L'évolution des comportements d'agressivité physique de la petite enfance à l'âge scolaire : le rôle des relations d'amitié en début de scolarisation
The aim of the present dissertation was to investigate the prospective links between friendship relationships and physical aggression development during the early school years. Within a theoretical framework based on social learning, personality, attachment and socioconstructivist theories, we examined the unique and combined role of various dimensions of friendship quality, friends’ behavioral characteristics and child’s pre-existing vulnerabilities in regard to the persistence of young children’s physical aggression. Data from the Quebec Longitudinal Study of Child Development (QLSCD), from the Quebec Newborn Twin Study (QNTS) and from an efficacity test through a dyadic intervention program were used. Measures in this dissertation were collected from kindergarten to grade 2, when the children were aged from 5 to 8 years old, with the children themselves, their friends, their classmates, their parents, as well as their teachers, through various questionnaires, a peer evaluation procedure and hypothetical scenarios.       In line with the social learning perspective, friends’ aggression was linked to a significant increase in children’s physical aggression. However, in line with the social bonding perspective, a good friendship quality played both a compensatory and a protective role, by respectively reducing children’s initial level of physical aggression and by mitigating the associations between friends’ and children’s physical aggression. Results also show that friendship conflict was associated to a linear increase with boys’ but not with girls’ physical aggression over time. Shared positive affect and conflict resolution skills were found to mitigate the prospective association between friendship conflict and children’s physical aggression. These results were independent of children’s sex and genetic risk for physical aggression. No interaction effects were found between the friendship dimensions and genetic risk for aggression, suggesting that children are equally affected independently from their genetic liability. Results showed an indirect effect of the dyadic intervention on decreasing levels of physical aggression through the improvement of one specific feature of friendship quality: conflict resolution. These results support the causal role of friendship quality on the developmental course of physical aggression and point to the inclusion of this relational aspect in prevention programs targeting young aggressive children.  Overall, the main and moderating effect found between friendship quality, friend’s aggression and child personal characteristics bring both theoretical and practical implications. Indeed, these results suggest that fostering a positive relationship between friends in the early school years may decrease physical aggression even if the friends are aggressive. Besides, high friendship quality may also buffer against the risk associated with experiencing conflict. These findings underscored the importance of taking into account the relational characteristics, such as conflict resolution and positive affect, in order to better understand the impact of friendship relationships on children’s physical aggression development.
Physical aggression Friendship quality Friends' characteristics Conflict Resolution skills Positive affect Genetic liability Early school years Prevention Peers