1. Team Games: Intra- and Intergroup Conflict Robert Böhm + and Ori Weisel § + RWTH Aachen University § University of Nottingham IMPRS Uncertainty Summer School Jena 2015

2. Attack vs. defense in intergroup conflict “Men rise from one ambition to another: first, they seek to secure themselves against attack, and then they attack others.” (Niccolo Machiavelli) “Do you know how I managed to unite moon worshippers, cannibals and giants into the same army? […] I told them they were all going to die unless they go south.” (Mance Rayder, Game of Thrones, Season 3, episode 2) Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham)

3. Attack vs. defense in intergroup conflict “Why, of course, the people don't want war. Why would some poor slob on a farm want to risk his life in a war when the best that he can get out of it is to come back to his farm in one piece? Naturally, the common people don't want war; neither in Russia nor in England nor in America, nor for that matter in Germany. That is understood. But, after all, it is the leaders of the country who determine the policy and it is always a simple matter to drag the people along, whether it is a democracy or a fascist dictatorship or a Parliament or a Communist dictatorship … voice or no voice, the people can always be brought to the bidding of the leaders... all you have to do is tell them they are being attacked and denounce the pacifists for lack of patriotism and exposing the country to danger. It works the same way in any country.” (Hermann Göring, Nuremberg Trials, 1946) Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham)

4. Attack vs. defense in intergroup conflict: The asymmetry hypothesis dominance of avoidance of potential losses over the achievement of potential gains (Kahneman & Tversky, 1984; Rozin & Royzman, 2001) threat motivates interpersonal aggression (e.g., Abbink & de Haan, 2014; Simunovic et al., 2013) larger motivation to participate in defensive rather than offensive intergroup actions attackers usually have the advantage of surprise, can retreat prior to an outbreak of violence, and typically risk only their own lives but not that of their relatives (Wrangham & Glowacki, 2012) defenders are probably outnumbered, and in case of a defeat not only their own live but also the lives of their relatives are in danger (Kelly, 2005; Rusch, 2013, 2014) Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham)

5. Attack vs. defense in intergroup conflict: The asymmetry hypothesis Both attacks and defenses produce public goods, but it is likely that the public good structure of attacks is partly undermined because attacks also produce private goods. Private goods may provide individual fitness advantages of participation in in intergroup conflict, e.g., individual advantages in sexual selection (Kelly, 2005; McDonald et al., 2012; Rusch et al., 2015). Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham)

6. Attack vs. defense in intergroup conflict: The asymmetry hypothesis Participation in intergroup conflict and individual fitness (Rusch et al., 2015)? Material No war: “John has been in the military for 5 years now. He is the leader of a unit consisting of 4 men. John and his unit have not yet been to a war zone during their employment in the military. They have stayed in the UK and are responsible for the coordination of military personnel and equipment.” War: “John has been in the military for 5 years now. He is the leader of a unit consisting of 4 men. John and his unit have been to Iraq recently. When they were there, their main job was the coordination of military personnel and equipment but they have also fought in a number of battles. After six months, John and his unit have returned home safely.” War with heroism: “John has been in the military for 5 years now. He is the leader of a unit consisting of 4 men. John and his unit have been to Iraq recently. When they were there their main job was the coordination of military personnel and equipment but they have also fought in a number of battles. After six months, John and his unit returned home safely. John was awarded a medal for individual bravery upon his return from Iraq.” Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham)

7. Attack vs. defense in intergroup conflict: The asymmetry hypothesis Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham) Rusch, Leunissen & Van Vugt, 2015 Evol. & Hum. Beh.

8. Attack vs. defense in intergroup conflict: The asymmetry hypothesis Is altruism more likely in defensive compared to offensive intergroup actions? Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham) Rusch, 2013 Evol. Psychol.

9. Attack vs. defense in intergroup conflict: The asymmetry hypothesis further anecdotal evidence regarding the primacy of defensive motivations in intergroup conflict: among the armed forces of nations, a considerable number has a name related to defense rather than attack according to the UN Charter of war (chapter VII, article 51), member states are only allowed to declare war for the sake of self-defense Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham)

10. Threat and the acceptance of parochial extremist propaganda Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham) Spiegel Online, August 5, 2015

11. Threat and the acceptance of parochial extremist propaganda Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham)

12. Threat and the acceptance of parochial extremist propaganda Mortality salience manipulation (Rosenblatt et al., 1989): “Please describe the emotions that the thought of your own death [control: failing an exam] arouses in you.” “Please describe, as specifically as you can, what you think will happen to you as physically die and once you are physically dead [control: failing an exam].” Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham)

13. Threat and the acceptance of parochial extremist propaganda Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham) Frischlich, Rieger, Hein & Bente, in press Front. Psychol.

