Interconnections among financial institutions create potential channels for contagion and amplification of shocks to the financial system.  We propose precise definitions of these concepts and analyze their magnitude.  Contagion occurs when a shock to the assets of a single firm causes other...

The diffusion of an innovation can be represented by a process in which agents choose perturbed best responses to what their neighbors are currently doing.  Diffusion is said to be fast if the expected waiting time until the innovation spreads widely is bounded above independently of the size...

Social norms are patterns of behavior that are self-enforcing at the group level: everyone wants to conform when they expect everyone else to conform.  There are multiple mechanisms that sustain social norms, including a desire to coordinate, fear of being sanctioned, signaling membership in...

In recent years bonuses tied to performance have become commonplace in banks and other financial institutions; indeed they now constitute a major part of employee compensation.  The practice was originally justified by academic work on principal-agent contracts, which argued that performance...

A foundational assumption in economics is that people are rational -- they choose optimal plans of action given their predictions about future states of the world In games of strategy this means that each players?strategy should be optimal given his or her prediction of the opponents?strategies...

A conventional contract is a contract that each side of a bargain expects the other side to insist on, because it is standard and customary under the circumstances. The author considers a process of convention formation in which agents expectations evolve through repeated interactions in a...

We consider processes in which new technologies and forms of behavior are transmitted through social and geographic networks Agents adopt behaviors based on a combination of their inherent payoff and their local popularity (the number of neighbors who have adopted them) subject to some random...

The author shows how a group of individuals can learn to play a coordination game without any common knowledge and with only a small amount of rationality. The game is repeated many times by different players. Each player chooses an optimal reply based on incomplete information about what other...