In-group defense, out-group aggression, and coordination failures in intergroup conflict

Abstract

Intergroup conflict persists when and because individuals make costly contributions to their group's fighting capacity, but how groups organize contributions into effective collective action remains poorly understood. Here we distinguish between contributions aimed at subordinating out-groups (out-group aggression) from those aimed at defending the in-group against possible out-group aggression (in-group defense). We conducted two experiments in which three-person aggressor groups confronted three-person defender groups in a multiround contest game (n = 276; 92 aggressor-defender contests). Individuals received an endowment from which they could contribute to their group's fighting capacity. Contributions were always wasted, but when the aggressor group's fighting capacity exceeded that of the defender group, the aggressor group acquired the defender group's remaining resources (otherwise, individuals on both sides were left with the remainders of their endowment). In-group defense appeared stronger and better coordinated than out-group aggression, and defender groups survived roughly 70% of the attacks. This low success rate for aggressor groups mirrored that of group-hunting predators such as wolves and chimpanzees (n = 1,382 cases), hostile takeovers in industry (n = 1,637 cases), and interstate conflicts (n = 2,586). Furthermore, whereas peer punishment increased out-group aggression more than in-group defense without affecting success rates (Exp. 1), sequential (vs. simultaneous) decision-making increased coordination of collective action for out-group aggression, doubling the aggressor's success rate (Exp. 2). The relatively high success rate of in-group defense suggests evolutionary and cultural pressures may have favored capacities for cooperation and coordination when the group goal is to defend, rather than to expand, dominate, and exploit.competition | parochial altruism | coordination | collective action | intergroup relations

Pupil mimicry promotes trust through the theory-of-mind network

“…T he propensity to trust is essential for individuals to cooperate and for societies to prosper (1,2). Nevertheless, individuals also need to be equipped with decoding machinery in the brain, which allows them to quickly detect signals of danger (3), refrain from cooperation, and withhold trust (4). Among the many implicit cues that may inform assessments of someone's trustworthiness, the human eye region stands out as particularly salient and powerful.…”

Resolving attacker-defender conflicts through intergroup negotiation

“…Second, and possibly because of Behavioral and Brain Sciences these behavioral asymmetries, attackers are disproportionately less successful than defenders. Across a range of settings, from laboratory experiments to private sector competition to interstate warfare, we observed an attacker success rate averaging around 30% (De Dreu et al 2016a). Thus, the prevention of exploitation is more likely than subordination.…”

“…As in individual attack-defense conflicts, intergroup conflict often arises because attackers seek an improvement over their status quo that defenders seek to protect. Thus, such conflicts are captured as team-level variants of the Best-Shot/Weakest Link Game (Chowdhury et al 2013;Chowdhury & Topolyan 2016a;Note 4) and the Intergroup Aggressor-Defender Contest (IAD-C; De Dreu et al 2016a) in which individual contributions are modeled continuously rather than binary. For example, assume an equal number of members in the two rivaling groups, with N = N A = N D .…”

Does information about toughness decrease fighting? Experimental evidence

“…Here, subjects simultaneously wall sit and the winner, the person who endures longer in the position, takes the loser's money. In contrast to prior experiments on conflict, which typically use self-reported experience of fighting [62][63][64] or fighting as a potential loss of money [13,16,[65][66][67], our competitive wall sit captures key elements of real fights: it can be painful and requires both physical resilience and toughness.…”