Strategic voting under proportional representation and coalition governments: a laboratory experiment

"We investigate whether the theory of strategic voting can explain voting behavior in a fairly common type of political system, multi-party systems with proportional representation, minimum vote thresholds, and coalition governments. In this paper, we develop a formal (computational) strategic voting game and show in a simulation that the model produces election scenarios and outcomes with desirable characteristics as well as different opportunities for strategic voting. We then test the decision-theoretic model in a laboratory experiment, taking into account both sophisticated and heuristic decision strategies. Participants with a purely instrumental (financial) motivation voted in a series of 25 independent elections. The availability of polls and coalition signals by parties was manipulated. The results show that voters are frequently able to make optimal or strategic vote decisions, but that voters also rely on simple decision heuristics and are highly susceptible to coalition signals by parties." (author's abstract