Leading Article: Why Arnie can't take the rap for juvenile violence

On Boxing Day BBC1 showed True Lies, a thriller starring Arnold Schwarzenegger. The film was bloody and action-packed. It was broadcast well after the "watershed", but even in the best-regulated households children are up and about over Christmas, so the movie was probably seen by many under-age viewers.

So what? Does it matter? Not a lot, is probably the answer. Real violence in the real world is what matters.

The questions that bother the police and the juvenile courts - let alone the rest of us as potential victims - have little to do with Schwarzenegger. Today we report research from psychologists at Birmingham University commissioned by the Home Office which, yet again, invites us to stop worrying so much about media effects and concentrate on causes. People use the media, not vice versa. People with violent dispositions seek out violent material. Films and videos do not cause hordes of otherwise level-headed people, young or old, to rush out into the streets brandishing an Uzi shouting "make my day".

Study after study since the late 1950s, based on samples large and small, have found no evidence that violence in film or television or video (this study concentrates on videos) is the specific cause of violent behaviour in viewers. That is not the same as saying that film violence has no effect. Common sense says it probably does: it probably causes considerable distress in many young minds, never mind adult ones. In others it probably triggers little imaginative response at all. Some people find fairground rides terrifying, others think they're a hoot. What's new? The justification for keeping video nasties out of children's reach (so far as that is possible) is the distress that may be caused. They are hardly likely to turn decent young people into vicious monsters.

Viewers, including children, bring to video and television their own expectations and standards. And the idea that television and video sends discrete "messages" is ridiculous. How, for example, to decode the fact that one night Schwarzenegger appears as ultra-violent action man, then the next (on Saturday in the movie Twins) as gentle giant with heart of gold? Viewers have no trouble dealing with a multi-layered fictional universe that has only a glancing relationship with reality.

The Birmingham research is non-committal on the question of effects because its principal finding is that violent videos are, so to speak, innocent parties. Young people with criminal convictions for violence seek out violent videos and view them much more intensively than either young people with non-violent convictions or young people in general. If you are looking for reasons why some children end up in court, what they watch on the screen is merely a symptom of their disturbance. This study confirms that children who become violent come from violent homes. There they acquire a predilection for physical confrontation; there, their moral sense is stunted.

If violent videos were banned it would make scant difference to the workload of the juvenile courts. Deprived of those videos young offenders and potential young offenders would find their role models elsewhere, from the pages of the newspapers, perhaps, pulp novels, or their violent mentors on the streets. Such a person is going to find out what he wants to know - indeed, the whole point is that he has probably already learnt more than anyone would want to know at his father's knee (or over it).

The lesson from this research is that violence is the issue, not videos as such. Preventing youth crime means addressing the trickiest of social policy questions: how and when to intervene in families that are dysfunctional, to prevent parents bringing children up in patterns of behaviour that are going to impose high costs on the rest of us, because we either become their victims or have to pay for their incarceration.

The public interest lies in emancipating children from the rule of parents who regularly use violence in the home. But the state is usually a poor instrument for bringing children up. State care can be equally abusive, not only in the obvious way, but also in the sense that children who are isolated from their natural community often react as isolated people do: angrily.

Intensive monitoring of problem families is costly. Yet casework based on the closest co-operation of teachers, health visitors, housing officials and social service departments is often the only way to mitigate the effects of parental delinquency. On Boxing Day, the problem was not that a violent film was shown on television, but that in too many households festivity will already have given way to routine aggression which the film might appear to validate.