In Search of Stars: Network Formation among Heterogeneous Agents

This paper reports results from a laboratory experiment on network formation among heterogeneous agents. The experimental design extends the Bala-Goyal (2000) model of network formation with decay and two-way flow of benefits by allowing for agents with lower linking costs or higher benefits to others. Furthermore, agents’ types may be common knowledge or private information. In all treatments, the (efficient) equilibrium network has a “star” structure. With homogeneous agents, equilibrium predictions fail completely. In contrast, with heterogeneous agents stars frequently occur, often with the high-value or low-cost agent in the center. Stars are not born but rather develop: with a high-value agent, the network’s centrality, stability, and efficiency all increase over time. Probit estimations based on best-response behaviour and other-regarding preferences are used to analyze individual linking behavior. Our results suggest that heterogeneity is a major determinant for the predominance of star-like structures in real-life social networks.Network Formation, Experiment, Heterogeneity, Private Information

Focal points revisited: team reasoning, the principle of insufficient reason and cognitive hierarchy theory

It is well-established that people can coordinate their behaviour on focal points in games with multiple equilibria, but it is not firmly established how. Much coordination game data might be explained by team reasoning, a departure from individualistic choice theory. However, a less exotic explanation is also available based on best-responding to uniform randomisation. We test these two accounts experimentally, using novel games which distinguish their predictions. The results are inconsistent with best-responding to randomisation but consistent with team reasoning as the modal behaviour, though there is also unexplained heterogeneity. Increasing the difficulty of the coordination tasks produces some behaviour suggestive of response to randomisation, but this is a minor feature of the data