Fight or flight? Defense participation is driven by the economic and social costs of leaving
One important reason that humans engage in intergroup conflict is to defend themselves against hostile outgroups. Previous work has identified several mechanisms that impact defensive aggression. Yet, the specific circumstances under which individuals are willing to join other group members to collectively defend against out-group aggression remains poorly understood. The current study aims to resolve this shortcoming by investigating the economic and social costs of defense participation.
Defense participation could be based on rational cost-benefit calculations, taking into account factors such as the cost of leaving and past conflict experiences. However, conflict participation could also be driven by social dynamics, as individuals are more likely to defend against outside hostility when they are in groups rather than alone.
In two experiments, we examined when and why defenders participate in defense. In both experiments, participants were instructed for the intergroup attacker-defender game, in which six participants were randomly divided in three-person attacker and defender groups. Participants received 20 resources. Thereafter, defenders were given the option to stay (and participate in conflict) or leave. If defenders left, they escaped the attack by the other group, but leaving was costly (i.e., defenders had to pay resources to leave). If defenders stayed, the defenders who stayed and all attackers could contribute their resources to conflict (or not). When attackers contributed more to conflict than defenders, the attackers appropriated the resources of the defenders who stayed. However, when defenders contributed more or equal resources to conflict than attackers, defenders survived and earned their non-contributed resources.
In the first experiment, we conducted an online survey (n = 132) and an interactive behavioral experiment (n = 240) in which we manipulated the economic costs of leaving. In the online survey, defenders indicated if they wanted to participate in conflict for each possible cost of leaving. In the interactive behavioral experiment, groups of attackers and defenders interacted in four blocks consisting of ten rounds each. Between blocks, we manipulated the cost of leaving. In experiment 2 (an interactive behavioral experiment, n = 240), we manipulated defenders’ ability to leave between blocks.
Results show that defenders were more likely to participate in conflict when leaving became increasingly costly and when they successfully defended themselves in the past, in line with the idea that they perform cost-benefit calculations. However, defenders stayed even when leaving was clearly the most profitable strategy for them, revealing that defense participation cannot be driven by purely rational cost-benefit calculations. Instead, defenders were most likely to stay when other group members could not leave. We further show that conflict participation was partly explained by social norms and individual preferences.
Defense participation could be based on rational cost-benefit calculations, taking into account factors such as the cost of leaving and past conflict experiences. However, conflict participation could also be driven by social dynamics, as individuals are more likely to defend against outside hostility when they are in groups rather than alone.
In two experiments, we examined when and why defenders participate in defense. In both experiments, participants were instructed for the intergroup attacker-defender game, in which six participants were randomly divided in three-person attacker and defender groups. Participants received 20 resources. Thereafter, defenders were given the option to stay (and participate in conflict) or leave. If defenders left, they escaped the attack by the other group, but leaving was costly (i.e., defenders had to pay resources to leave). If defenders stayed, the defenders who stayed and all attackers could contribute their resources to conflict (or not). When attackers contributed more to conflict than defenders, the attackers appropriated the resources of the defenders who stayed. However, when defenders contributed more or equal resources to conflict than attackers, defenders survived and earned their non-contributed resources.
In the first experiment, we conducted an online survey (n = 132) and an interactive behavioral experiment (n = 240) in which we manipulated the economic costs of leaving. In the online survey, defenders indicated if they wanted to participate in conflict for each possible cost of leaving. In the interactive behavioral experiment, groups of attackers and defenders interacted in four blocks consisting of ten rounds each. Between blocks, we manipulated the cost of leaving. In experiment 2 (an interactive behavioral experiment, n = 240), we manipulated defenders’ ability to leave between blocks.
Results show that defenders were more likely to participate in conflict when leaving became increasingly costly and when they successfully defended themselves in the past, in line with the idea that they perform cost-benefit calculations. However, defenders stayed even when leaving was clearly the most profitable strategy for them, revealing that defense participation cannot be driven by purely rational cost-benefit calculations. Instead, defenders were most likely to stay when other group members could not leave. We further show that conflict participation was partly explained by social norms and individual preferences.