We identify the inefficiencies that arise when negotiation between two parties takes place in the presence of transaction costs. First, for some values of these costs it is efficient to reach an agreement but the unique equilibrium outcome is one in which agreement is never reached. Secondly,...

We study type spaces where a player's type at a state is a conditional probability on the space. We axiomatize these spaces using conditional belief operators, examining three additional axioms of increasing strength. First, introspection, which requires the agent to be unconditionally certain...

Applying unawareness belief structures introduced in Heifetz, Meier, and Schipper (2013a), we develop Bayesian games with unawareness, define equilibrium, and prove existence. We show how equilibria are extended naturally from lower to higher awareness levels and restricted from higher to lower...

This article provides a brief survey of the literature on unawareness and introduces the contributions to the special issue on unawareness in Mathematical Social Sciences. First, we provide a brief overview both about epistemic models of unawareness and models of extensive-form games with...

In this paper, we introduce a notion of epistemic equivalence between hierarchies of conditional beliefs and hierarchies of lexicographic beliefs, thus extending the standard equivalence results of Halpern (2010) and Brandenburger et al. (2007) to an interactive setting, and we show that there...

Human utility embodies a number of seemingly irrational aspects. The leading example in this paper is that utilities often depend on the presence of salient unchosen alternatives. Our focus is to understand <i>why</i> an evolutionary process might optimally lead to such seemingly dysfunctional features...

Social norms of cooperation are studied under several forms of communication. In an experiment, strangers could make public statements before playing a prisoner's dilemma. The interaction was repeated indefinitely, which generated multiple equilibria. Communication could be used as a tool to...

Under what conditions can cooperation be sustained in a network of strangers? Here we study the role of institutions and uncover a new behavioral foundation for the use of monetary systems. In an experiment, anonymous subjects could cooperate or defect in bilateral random encounters. This...

We study individual behavior of students and workers in an experiment where they repeatedly faced with the same cooperative task. The data show that clerical workers differ from college students in overall cooperation rates, strategies adopted, and use of punishment opportunities. Students...

This study reveals the existence of a causal link between the availability of money and an expanded scale of interaction. We constructed an experiment where participants chose the group size, either a low-value partnership or a high-value group of strangers, and then faced an intertemporal...