A three-year study of the three major television networks shows decreasing violence in primetime and children’s programming, a university researcher said Tuesday.This indicates the Television Violence Act passed by Congress in 1990 is having an effect, said Prof. George Gerbner, leader of the team that conducted the study for the University of Pennsylvania’s Annenberg School for Communication. More details of the study were to be released at a news conference here today. Gerbner has been studying television violence since the 1960s. He has been an important contributor to congressional hearings on the subject and will be among the speakers at a major entertainment industry meeting on TV violence Monday in Los Angeles. He said the “violence index” developed by his research team shows that primetime dramatic program violence dipped in the 1989-90 season and, despite some fluctuation, has remained below its 20-year average. The study, which involved only ABC, CBS and NBC, showed Saturday morning children’s programs became somewhat less violent only last year. The TV Violence Act, due to expire in December, gave the networks an antitrust exemption to allow them to communicate with one another about reducing violent programming. As a result, the networks adopted program standards against using violence gratuitously, for shock value or with depictions of excessive gore or pain. They also agreed to put parental advisories on programs containing violence and to participate in the Los Angeles meeting. Gerbner’s report finds that 65% of primetime fictional dramas and nearly half their casts are still involved in violence. But the frequency of violent scenes per hour is about half of what it had been before 1990. Saturday morning children’s programs, traditionally the most violent, saw a slower, more uneven decline, he said. More than nine of 10 programs and eight of 10 characters are still involved in violence. In 1990, children’s programs were saturated with a record high of 32 violent scenes per hour. By the 1992-93 season, that rate declined to 18 violent scenes per hour, Gerbner said. He added that his research consists of monitoring network TV programs and determining their contributions to viewer perceptions of social reality. “The results show that heavy viewers are more likely than comparable groups of light viewers to express feelings of living in a mean world and the inclination to act accordingly,” he said. Collaborating with Gerbner in the study were Michael Morgan of the University of Massachusetts-Amherst and Nancy Signorielli of the University of Delaware. Assisting were Cynthia Kandra and Nejat Ozyegin.