Is there too much violence on television and is it time to curb it? John Beyer, director of the organisation mediawatch-uk argues that media violence cannot be ignored.

Is there too much violence on television? Is there a connection between the violence shown on television and the increasing violence and aggression in our society? I think there is.

In his most interesting series, Child of our Time, on BBC1, Professor Robert Winston said: "The average British three-year-old is glued to a TV or computer screen for nearly five hours a day and almost half of all three-year-olds have a TV in their bedroom. Suddenly the outside world is coming into these children's lives."

He asked: "So does what they watch influence their behaviour? Most scientists now think that TV can encourage violent tendencies. Experiments show how dangerous seeing the wrong kind of lessons on TV could be on a child's developing idea of how to behave."

Following the release of the brutally and senselessly violent film Natural Born Killers, a BBC Panorama programme in 1995, entitled The Killing Fields, investigated cases in the US where the film had apparently played a role in influencing the commission of crimes similar to those portrayed in the film.

In the course of the Panorama programme a forensic psychiatrist, Dr Susan Bailey, was interviewed.

She said: "In the early 80s I encountered, over a five-year period, 20 youngsters who had murdered. A quarter of that group presented me with descriptions of how they had watched violent and pornographic films in the weeks leading up to their offence of murder – they described very vividly the films they had watched and how that had influenced their final act.

"The director of the film, Oliver Stone, who was also interviewed, said: 'Film is a powerful medium, film is a drug, film is a potential hallucinogen – it goes into your eye, it goes into your brain, it stimulates and its a dangerous thing – it can be a very subversive thing'."

More recently Natural Born Killers was cited by Lord Puttnam when he said that violent films breed bullies. He said: "We cannot afford to remain blind to the impact films and moving images of all kinds have on young people. You really are tinkering around in people's minds, imprinting emotions, messages and ideas which may well influence them for the rest of their lives."

The British Board of Film Classification, in its 1997 Annual Report, wondered "if Hollywood would ever wake up with a conscience about teenagers and the drip-drip effect of films which teach violence, glorify it and celebrate the rewards it brings".

Academic researchers, the Board said, analysed both the pleasures of violent entertainment and the dangers. They surveyed the prevalence of screen violence country by country. America has the highest crime rates in the developed world and produces the most violent entertainment. The most popular stars are the macho heroes who use violence and therefore demonstrate and validate its use.

The Economic and Social Research Council published findings in a report last November saying that robbers increasingly carry out vicious attacks for "kicks" and "street cred" to satisfy a desire for violence rather that for any financial gain. The father of Tom aps Rhys Pryce, who had been murdered in a street robbery, observed: "This seems to me to be a reflection of the world we live in, where violence is glorified in music, films and videos."

Computer games vie with each other to provide ever greater violence and ever more gory graphics, which the players gloat over. The most recent game to attract attention is entitled Rule of Rose. In November Franco Frattini, the EU Justice Commissioner, called for urgent action to limit the availability of "obscene" material to young people. The game puts the player in the shoes of a teenage girl who is repeatedly beaten and humiliated as she tries to break out of an orphanage. She is bound, gagged, doused with liquids, buried alive and thrown into the 'Filth Room'.

In the light of recent shootings in South London and the 'Gun Summit' held at 10 Downing Street, we again called upon broadcasters and film makers to embrace a much more socially responsible attitude to their portrayal of the use of firearms in their productions. Research carried out over many years by mediawatch-uk and others shows that the depiction of firearms being used in criminal ways is by far the most commonly portrayed violence on TV.

Our analysis of 107 films shown in 2006 identified a shocking 540 incidents involving firearms, 368 violent assaults and 180 incidents involving knives and other offensive weapons. The worst offenders were films such as Hard Target, New Jack City and Raw Deal on BBC1, Cliffhanger on ITV1, Natural Born Killers on Channel 4, Bad Boys, Dirty Harry, Heat and Young Guns on Five all repeatedly shown on the five terrestrial channels in recent years.

We believe that this level of fictional violence shown on television, which is consistent with our findings for the last 12 years, is unacceptable and irresponsible. From this quarter there has been a deafening silence and certainly no publicly announced undertakings to stop or even reduce the visibility of guns or other offensive weapons.

The regulator, Ofcom, too, has been silent despite the findings of its own research which states that 56 per cent of people say there is too much violence on television.

In the light of all the evidence and expert opinion it is curious, to say the least, that the film, television and games industries were not represented at the 'Gun Summit' and this, we believe, is a very serious omission. Harmful media influence cannot be ignored nor can the industries remain aloof or beyond criticism for the culture of violence to which they have contributed.

We welcome the emphasis now being placed by politicians upon family life and good role models. However, this new ethos must extend to film and television programme makers who must play their part in sustaining citizenship and civil society rather than setting models of behaviour that contribute to society's problems and undermine attempts to deal with them.

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