Like DuRant, Lemish also found gender differences: girls seemed to be attracted to the violence they saw on the screen for social reasons, but they practised violence at home, with siblings, not at school with their peers. School principals confirmed an increase in incidents of violence. They described dozens of unreported admissions to hospital for fractures and minor concussions, and "hundreds of minor injuries involving visits to school nurses". They noted violence being practised on the playground and generally high levels of emotional distress. Lemish's study so heightened public concern that the issue of media violence was discussed in the Israeli parliament. The result was that one channel stopped broadcasting WWF programmes, and another moved the programme to a later hour and added a warning to it. One media researcher cautions against oversimplifying a complex problem. Cecilia von Feilitzen (Stockholm University, Sweden) believes there has been too much focus on the causal relations between media exposure and violence in society, with a failure to differentiate among different kinds of influences. She also argues that media can have positive influences on children's development. Von Feilitzen has summarised five common influences of media violence. First, many studies have focused on imitation and aggression. Small children often imitate what they see on television, as part of the socialisation process, but this does not necessarily make them more aggressive. Although "in the short and long term, media violence contributes to aggression", she said, statistical studies show it can explain only about 5-10% of children's aggression. Family, schools, personality, and society are far more important influences, contributing to 90-95% of aggression. Some kinds of media violence contribute to aggression more than others. Violence contributing most to aggressive behaviour tends to involve an attractive perpetrator, justified actions by a "hero", and depictions that are extensive or realistic, or which do not show the consequences of the violence.