Dr Kaj Bjorkqvist, his wife and research colleague Dr Karin Osterman, and their research team have conducted the major research into gender and developmental differences in aggression in school children. In particular, Dr Bjorkqvist and his colleagues are responsible for pioneering the measurement of indirect aggression, particularly in adolescent females. Dr Bjorkqvist is Professor of Developmental Psychology at Abo Akademi University in Vasa, Finland.