Political games of attack and defence.

Political conflicts often revolve around changing versus defending a . We propose to capture the dynamics between proponents and opponents of political change in terms of an asymmetric game of attack and defence with its equilibrium in mixed strategies. Formal analyses generate predictions about effort expended on revising and protecting the , the form and function of false signalling and cheap talk, how power differences impact conflict intensity and the likelihood of revision. Laboratory experiments on the neurocognitive and hormonal foundations of attack and defence reveal that out-of-equilibrium investments in attack emerge because of non-selfish preferences, limited capacity to compute costs and benefits and optimistic beliefs about the chances of winning from one's rival. We conclude with implications for the likelihood of political change and inertia, and discuss the role of ideology in political games of attack and defence. This article is part of the theme issue 'The political brain: neurocognitive and computational mechanisms'.