Sibling Aggression: Associations with parenting styles, social dominance behaviour and co-occurring forms of family aggression

Abstract

The thesis aimed to explore the experience of sibling aggression. Previous research has focused on the prevalence, predictors and effects of siblings engaging in aggressive behaviours with one another. However, there is a distinct lack of evidence that has explored the experience of this form of family violence. The thesis made an original contribution to knowledge by exploring the impact of multiple forms of family violence on the use of aggression between siblings, asking victims and/or perpetrators of these aggressive behaviours about their retrospective experiences and developing a quantitative measure of sibling aggression. A mixed methods approach was taken, employing archival, qualitative and quantitative techniques. More specifically, an archival study of the 1975 National Family Violence Survey (NFVS; Straus, Gelles & Steinmetz, 1980) was conducted to explore the relationship between co-occurring aggression and sibling aggression. The findings revealed that as co-occurring verbal or physical aggression increased within the family environment, the frequency of both physical and verbal aggression between siblings also increased. Following this, semi-structured interviews were conducted with victims and/or perpetrators of sibling aggression to explore this form of family violence further, particularly in relation to how aggression differs from play fighting, and the role of normalisation. The interviews identified that although aggressive acts of behaviour may look similar to those for play fighting, the motivations and functions of them differ. More specifically, play fighting was an enjoyable and game-like behaviour for children, whereas sibling aggression often occurred in response to a build-up of negative emotions, to maintain dominance or to overcome verbal arguments. The normalisation of sibling aggression was also important, particularly in relation to how parents responded to their children using aggressive behaviours with one another. In the third study of this thesis, a questionnaire, the Experiences of Sibling Aggression (ESA) scale, was developed to not only test the themes derived from the interviews on a larger scale, but to also explore differences between victims and perpetrators of this form of family violence. Amongst a sample of participants recruited through social media and on a university campus, a four-factor model of the ESA scale was validated, with subscales that reflected; play fighting, sibling aggression, normalisation and dominance. The ESA scale was also shown to increase the likelihood of predicting mutual sibling aggression, with these participants scoring higher on the sibling aggression subscale (concerning the use of aggression to overcome negative emotions and solve arguments) when compared to a control group of participants who had no previous involvement in aggression with their sibling.
These studies have provided several key contributions to knowledge of sibling aggression. Firstly, they have highlighted the relationship between sibling aggression and multiple forms of family violence. Secondly, they have enhanced the understanding of how play fighting and sibling aggression are conceptualised and differ from one another, highlighting the importance of parents in intervening in these behaviours. Finally, the ESA scale was developed, specifically for the exploration of this form of family violence. The implications of the findings involve the need to consider contextual factors rather than only the individual acts of aggression between siblings. It can be concluded that sibling aggression is a serious form of family violence serving a different function when compared to play fighting among children. This should be reflected in both practice and future research.