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Leonard D. Eron, 87, studied violence

Leonard D. Eron, a psychologist whose pioneering studies of youth violence led him to conclude that television had a significant role in prompting destructive behavior in later life, died May 3 at his home in Lindenhurst, Ill., near Chicago. He was 87.

The cause was congestive heart failure, his family said.

In 1960, Mr. Eron began a long-term study of aggression in more than 800 children living in upstate New York. With two other clinical psychologists, Monroe M. Lefkowitz and Leopold O. Walder, and additional researchers, he interviewed 8-year-old children and their parents, evaluating behavior and opening a database to follow the children into adulthood. That work, which continues, became known as the Columbia County Longitudinal Study .

Rather than relying on asking the children about their own habits, Mr. Eron and his colleagues questioned their peers and asked them about threats, pushing, and other violent tendencies. They also interviewed parents about the television programs most often watched by their children, and rated the programs for their level of violence.

The Columbia County subjects were studied again in 1970, 1980, and 2000 (the most recent results followed 61 percent of the original participants), and the researchers found a correlation between the viewing of violent television shows in youth and the expression of violence in adulthood, in terms of criminal records and other measurements.

"Television has great teaching potential," Mr. Eron told The New York Times in 1993. "It's just been teaching the wrong things."

Mr. Eron and his collaborators also identified violent parents as another important factor in the development of overly aggressive children, and found that a long-term association between early exposure to violence, whichever the source, and aggression in later life held true for both sexes.

The study's findings have been widely cited, and although some critics pointed out that he had limited data on some of the long-term outcomes, Mr. Eron became a recognized voice on the subject.

He was president of the International Society for Research on Aggression from 1989 to 1991, testified before Congress on youth violence in 1992 and was co-editor of an influential 1986 research report, "Television and the Aggressive Child: A Cross-National Comparison."

L. Rowell Huesmann, a professor of communication studies and psychology at the University of Michigan, said Mr. Eron had became interested in ways to mitigate violence and the harmful effects of television. In the 1980s and 1990s, he helped prepare school programs in Chicago, neighboring Oak Park, and other cities to counsel children about how to deal with violent images. He also advised teachers and parents about the usefulness of encouraging positive behavior in students without placing undue emphasis on punishment for unwanted behavior.

Leonard David Eron was born in Newark. He earned his doctorate in clinical psychology from the University of Wisconsin in 1949. He taught at Yale and served as chief psychologist at the Rip Van Winkle Clinic in Hudson, N.Y., in the 1950s and early 1960s.

From 1962 to 1969, he was a professor of psychology at the University of Iowa. He later taught at the University of Illinois at Chicago, before moving in 1990 to the University of Michigan, where he was an associate dean for research at the School of Social Work. He retired in 2003.

He leaves his wife, Madeline Marcus, a former school psychologist; a daughter, Barbara of Lindenhurst; a son, Don, of Boulder, Colo.; and two grandchildren.