Human cooperation is an astonishing phenomenon, as only humans exhibit such immense scale, complexity, and frequency in working together with other people. In this dissertation, I investigate how... Show moreHuman cooperation is an astonishing phenomenon, as only humans exhibit such immense scale, complexity, and frequency in working together with other people. In this dissertation, I investigate how nonverbal communication between two individuals affects cooperative success as well as methodological challenges when examining this topic in laboratory settings. To answer these questions, the dissertation comprises four chapters presenting two theoretical and two methodological studies. In the first two chapters, I demonstrate the beneficial effect of face-to-face interactions on cooperation. I subsequently show that physiological synchrony emerges during social interactions and is positively associated with cooperative success. This finding suggests that physiological synchrony might be an underlying mechanism for the beneficial effect of face contact on cooperation. In the methodological studies, I place the tasks typically used to measure cooperation into the broader context of prosocial behavior. Furthermore, I address the statistical challenges inherent to measuring synchrony between interaction partners. The cardinal point of this dissertation is that interpersonal processes that we are not aware of play a fundamental role in how we behave towards other people. Addressing methodological challenges that come along with studying dyadic interactions will greatly advance our understanding of social phenomena that make us human so unique. Show less
Cooperation forms the basis of our society and becomes increasingly essential during times of globalization. However, despite technological developments people still prefer to meet face-to-face,... Show moreCooperation forms the basis of our society and becomes increasingly essential during times of globalization. However, despite technological developments people still prefer to meet face-to-face, which has been shown to foster cooperation. However, what is still unclear is how this beneficial effect depends on what people know about their interaction partner. To examine this question, 58 dyads played an iterated Prisoner’s Dilemma game, sometimes facing each other, sometimes without face contact. Additionally, explicit feedback regarding their decisions was manipulated between dyads. The results revealed that participants were more cooperative when they saw each other compared to when they could not, and when receiving reliable compared to unreliable or no feedback. Contradicting our hypothesis that participants would rely more on nonverbal communication in the absence of explicit information, we observed that the two sources of information operated independently on cooperative behavior. Interestingly, although individuals mostly relied on explicit information if available, participants still cooperated more after their partner defected with face-to-face contact compared to no face-to-face contact. The results of our study have implications for real-life interactions, suggesting that face-to-face contact has beneficial effects on prosocial behavior even if people cannot verify whether their selfless acts are being reciprocated. Show less
