher informational value for receivers compared to senders of picture cues. Additionally, a distinct late positivity emerged, differentiating whether the receiver’s role was tied to cognitively demanding decision-making or affectively significant action monitoring. Notably, similar effects were observed when participants played with a computerized game partner, suggesting that experimental games may motivate humans to similarly cooperate with an artificial agent. The second study expanded upon the ERP analysis by incorporating spectral analysis to examine induced (non-phase-locked) oscillatory activity linked to collaborative role-taking. We observed distinct changes in alpha to lower beta power associated with player roles, with a pronounced power decrease when receiving compared to sending picture cues. This effect was more pronounced when the receiver role involved heightened cognitive and semantic processing demands. Again, effects were similar when participants played the Pacman Game with human or computer partners. Importantly, we replicated key ERP findings, including a larger P3 component for receivers compared to senders and a late positivity indexing the cognitive demands of specific player roles. The third study addressed the idea that shared goals often carry different importance for the collaborators. To test this, we integrated a monetary gamble into the Pacman Game to systematically influence players’ personal motivation. Our findings showed that enriching shared goals with personal rewards elicited neural signatures of reward processing including positive fronto-central ERP components (RewP, P3, LPP) and induced power increases in delta to theta band oscillations. Furthermore, the study replicated the ERP and oscillatory effects from the previous studies, reinforcing the robustness of our findings. Overall, these studies reveal how dynamic shifts in collaborative roles are systematically reflected in ERP and oscillatory brain activity during cooperative tasks, providing neural insights into the mechanisms of joint action and coordination. The Pacman Game exemplifies the potential of process-oriented experimental paradigms for studying the psychological foundations underlying cooperative behavior. By bridging the gap between highly controlled laboratory studies and real-world social interactions, such games offer a promising avenue for future research in social neuroscience.