Sex differences in the aggressive behaviour of schoolchildren.

An observational study was carried out to investigate whether sex differences in aggression, found in pre-school children in free-play situations, would also be found at older ages in the classroom. Equal numbers of boys and girls, aged 6 and 11 years, were observed individually in their school classrooms for eight 5 min periods, carried out over several weeks. At 11 years of age, boys showed more physical aggression than girls, a finding which resulted from a few boys showing higher scores than the remaining boys and the girls; girls showed more verbal aggression. These sex differences were not found at 6 years of age. At both ages, there was a higher proportion of same-sex than opposite-sex encounters. These results are discussed in terms of the generality of sex differences in aggression, the possibility of a sex difference in the form of aggressive acts, and the sex of the recipient of aggression.