Contact: Daniel Nagin, PhD
(412) 268-8474
dn03@andrew.cmu.edu

Age Reduces Aggression In Boys

As boys grow older, they generally become less physically aggressive, oppositional, and hyperactive, according to a recent study by scientists at Carnegie Mellon University and the University of Montreal. This finding contradicts the popular belief that as boys age they increase the frequency of their physically aggressive and disruptive behavior.

"One of our purposes was to test different models of the trajectories, or paths, from problem behaviors in children to juvenile delinquency," said Daniel Nagin, PhD, who along with Richard Tremblay co-authored the study. "In the process, we found that many boys who had behavioral problems when they started school became better adjusted as they grew older. For example, only one in eight of the boys who were unusually physically aggressive in kindergarten was unusually physically aggressive in later adolescence."

The study, begun in 1984, involved 1,037 inner-city, nonimmigrant, Caucasian boys who lived in Montreal. Researchers assessed the boys seven times between the ages of six and 15 years to identify developmental predictors of physically violent and nonviolent juvenile delinquency. Information about behavior problems was collected from the boys' teachers during the 10-year study period, while information about delinquency was gathered directly from the boys and from official files. The results of the study appear in the latest issue of Child Development.

In addition, the study results indicate that boys who showed high levels of hyperactive behavior from kindergarten to high school were not nearly as at high a risk of juvenile delinquency as those who showed high levels of physical aggression or opposition.

"The implication is that hyperactive children without problems of opposition or physical aggression are not at greatly elevated risk for juvenile delinquency," said Nagin.

"Our results suggest that we need to look at behavioral development starting in the first year of life to understand better the early development of physically violent and nonviolent antisocial behavior," said Tremblay.

The research was funded by the governments of Quebec and Canada, the Molson Foundation, and the National Consortium on Violence Research.

###

Child Development is the bimonthly peer-reviewed journal of the Society for Research in Child Development. For information about the journal, contact Jonathan J. Aiken at (734) 998-7310.