From Grand Theft Auto to Call of Duty, the world that video games often depict is full of violence and aggression that have no negative consequences for perpetrators or victims. Video game action is fast (and furious), and there is little or no time for contemplation of outcomes.

Sometimes the violence even appears to be energizing and fun. Injuries don’t hurt; victims don’t feel pain or sadness; and perpetrators don’t feel remorse.

So what is habitual exposure to this sanitized violence doing to our children? Does it change the way they think about violence or how they act?

Injuries don’t hurt; victims don’t feel pain or sadness; and perpetrators don’t feel remorse.

A recent study explored this question and came up with troubling conclusions. When children and teens routinely play violent video games, their thoughts and their behaviors become more aggressive. This happens regardless of their age, sex, empathy level, or monitoring by parents.

The study followed the game-playing habits and aggressive behavior of over 3000 eight- to 17-year-olds for three years.

Two groups, one in grades 3 and 4, and the other in grades 7 and 8, were the basis of the study. The children reported on the hours they spent gaming, their favorite games, and the content of the games. Researchers also rated the games for violent content using standardized measures.

The children were asked questions about their personal experiences of physical aggression, particularly in response to being provoked. For example, they were queried if they thought it was okay to respond aggressively to theoretical situations involving insults or aggravations and what aggressive or hurtful actions they might fantasize taking.

Finally, they were asked to interpret and respond to situations in which it wasn't clear whether someone was acting hostilely or aggressively and explain whether they thought the actions were intentional or accidental. Students’ empathy levels were also measured.

The results clearly showed that habitual violent video gaming increased aggression over the course of the study. Children in the study had more aggressive thoughts and fantasies and were more likely to rate hostile actions as intentional rather than accidental.

The Iowa State University researchers believe that changes in the amount of aggressive thinking came first and led to the increases in aggressive actions. A child's degree of empathy made no difference. All children experienced increases in their aggression levels from gaming exposure.

It didn't matter if parents monitored their child's game-playing either; children still became more aggressive from playing the games.

Although some have theorized that violent video gaming only affects those who are already high in aggression, this study showed that both high and low aggression individuals were affected similarly and all increased in aggressive thoughts and behaviors.

This study, published in JAMA Pediatrics, confirms many parents' worst fears. It has important implications for families raising children and teens, for health care and mental health providers, and for teachers and others who care for children.

Surveys have shown that over 90% of American children and teens play video games and that the content often depicts violent actions. In addition to increasing violent behavior, excessive video game use has been implicated in a wide variety of health problems including obesity.

The American Academy of Pediatrics recommends age-guided limits on the hours of screen time a child is allowed daily, as well as close parental surveillance of the nature of children’s exposures. Parents can obtain information about the target age, the content and the violence ratings of video games from websites such as the Entertainment Software Rating Board.