THE debate over whether television programmers have a moral responsibility to show only righteous and non-violent material is the Hongkong version of a saga that has played in virtually every country where TV fare is not dictated by government. TV's intrusion into the home is such that it is always open to accusations of undermining family values and governments often come under pressure to interfere. The pressure comes from self-proclaimed guardians of public morality, such as the Fight Crime Committee, and - more importantly - from parents anxious about the effects of TV on children. There is a difference here: Notions of morality vary between cultures and broadcasters must judge what is acceptable in their own societies; the impact of sex, violence or foul language on children and suggestible adults is more worrying. Studies in the West have found it impossible to link violence on TV and rising crime rates. Copycat violence does occur but it is usually committed by disturbed individuals who might otherwise have committed other violent crimes. Most parents will know that TV fights are often the stuff of children's games but most children quickly understand the difference between game-playing and reality. A more worrying effect is that children, particularly the very young, may be upset by TV violence. TV stations must observe the guidelines forbidding excessive violent or disturbing material at family viewing hours. It is not TV's role, however, to be a baby-sitter. It is the responsibility of parents to ensure children do not watch unsuitable programmes. The off-switch or suitable videos provide the best insurance.