HERE ARE TWO FACTS to contemplate: 1) video games are a big part of the youth culture and a huge business in the U.S.; and 2) there is now clear, replicated evidence that violent video games are associated with increased aggression in children and adolescents who play them.

As many as 80 percent of school-aged children and adolescents have a video game in their home, and those who don’t certainly have access to games through their friends. In some circles, the release of new video games engenders the same widespread excitement that accompanied the introduction of the iPhone. And video games are not only a male phenomenon; though game developers were slow to realize it, females constitute a sizeable and growing segment of the market. The sale of video games in the U.S. exceeded $13.5 billion in 2006 and worldwide the video-game business is challenging aspects of the movie and music industries. Violent video games of the Grand Theft Auto series are the most successful ever, with sales worldwide approaching $2 billion.

In the last 10 years, the growth of video games has led to a parallel increase in the number of studies evaluating their impact on children and adolescents. Overall, the findings reported in the literature are cause for concern. Collectively, both individual studies and meta-analyses show that exposure to violent video games is correlated with academic problems, arguments with teachers, fights at school, more positive attitudes toward violent behavior, decreased empathy for victims and a more aggressive view of oneself. Laboratory studies of youths playing violent video games demonstrate substantial physiologic arousal and an increase in aggression-related thoughts and feelings during play. Current research is investigating associations among video game exposure, obesity and social isolation; researchers are also studying whether video games are actually addictive.

All these findings sound pretty ominous, especially to a society worried about random violence and terrorism. Where there is smoke, there is fire; why let video games become even more pervasive and pernicious? A sensible society should act while it can to protect impressionable youth from dangerous influences like video games!

Before we leap into action, here is another fact to contemplate. Between 1994 and 2001, the period just after the violent video games Mortal Kombat and Doom were introduced, and during which Playstation and Grand Theft Auto became popular, the rate of juvenile violent crime (murder, robbery, rape, and aggravated assault) fell 44 percent. In short, the boom in violent video games correlates with the sharpest decline in youth violence in many decades.

How can this be — aren’t these “facts” mutually exclusive? The answer to this apparent paradox is that correlation does not prove causation. When two things are correlated, it means that there is an association between the two; they tend to change together in the same or opposite directions. It is tempting to conclude that a change in one produces a change in the other, especially when such a conclusion validates our beliefs. In actuality, the direction of causation could just as well be the reverse of what seems to be common sense; correlational data cannot give us an answer. In this case, one could just as reasonably speculate that the popularity of violent video games has led to a decline in juvenile violent crime. One could flesh out that speculation by postulating that perhaps video games “drain off” aggressive energy that otherwise might fuel violent crime, in the same way that children’s imaginative play is a socially sanctioned outlet for aggressive impulses. Citing similar societal worries (of youth being corrupted) that occurred with the introduction of “penny dreadfuls” (lurid serials marketed to teenagers in the 1890’s), “moving pictures” and comic books would lend a historical perspective to the speculation. Ultimately, however, no matter what our personal beliefs are we have to admit that the scientific jury is still out regarding what is the real impact of violent video games on adolescent behavior.

In the meantime, parents need to be advised to deal with video games as they would any other parenting challenge. A shared video- game experience is a time to discuss values, to differentiate fantasy from real life, and to explore issues of gender, race, bullying and consequences of aggression. They should try playing video games together with their children, getting the children to show them how they work and discussing their strengths and weaknesses. Parents need to be aware of the video-game rating system and set limits on what games are appropriate for children at a given age.

As with any childhood passion, moderation is best for overall development, and parents can help by limiting the time spent playing video games, ensuring that the games are in a public space rather than the child’s room, and insisting that video games don’t displace homework, reading for pleasure, social events, or family dinners. Even if their children are technologically more advanced than they are, parents are mistaken to withdraw from involvement in the video-game controversies.

Gregory K. Fritz, M.D., an occasional contributor, is academic director at Bradley Hospital and editor of the Brown University Child and Adolescent Behavior letter.