Charness and Dufwenberg (2006) find that promises increase cooperation and suggest that the behavior of subjects in … observed effects regarding the impact of communication are due to internal factors and not due to an outside bystander …

We examine experimentally the impact of communication on trust and cooperation. Our design admits observation of … avoid guilt, as can be modeled using psychological game theory. When players exhibit such guilt aversion, communication may …

Under what conditions can cooperation be sustained in a network of strangers? Here we study the role of institutions … possible, including full intertemporal cooperation supported by a social norm based on community punishment of defectors. We … coordination on intertemporal cooperation in ways that networks of strangers were unable to achieve through social norms. …