As of November 2014, psychological studies have found no conclusive proof that violent video games cause behavior problems in children. For example, although a study published in March 2014 in Singapore found that children showed more aggressive behavior when they played violent video games for longer periods of time, a study published in August 2013 concluded that at-risk children are not aggressive after playing such games.
The March 2014 study claims children who played a lot of violent video games showed an increase in aggressive thoughts. These thoughts led to shoving, hitting and pushing three years after an inundation of video games. The same study concluded that children who play violent games for less time had a decrease in violent behavior.
Experts criticized this study as biased, because the children rated the violence of video games themselves. Child-behavior experts noted that even though violence in books, television, movies and video games has increased, youth violence has not shown a linear increase.
The August 2013 study showed violent video games such as "Halo," "Mortal Kombat" and "Grand Theft Auto" actually calmed the minds of at-risk teenagers and reduced bullying and aggressive behavior. This study followed 377 children with an average age of 13 and a history of depressive mental difficulties.
According to the Palo Alto Medical Foundation, approximately 97 percent of American adolescents play a video game at least once per day, either on a large console, tablet computer or smartphone. Of those, 50 percent of boys favored "M for Mature" games designed for people 17 and older.