Robert J. Keeshan, better known as "Captain Kangaroo," the children's television show host, told a Senate subcommittee hearing yesterday that media violence leads to aggressive behavior, and called for measures to regulate violent television programs.

Keeshan, who also called for more educational programming, was joined at the Senate subcommittee on juvenile justice hearing by a D.C. teacher, kindergarten pupils, a CBS-TV representative and mental health experts.

The hearing was designed to give legislators some understanding of the effects of television violence. Subcommittee Chairman Arlen Specter (R-Pa.) said that several bills may be passed by Congress next year that could affect television programming, including a measure to give tax credits to corporations that donate funds for educational programs on the air.

Legislators are "very concerned" about shows that feature violent and risque behavior, Specter said, adding that "we are taking a hard look at soap operas in the afternoon" and X-rated cable television programs.

Action-packed shows that feature car chases, fights and shootouts also contribute to child abuse and other aggressive acts, the soft-spoken Keeshan said.

"Government has a role to play in this. Along with the First Amendment right, there are responsibilities. There is a vague, vague sense of responsibility to serve children," Keeshan said.

Keeshan said that parents should not let their children watch some shows and added, "Perhaps the greatest danger in media violence results from what I call the immunization factor. A steady diet of television viewing exposes our young people to considerable violence, dramatic violence."

But Philip Harding, vice president of the CBS network's office of social and policy research, said there is no conclusive research that directly links television violence and aggressive behavior.

"My own interpretation of 'copycat violence' is that there exists among certain individuals a level of emotional pathology which, given the appropriate trigger, necessarily manifests itself in violent and destructive ways," Harding said. "To the extent this trigger is an external one, it might be literally anything in the disturbed individual's environment."

Keeshan went on to say, "This diet of violence has, in my opinion, created an immunity to the horror of violence. The young child may even come to believe that the use of violence is justified in problem solving."

Jib Fowles, a University of Houston professor, said television violence does not lead to aggression, but serves as a catharsis for viewers.

"The fantasy mayhem on the television screen . . . helps the child to discharge tensions and animosities. The fantasy violence on their favorite programs very rarely translates into inappropriate or aggressive acts," Fowles said.

Mary Ann Banta, a teacher at the University of the District of Columbia's early childhood learning center, said, "Understand this about young children: An essential tool of their learning is imitating the behavior of those around them. Children learn by imitation and they practice their imitation in their play. It is through the children's play that the assortment of television characters invade my classrooms."