video games + violence

Over the last years violent video games have become more and more realistic, is this promoting violence within people.

CALL OF DUTY
Call of duty is a very popular game it is very violent and could lead to people copyin the game and actually pysically killing someone you never know, it is a 18 but loads of people under the age of 18 play it which i guess is ok because people will just say its only a game but they dont realise that one day there could be big influences from the game which can then lead to big incidents. People get addicted to it and play it everyday and it is talked about alot so that must mean that it is highly influenced.

Anders Breivik
1st May 2012 a man named Anders Breivik from Norway was charged with 77 attempts of murder all because of call of duty as he used the game as a training aid he made the attacks in Oslo and Utoya.
This is an example of a very bad influence i was taking about so imagine if your kid was palying call of duty and had thought track of i wanna kill people going through is head what would your opinion on the game be?

What causes the violence
Violent behaviour can be caused when games are played alone, as the game player has no one to compete against.  This means that the aggressive behaviour encouraged by the game has no way of being used up and so it can be aimed at an object or person. If you play a cooperative game with another person then this means that the aggressive behaviour is used constructively during the game against the competitor.