Chimpanzees, conflicts and cognition : The functions and mechanisms of chimpanzee conflict resolution

Abstract

In this thesis I studied conflict resolution in captive chimpanzees of the Arnhem Zoo, NL. Specifically, I investigated the occurrence and functions of various post-conflict strategies. Furthermore, I addressed the likely proximate cognitive and emotional mechanisms used in post-conflict interactions. I focused on two affiliative and two aggressive post-conflict interactions, namely reconciliation, consolation, further aggression and third-party aggression. Reconciliation, a friendly reunion of the opponents of an aggressive conflict, was influenced by relationship quality between the opponents. Relationship quality was also found to determine the amount of anxiety the opponents experience after conflicts. Anxiety was thus the likely emotional mediating mechanism in reconciliation. However, post-conflict anxiety and assessment of relationship quality were asymmetric between the opponents; only aggressees experienced stress and assessed relationship quality prior to reconciliation. Consolation, affiliation initiated by a bystander to a former conflict opponent, was investigated regarding its assumed function of stress reduction. I found no support for this function. Therefore, I renamed the behaviour as 'third-party affiliation'. Instead, I found that third party affiliation occurred more often when conflict opponents were likely to direct further aggression to bystanders and that third party affiliation effectively decreased the risk of receiving further aggression from the opponents. Hence, third party affiliation appears as a self-protection strategy from further aggression. The cognitive mechanism of third party affiliation has been assumed to be a cognitively empathic (emotional) concern of conflict opponents' distress. As third party affiliation was given for reasons that suggest self-regard, and in situations that do not require mental state attribution, it is unlikely that empathy underpins affiliation by bystanders. A possible exception is affiliation provided to conflict aggressees by their own relatives. This was not associated with self-protection and it was given in contexts that are likely to evoke empathic concern in the relatives. Thus, kin-related affiliation may be based on an empathic response. The aggressive post-conflict interactions were studied regarding their occurrence only. Third-party aggression was found to be an infrequent post-conflict interaction, for which I found no general determinants. Opponents were found to direct further aggression to bystanders after having won the conflict, which is against the previously known pattern of 'redirected aggression by victims', found in many species. I suggested that in chimpanzees further aggression may stem from an emotional process known as the 'winner-effect'. These four post-conflict interactions were found to occur largely independently from each other. Each of them is influenced by inter-connected emotional, psychological and functional aspects. In this thesis I scrutinized some of these aspects and found answers to some of the functional, emotional and cognitive levels of chimpanzee conflict resolution. My thesis emphasizes the complexity of chimpanzee conflict- and post-conflict behavior.