Experiments evaluate the fit of human behaviour to the Shapley-Shubik power index (SSPI), a formula of voter power. Groups of six subjects with differing votes divide a fixed purse by majority rule in online chat rooms. Earnings proxy for measured power. Chat rooms and processes for selecting...

What is the strategic role of membership in an intergovernmental group with unanimity requirements if the group negotiates with an external player in a setting with incomplete information? Being in such a group has a strategic effect compared to negotiating as a standalone player and reduces the...

I explore possible impacts of reciprocal preferences on participation in international environmental agreements. Reciprocal countries condition their willingness to abate on others' abatement. No participation is always stable. A full or majority coalition can be stable, provided that...

The paper analyzes the role of the structure of communication - i.e. who is talking with whom - on the choice of messages, on their credibility and on actual play. We run an experiment in a three-player coordination game with Pareto ranked equilibria, where a pair of agents has a profitable...

International climate negotiations have been troubled by mutual mistrust. At the same time, a hope seems to prevail that once enough countries moved forward, others would follow suit. If the abatement game faced by climate negotiators is a Prisoners' Dilemma, and countries are narrowly...