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This thesis presents a series of studies investigating laterality in chimpanzees and its links with personality examined as behavioural style and social networks. The studies presented in this work were conducted by observing a group of 19 chimpanzees in captivity and present new findings in this species. However, this thesis has a broad evolutionary perspective, addressing important questions regarding personality and laterality that could prove helpful to the understanding of the evolution of laterality in vertebrates. Chapter 1 offers a general review of the three main areas of knowledge investigated: laterality, animal personality and primate social networks. Then, the first study of this project, presented in Chapter 2, began by exploring hand preference in the chimpanzee group, investigating spontaneous actions and unimanual tasks and expanding previous research by studying posture, between-task consistency and temporal stability. Chapter 3 investigated additional measures of motor laterality and proposed a novel way of measuring laterality in primates. Together, Chapters 2 and 3 directly examine laterality in chimpanzees and serve as the base from which to explore the links between laterality, personality and social networks in the subsequent studies. If lateralization is rooted in emotional processing and hemispheric lateralization, then individual differences in behaviour (particularly those that reflect emotional expression) would show a relationship with individual laterality. In order to address this question, Chapter 4 studies behavioural style in chimpanzees and its possible link with laterality. Simultaneously, if intraspecific coordination plays a role in the development of population level laterality, similarly lateralised individuals would likely have strong bonds to coordinate with each other. Chapter 5 introduces the approach and techniques of social network analysis and uses them to explore and describe the social structure of the group while describing the integration of a new adult chimpanzee. Chapter 6 applies social network analysis to explore if laterality plays a role in the way the group is structured. Lastly, Chapter 7 integrates all empirical chapters and presents the final discussion and conclusions of the thesis.

Bullying among school children is a social phenomenon that is now recognised as a widespread and serious problem across the globe. While decades of research have generated valuable insights as regards prevalence, main correlates and detrimental health consequences, many questions and gaps remain. For instance, it is unclear why the great majority of peer bystanders not intervene to support victims in a bullying conflict despite holding anti-bullying beliefs. Furthermore, great efforts have been made in the area of peer support and anti-bullying initiatives however there is still no intervention that has shown to be effective long term and cross-culturally. This thesis consists of two empirical studies. To advance knowledge of factors that influence pupils' victim support behaviour, the first study examined the role of perceived friend and peer consequences in predicting intentions to three types of help: provide emotional support, help to stop the bully and get adult support. Structural equation modelling revealed that perceived friend consequences were significantly associated with each of the victim support behaviours studied. Additionally, perceived peer reactions predicted intentions to get adult help. These findings suggest that friends play a more important role than peers in affecting victim support. Some significant gender effects emerged, showing that the overall pattern of associations held for boys, but not for girls. The findings highlight the concerns children hold with regard to their (dis)approving views related to victim support. Outcomes further suggest that victim defending should not be regarded as a broad homogeneous construct. The second study assessed the effectiveness of a cross-age teaching of social issues intervention (CATS) on enhancing pupils' knowledge on three victim support behaviours, and their awareness of the value of helping. In small cooperative groups older pupils were invited to step into the tutor role to prepare a lesson and teach it to two years younger tutees. An experimental-control group design was employed to test participants' performance at three time points over a six to eight week period. CATS tutors significantly improved their knowledge and awareness of the provictim behaviours studied while no positive changes were evident for participants in the control group. Furthermore, children who participated in the project expressed high satisfaction with the intervention. Based on the positive findings it was concluded that CATS is a viable technique for enhancing pupils' knowledge and awareness on prosocial topics. Helping children to see the value of supporting victims of bullying, in any of the ways studied, could help them avoid anticipating negative reactions from friends and peers, and in turn make it more likely that they would choose to help if the need arose.