This training reached into the middle brain and flipped a switch. The part of the mammalian brain that wouldn't allow a person to kill another human being was reset, making soldiers more capable of doing their jobs, routing the enemy faster and, in the end, saving lives.
Unintentionally, this training regimen has migrated from the firing range to the living room. Take Counter-Strike or Crysis, for example. Players fire a weapon at a human target that falls down when it is "killed." It's the same type of training used to raise the firing rate of the army from 15 percent to more than 90 percent. With many tech-savvy kids and adults growing up playing first person shooters, this means an entire generation has unwittingly undergone this military conditioning.
But have we become killers?
People who raise the point that violent videogame players have received military combat conditioning often equate it with committing acts of violence, but correlation is not causation. It has never followed that going through this conditioning means that one is guaranteed to employ it.
This has to do with the part of the brain in which the conditioning occurs. What stops a normal, unconditioned person from killing another human being in combat is the mammalian brain, which is pure instinct - the higher, rational brain has nothing to do with it. An unconditioned person can want to kill someone, only to be rendered unable as his middle brain takes over during the moment of crisis.
It takes a high level of stress - whether out of anger, fear or any other source of adrenaline - for this transition to occur. If that stress does not exist, your higher, more rational brain remains in control of your actions. Even under the most stressful circumstances, there has to be the right context.
To demonstrate the importance of context, Grossman offers the case of a police officer who had his family and friends hold a fake gun so that he could practice disarming criminals. Each time his disarmed his subject, he would hand it back so that they could repeat the process. Later, when he found himself in a store as an armed robbery began, he struck out at the criminal and took away the handgun. Then, just as he had practiced hundreds of times, he handed it back. His middle brain did exactly what he had trained it to do, regardless of how irrational it was under the circumstances.
Violent videogames may have made us capable of killing - under a very specific set of circumstances - but they haven't conditioned us to be killers. It would be more accurate to say we have been psychologically enabled to use deadly force in a combat situation, whereas before we were not.
While we haven't been conditioned to be murderers, however, the Columbine and Virginia Tech shootings prove that some of us are capable of committing heinous acts of violence under ostensibly mundane conditions. There is a very serious problem here that needs to be addressed.