Behavior in Group Contests: A Review of Experimental Research

Abstract

Group contests are ubiquitous. Some examples include warfare between countries, competition between political parties, team-incentives within firms, group sports, and rent-seeking. In order to succeed, members of the same group have incentives to cooperate with each other by expending individual efforts. However, since effort is costly, each member also has an incentive to abstain from expending any effort and instead free-ride on the efforts of other members. Contest theory shows that the intensity of competition between groups and the amount of freeriding within groups depend on the group size, sharing rule, group impact function, contest success function, and heterogeneity of players. We review experimental studies testing these theoretical predictions. Almost all studies of behavior in group contests find significant overexpenditure of effort relative to the theory. We discuss potential explanations for such overexpenditure, including the utility of winning, bounded rationality, relative payoff maximization, parochial altruism, and social identity. Despite over-expenditure, most studies find support for the comparative statics predictions of the theory (with the exception of the "group size paradox"). Finally, studies show that there are effective mechanisms that can promote withingroup cooperation and conflict resolution mechanisms that can de-escalate and potentially eliminate between-group conflict.JEL Classifications: C7, C9, D7, H4, J4, K4, L2, M5

Conditional cooperation in group contests

“…Further research should also reveal to what extent the findings depend on specific elements of the environment. Importantly, group contests come in many formats (see [15]) that may affect the behavior of the subjects, and our experiment uses just one of the standard contest setups. For instance, if instead of the lottery CSF the auction CSF is used (when the group with the highest performance wins the contest with certainty) and as a consequence the uncertainty involved in the determination of the winner is eliminated, subjects may be more willing to increase contributions as it is clearer how it augments the chances to win.…”

“…It is thus natural to assume that this behavior should at least partly explain how individuals behave in group contests, i.e., situations in which members of a group face a social dilemma when competing with other rival groups. [12][13][14][15] provide a nice introduction to the theory of group contest.…”

Leaders of war: modelling the evolution of conflict among heterogeneous groups

“…This shows that even when costs C and Pyr were frozen at default values (6 and 0.15, respectively), mean hawkishness (HD score) of populations increased from low FC, through default, to high FC conditions (table 3; N = 15 replicated iterations for each condition), suggesting that FC has an independent causal influence on HD. Our choice to treat all group member contributions as 'perfect substitutes' [28,[53][54][55], meaning that all individuals have equal capacity to contribute to a fight, could limit the generalizability of our results across different contexts of intergroup conflict. For example, in some taxa such as wolves and banded mongooses, some individuals (notably older males) have a disproportionate influence on conflict outcomes [85,86].…”

“…high interdependence between group members) and 'best shot' (e.g. champion warfare) group impact functions explore only the least and highest contributor, respectively [43,54,55]. Another approach, not explored in our model here, is to differentiate participation on the basis of attack or defence.…”

“…Models that consider this approach find differential investment depending on whether resources are being defended or attacked [87,88]. Nevertheless, a summed 'perfect substitutes' approach, as used in our own model, is the most widely used group impact function [54,55] and its use successfully captures many of the common elements of intergroup conflict (e.g. larger groups are more likely to win).…”