14. Retaliatory outgroup hate: Experimental design (Böhm, Rusch & Gürerk, in press) Sequential IPD-MD: first-movers and second-movers Treatments: SEQ-BETWEEN: second-movers make contributions contingent on first- movers’ contributions to the between-group pool (using the strategy vector method; Selten, 1967) SEQ-WITHIN: second-movers make contributions contingent on first- movers’ contributions to the within-group pool (using the strategy vector method; Selten, 1967) Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham)

15. Retaliatory outgroup hate: SEQ-BETWEEN Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham) Böhm, Rusch & Gürerk, in press Evol. & Hum. Beh.

16. Retaliatory outgroup hate: SEQ-WITHIN Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham) Böhm, Rusch & Gürerk, in press Evol. & Hum. Beh.

17. Preemptive outgroup hate: Experimental design (Böhm, Rusch & Gürerk, in press) How do conflicts start in the first place? Treatments: SIM: standard (symmetrical) IPD-MD SEQ-PREEMPTIVE-STIKE: first-movers can reduce the negative effect of second-movers’ (potential) between-group contributions by harming them beforehand SEQ-SECURE-STRIKE: only first-movers – but not second-movers – have a between-group pool to invest Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham) First-movers’ contributions to between-group pool 012345678910-15 Potential loss for first-movers due to second-movers’ contributions to between-group pool 0.50.450.40.350.30.250.20.150.10.050

18. Preemptive outgroup hate Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham) Böhm, Rusch & Gürerk, in press Evol. & Hum. Beh.

19. Two pathways to ingroup defense: attack vs. peace-building (Böhm, Rusch & De Dreu, in pogress) In real-life intergroup conflicts, outgroup hate must not be the only behavioral option to decrease outgroup threat, but also peace-building by positive contributions to the outgroup is a viable strategy to protect the own group (e.g., tribute payments). Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham) behavioral option effect on…in-group defense decision maker in-group members out-group members keep+1.0 MU ––no within-group pool +0.5 MU –no (negative) between- group pool +0.5 MU -0.5 MUyes (positive) between- group pool +0.5 MU yes +0.4 MU yes +0.5 MU no +0.4 MU no

20. Two pathways to ingroup defense: attack vs. peace-building Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham) Böhm, Rusch & De Dreu, in progress

21. Two pathways to ingroup defense: attack vs. peace-building Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham) Böhm, Rusch & De Dreu, in progress

22. Asymmetric IPD (Weisel and Zultan) Attacker group can harm the Victim group Victim group cannot harm the Attacker group Payoff function of the attackers is like PD; depends only on ingroup contributions. Payoff function of the victims is like IPD; depends on ingroup and outgroup contributions. 3-person groups Endowment: 140 Contribution: 50 Effect: 30 Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham)

23. Social motives in intergroup conflict The effect of intergroup conflict on intragroup cooperation is typically attributed to enhanced group identity: “…enhanced group identity blurs the distinction between self-interest and group-interest, leading individual group members to substitute group regard for egoism as the principle guiding their choices.” (Bornstein and Ben-Yossef 1994) But group identity is not the only social motive involved in intergroup conflict: Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham) Group identityPredicts more cooperation in intergroup conflict ReciprocityPredicts more cooperation in intergroup conflict Social welfarePredicts less cooperation in intergroup conflict

24. Social motives - predictions Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham)

25. Framing Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham) Comparison frame Individual effect frame

26. Results Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham) The way conflict is framed is crucial when there is common fate. For pro-socials framing is also crucial in a single group game Comparison Individual effect Comparison Individual effect

27. Conclusions Framing matters If people perceive their group to be under threat, they are mobilized to do what is best for the group and contribute to conflict. If people perceive that they are personally under threat, they are mobilized to do what is best for themselves and withhold contribution. Robert Böhm (RWTH Aachen University) and Ori Weisel (University of Nottingham)