This paper studies the extent to which diffusion approximations provide a reliable guide to equilibrium selection results in finite games. It is shown that they do for a class of finite games with weak learning provided that limits are taken in a certain order. The paper also shows that making...

We exploit a unique opportunity to study how a large population of players in the field learn to play a novel game with a complicated and non-intuitive mixed strategy equilibrium.  We argue that standard models of belief-based learning and reinforcement learning are unable to explain the data,...

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...

We study evolutionary dynamics in assignment games where many agents interact anonymously at virtually no cost.  The process is decentralized, very little information is available and trade takes place at many different prices simultaneously.  We propose a completely uncoupled learning process...

We study decentralized learning dynamics for the classic assignment game with transferable utility.  At random points in time firms and workers match, break up, and re-match in the sesarch for better opportunities.  We propose a simple learning process in which players have no knowledge about...

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...

A long-standing open question raised in the seminal paper of Kalai and Lehrer (1993) is whether or not the play of a repeated game, in the rational learning model introduced there, must eventually resemble play of exact equilibria, and not just play of approximate equilibria as demonstrated...

Stochastic learning models provide sharp predictions about equilibrium selection when the noise level of the learning process is taken to zero.  The difficulty is that, when the noise is extremely small, it can take an extremely long time for a large population to reach the stochastically...

A rational player will never play a strictly dominated strategy. It might be tempting therefore to eliminate such strategies from any subsequent analysis. However, if equilibrium selection is an issue it may be wrong to do so. In models of adaptive learning with state-independence mutations,...

We examine some of the factors that might influence the quality of information produced in discussion groups on the internet, such as USENET and the WELL. In particular, we look at the impact of various different pricing structures, and compare regimes in which anonymity is enforced with regimes...