Consensus Seeking: How Juror Exclusion Shapes Strategic Incentives in the Borda Count

Countries that elect their policy-makers by means of Plurality Voting tend to have a two-party system. This observation can be explained by the strategic behavior of voters. This article derives two broad classes of voting procedures under which strategic voting behavior induces a two-party system under standard assumptions on voter preferences. One class consists of the voting procedures with unique top-score, i.e., under which a voter can cast a top-score vote for only one candidate (e.g., Plurality Voting, Borda Count). The other class consists of the voting procedures that permit truncated ballots, i.e., under which voters do not have to cast all their votes (e.g., Approval Voting). This analysis suggests that the key for strategic voting behavior to induce a two-party system is that voters can always cast a different score for the two candidates they rank first and second on their ballots.

The Two-Party System under Alternative Voting Procedures

This article presents experiments that analyze the strategic behavior of voters under three voting systems: plurality rule, approval voting, and the Borda count. Applying a level- k reasoning model approach, strategic behavior is found to be significantly different under each treatment (voting system). Plurality rule leads voters to play in the most sophisticated (i.e. best response), but not necessarily insincere, manner. Thus, this voting system displays at the same time the highest incidence of best responses and of sincere votes. The opposite holds for the Borda count games, where voters depart from their sincere strategy the most, without playing the best response strategy. Approval voting shows intermediate levels of sophistication and sincere behavior.

Uncertainty aversion in game theory: Experimental evidence

Many of the small island democracies of the South Pacific are natural laboratories for constitutional and electoral experimentation, but have tended to be ignored by comparative political science research. This article examines one apparently unknown case of electoral innovation from the region: the use of Borda count voting procedures for elections in the Pacific Island states of Nauru and Kiribati. It introduces the basic concept of the Borda count and its relation to other electoral systems, and surveys arguments about the virtues and drawbacks of Borda count electoral systems. It then discusses in some detail the way that the Borda count is used for elections in Nauru and Kiribati, including the political impact of the system, and empirical examples of different types of strategic behaviour at work. It concludes by examining the broader significance of these cases for comparative studies of democracy, elections, social choice, and voting theory.

Borda Count is one of the earliest and most important voting rules. Going far beyond voting, we summarize recent advances related to Borda in computational social choice and, more generally, in collective decision making. We first present a variety of well known attacks modeling strategic behavior in voting—including manipulation, control, and bribery—and discuss how resistant Borda is to them in terms of computational complexity. We then describe how Borda can be used to maximize social welfare when indivisible goods are to be allocated to agents with ordinal preferences. Finally, we illustrate the use of Borda in forming coalitions of players in a certain type of hedonic game. All these approaches are central to applications in artificial intelligence.

Strategic behavior in public good games: when partners drift apart

This paper presents an experiment that evaluates the effect of financial incentives and complexity in political science voting experiments. To evaluate the effect of complexity we adopt a level-k reasoning model concept. This model by Nagel [1] postulates that players might be of different types, each corresponding to the level of reasoning in which they engage. Furthermore, to postulate the effect of financial incentives on subjects’ choice, we used the Quantal Response Equilibrium (QRE) concept. In a QRE, players’ decisions are noisy, with the probability of playing a given strategy increasing in its expected payoff. Hence, the choice probability is a function of the magnitude of the financial incentives. Our results show that low complexity promotes the highest degree of level-k strategic reasoning in every payment treatment. Standard financial incentives are enough to induce equilibrium behavior, and the marginal effect of extra incentives on equilibrium behavior seems to be negligible. High complexity, instead, decreases the rate of convergence to equilibrium play. With a sufficiently high complexity, increasing payoff amounts does promote more strategic behavior in a significant manner. Our results show with complex voting games, higher financial incentives are required for the subjects to exert the effort needed to complete the task.

Plurality voting is perhaps the most commonly used way to aggregate the preferences of multiple voters. The purpose of this paper is to provide a comprehensive study of people's voting behaviour in various online settings under the Plurality rule. Our empirical methodology consisted of a voting game in which participants vote for a single candidate out of a given set.We implemented voting games that replicate two common real-world voting scenarios: In the first, a single voter votes once after seeing a large pre-election poll. In the second game, several voters play simultaneously, and change their vote as the game progresses, as in small committees. The winning candidate in each game (and hence the subject's payment) is determined using the plurality rule. For each of these settings we generated hundreds of game instances, varying conditions such as the number of voters and their preferences.We show that people can be classified into at least three groups, two of which are not engaged in any strategic behavior. The third and largest group tends to select the natural default action when there is no clear strategic alternative. When an active strategic decision can be made that improves their immediate payoff, people usually choose that strategic alternative. Our study has insight for multi-agent system designers in uncovering patterns that provide reasonable predictions of voters' behaviors, which may facilitate the design of agents that support people or act autonomously in voting systems.

It is common in multiagent systems to make a distinction between "strategic" behavior and other forms of intentional but "nonstrategic" behavior: typically, that strategic agents model other agents while nonstrategic agents do not. However, a crisp boundary between these concepts has proven elusive. This problem is pervasive throughout the game theoretic literature on bounded rationality and particularly critical in parts of the behavioral game theory literature that make an explicit distinction between the behavior of "nonstrategic" level-0 agents and "strategic" higher-level agents (e.g., the level-k and cognitive hierarchy models). Overall, work discussing bounded rationality rarely gives clear guidance on how the rationality of nonstrategic agents must be bounded, instead typically just singling out specific decision rules and informally asserting them to be nonstrategic (e.g., truthfully revealing private information; randomizing uniformly). In this work, we propose a new, formal characterization of nonstrategic behavior. Our main contribution is to show that it satisfies two properties: (1) it is general enough to capture all purportedly "nonstrategic" decision rules of which we are aware in the behavioral game theory literature; (2) behavior that obeys our characterization is distinct from strategic behavior in a precise sense.

Anthropomorphization of artificial agents leads to fair and strategic, but not altruistic behavior

The Condorcet Jury Theorem justifies the wisdom of crowds and lays the foundations of the ideology of the democratic regime. However, the Jury Theorem and most of its extensions focus on two alternatives and none of them quantitatively evaluate the effect of agents’ strategic behavior on the mechanism’s truth-revealing power. We initiate a research agenda of quantitatively extend- ing the Jury Theorem with strategic agents by characterizing the price of anarchy (PoA) and the price of stability (PoS) of the common interest Bayesian voting games for three classes of mechanisms: plurality, MAPs, and the mechanisms that satisfy anonymity, neutrality, and strategy-proofness (w.r.t. a set of natural probabil- ity models). We show that while plurality and MAPs have better best-case truth-revealing power (lower PoS), the third class of mechanisms are more robust against agents’ strategic behavior (lower PoA).

We report the results of an experiment in which subjects play games against changing opponents. In one treatment, “senders” send “receivers” messages indicating intended actions in that round, and receivers observe senders' previous-round actions (when matched with another receiver). In another treatment, the receiver additionally observes the sender's previous-round message to the previous opponent, enabling him to determine whether the sender had lied. We find that allowing multiple signals leads to better outcomes when signals are aligned (all pointing to the same action), but worse outcomes when signals are crossed. Also, senders' signals tend to be truthful, though the degree of truthfulness depends on the game and treatment, and receivers' behaviour combines elements of pay-off maximization and reciprocity. Copyright 2006, Wiley-Blackwell.

Cognitive Imprecision and Strategic Behavior

Measuring Attention and Strategic Behavior in Games with Private Information