Despite its adults-only rating, many adolescents have thoroughly explored the criminal underworld of "Grand Theft Auto" and are eagerly awaiting the arrival of the fourth installment in the series, which will be in stores Tuesday.

Drive-by shootings, prostitution, robberies and car thefts make up just a few of the games' player activities. Advancing means committing criminal acts -- while trying to stay alive.

Sure, it's just a game, but what really happens physically and emotionally when an adolescent spends a great deal of time exposed to these activities?

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"Grand Theft Auto IV" follows Nikolai "Niko" Bellic, an Eastern European immigrant who gets dragged into a bloody criminal underworld.

Children are concrete thinkers, which means they often don't understand consequences, said Riverside family and marriage therapist Deborah Montana. For example, a young child who shoots another person may not fully understand that the act can result in real death, Montana said.

Games such as "Grand Theft Auto" reinforce this type of thinking with negative behavior that has no consequences, she said.

There is a term, vicarious traumatization, that describes the physical reactions a person can have after viewing a traumatic event, Montana said.

Habitual exposure to a violent event can cause a person to experience the same physical effects -- higher blood pressure, racing heartbeat, etc. -- as if the person were actually experiencing the event.

The same theory holds true for violent video games, Montana said. And the experience would be more intense for children, who are less psychologically mature than adults, she said.

"If you were someone that played this game for hours, I think it would really distort your world," Montana said.

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Rock Star Games

Advancing in "Grand Theft Auto" means committing criminal acts while trying to stay alive.

Another common problem is that younger siblings end up playing the game with their brothers or sisters, she said. Parents sometimes don't think to monitor the situation.

Craig A. Anderson, co-author of the book "Violent Video Game Effects on Children and Adolescents" has spent years studying the subject. In an article written for the American Psychological Association, Anderson wrote that repeated exposure to media violence:

"Creates aggressive behavioral scripts, making them more cognitively accessible."

"Decreases the accessibility of nonviolent scripts."

"Decreases the normal negative emotional reactions to conflict, aggression and violence."

Parents should use great caution in allowing adolescents to play any games designed for adults, said Temecula marriage and family therapist Raymond Cameron.

There is obviously good reason for the adult-only rating, Cameron said.

Reach Jennifer Dean at 951-368-9336 or jdean@PE.com