Sex differences in frequency and level of physical aggression have been consistently reported. Scientists have proposed both social and biological explanations for this difference. Indirect verbal aggression is more common in girls than in boys. It involves seeking to harm the person's reputation or social standing, and may include social ostracism. Factors influencing both types of aggression are explored.
Richard E. Tremblay is Canada Research Chair in Child Development, professor of Pediatrics/Psychiatry/Psychology, and director of the Research Unit on Children's Psychosocial Maladjustment at the University of Montreal. Since the early 1980s he has been conducting a program of longitudinal and experimental studies, focusing on the physical, cognitive, emotional, and social development of children from conception onward, in order to gain a better understanding of the development and the prevention of antisocial and violent behavior. Director of the Centre of Excellence for Early Child Development, he is a Fellow of the Royal Society of Canada, and the Molson Fellow of the Canadian Institute for Advanced Research.