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Pressured to Attack: How Carrying-Capacity Stress Creates and Shapes Intergroup Conflict

Periodic Reporting for period 1 - ATTACK (Pressured to Attack: How Carrying-Capacity Stress Creates and Shapes Intergroup Conflict)

Reporting period: 2018-08-01 to 2020-01-31

Throughout the history, what has been causing tremendous suffering is groups of people fighting each other. While behavioral science research has advanced our understanding of such intergroup conflict, it has exclusively focused on micro-level processes within and between groups at conflict. Disciplines that employ a more historical perspective like climate studies or political geography report that macro-level pressures due to changes in climate and economic scarcity can go along with social unrest and wars. How do these macro-level pressures relate to micro-level processes?

With unavoidable signs of climate change and increasing resource scarcities, answers to these questions are urgently needed. This project considers carrying-capacity stress (CCS) as the missing link between macro-level pressures and micro-level processes. A group experiences CCS when available resources do not suffice to maintain its functionality (Fig. 1).
This project centers on the following three research objectives:

RP1: How macro-level pressures influence conflict within and between groups?
This research project centers around the hypothesis that carrying-capacity stress triggers out-group aggression and therefore links to increased levels of intergroup conflict. It entails:
(i) A systematic and quantitative review on the existing research involving macro-level pressures and intergroup conflict between and within societies.
(ii) An estimation of a directionality between carrying capacity stress and (aggressor-defender) conflicts between societies.. Carrying-stress capacity will be computed from: a) regional population dynamics, b) economic indicators such as food prices) climate-related indicators such as surface temperature.

RP2: Does carrying-stress capacity promote aggression between groups? This research project focuses on the causal impact of carrying-stress capacity on inter-group conflict. It entails laboratory experiments using Intergroup Aggressor-Defender Contests, testing whether outside pressures can create, a need to coordinate out-group aggression through enhanced communication and leadership.

RP3: How carrying-stress capacity shapes the biobehavioral underpinnings of between-groups conflicts? z should be accompanied by variations in individual-level neurophysiology. We center on the hypothesis that out-group aggression and in-group defense are associated with a specific pattern of neuro-, physio- and hormonal responses. We examine this possibility by means of “one-shot” Intergroup Prisoner’s Dilemma tasks.
The project recruited 3 PhD students, 2 postdoctoral students, and a part-time lab coordinator. A new research laboratory has been designed and built (funded by Leiden University) to facilitate psychophysiological measurement and behavioral experiments. Each team member has been assigned specific tasks within one of the three Research Packages. The team works together in various sub-groups on specific projects, meets once a week for collective laboratory meeting where work progress is discussed and tailored. No noticeable problems or set-backs have emerged.

First studies have been implemented and are, according to the schedule, currently in the data analysis or reporting phase. So far, results look promising, both confirming central hypotheses and opening-up new questions for future experiments and analyses. The PI has lead-authored two review articles that summarize the project’s background and research questions, and initial insights from the ongoing research (De Dreu & Gross, Behavioral and Brain Sciences, 2019a , 2019b; De Dreu et al., Trends in Cognitive Science, forthcoming). The latter paper develops the project’s novel perspective on group-living and intergroup relations, arguing that peaceful intergroup relations can deteriorate when individuals engage in parochial cooperation and parochial competition We identify three neurocognitive building blocks of parochialism—social categorization, in-group biased preferences and beliefs, and selective learning and updating. Whereas parochial cooperation is associated with neurobiological systems related to social bonding and perspective-taking, parochial competition is associated with neurobiological systems related to self-preservation and within-group status-ranking.

Three recent research papers successfully tested core predictions of the project’s proposalIn Gross and De Dreu (2019;under review) we considered that alone and together, climatic changes, population growth, and economic scarcity create shared problems that can be tackled effectively through cooperation and coordination. Perhaps because cooperation is fragile and easily breaks down, societies also provide individual solutions to shared problems, such as privatized healthcare.But how does the availability of individual solutions affect efficient creation of public goods? We confronted groups of individuals with a shared problem that could be solved either individually or collectively. Across different cost-benefit ratios of individually versus collectively solving the shared problem, individuals display a remarkable tendency toward group-independent, individual solutions. In the presence of individual solutions to shared problems, groups struggle to balance self-reliance and collective efficiency, leading to a “modern tragedy of the commons.” In De Dreu et al. (under review) we pushed these insights further by manipulating environmental threat and examining within-group cooperation in the context of intergroup conflict. We argue that natural and economic instabilities create unpredictable environments and have been associated with societal disintegration. Here we show that environmental unpredictability can foster an association between increased in-group cooperation and out-group hostility. In intergroup contest experiments, when the environment turned unpredictable, individuals felt more justified to exploit another group and contributed more resources to out-group attack. Individuals facing lower probability of environmental hazard stood by group members facing higher risk when contributing to out-group attack. Our results suggest that unpredictable environments associate with societal disintegration because they drive people together in cohesive groups marked by parochialism, polarize intergroup relations, and increase the probability of costly intergroup conflict.
Initial results are promising and in line with the project’s main working hypothesis. A large-scale cross-cultural project is currently being designed, to be implemented in Fall 2020. The core question addressed in this project is to what extent climatic, economic and socio-cultural variables at the level of countries drive propensity for in-group defense and out-group attack. In addition, on-going projects are currently examining the possibility that carrying capacity stress can be resolved through within-group innovation. A formal game-theoretic model is developed to test targeted hypotheses.

At the proximate inter-individual and individual levels of analysis (Fig 2) we have developed theory (De Dreu & Gross, 2019; 2020) and initial pilot testing has been performed to examine the neurophysiological underpinnings of parochial cooperation and competition during intergroup conflict. We expect first results to become available in 2020/21.
How carrying-stress capacity creates and shapes intergroup conflict.
A core perspective developed in the ATTACK project