01/31/2013 07:40 pm ET Updated Apr 02, 2013

Trained to Kill: Two Marine Officers on Video Games and Gun Violence

The recent shootings in America are tragic. But by focusing mainly on gun control and mental health, our national debate thus far has overlooked a key factor in questioning why our youngest generation is so violent.

We are two former Marine infantry officers. Neither of us grew up around guns. In fact, until we joined the Marine Corps, we were adamantly opposed to them. But four years later, we look at gun control, violence and human nature very differently.

An essential part of our job as officers was to understand the psychology of killing -- how to train our Marines to kill, the ethical use of violence and understanding the implications of taking the life of another human. These were weighty issues for a group of teenagers and young 20-somethings. We owe a debt of gratitude to Lieutenant Colonel Dave Grossman (USA-Ret.), author of On Killing, for helping shape our views.

What we've learned: humans have a natural aversion to killing one another. It is a survival mechanism of the species. For example, General S.L.A Marshall's history of World War II showed that less than 20 percent of American soldiers fired on the enemy in combat. By Vietnam, that rate reached 95 percent. Our Marines in Afghanistan approached 100 percent.

What changed? Not biology or physiology. It was the psychology of how we trained.

After WWII, the Army found that even in war humans don't want to kill each other. Their solution to this problem was psychological conditioning designed to lower the natural aversion to killing.

The military started using human-shaped paper targets (similar to the silhouettes you can find today in shooting ranges across the United States), which later improved with technology. Human-shaped paper targets were replaced with human-shaped electronic targets that fell down when hit, simulating a dead enemy. The idea was to link reward centers in the brain to accuracy and the sight of a human falling down.

Many years later, the way we trained our Marines was even more advanced: we used real guns, equipped with paint bullets. We fought each other -- living, thinking, breathing enemies -- the ultimate in realism. Killing the "enemy" was fulfilling.

All of this has drastically lowered our resistance to killing when necessary, and yet even after all of our exposure to violence, we aren't unhinged psychopaths. Marines are ethical warriors, because an equally important aspect of our training is to learn about restraint. This comes through discussions, through readings, through heartfelt and emotional talks about what it means to kill someone. It all ties back to our core values of Honor, Courage and Commitment.

Here's the problem: children in America don't get that second set of lessons. They only get the first.

Consider some of the themes from Rockstar's Grand Theft Auto series: kill the cops, have sex with prostitutes, deal drugs and don't worry about consequences. And what's the big deal -- it's "just a game," right? At least, that was the argument we gave our parents a few years ago.

But we were wrong. Science has since proven that the brain rewires itself based on experience, and as Grossman has argued, violent video games break down a person's aversion to killing just like our training did. The realism provided by video games works on young brains the same way. Subconsciously, the person playing can't differentiate between the game world and reality. The result is that our generation is growing up with more exposure to violence and few, if any, of the lessons to understand it.

Yes, guns make it easier to kill people by increasing the physical distance from the target. Similarly, strangling is harder than stabbing is harder than shooting is harder than drone strikes. Also, guns have an enormous amount of power in a very small package. You can't perpetrate these kinds of mass murders with a knife.

But the issue is not as simple as more regulation, less regulation, different weapons, etc. The tools are not the problem. It's the people who use them. Any gun, in the hands of the wrong person, is a tool for evil.

So yes, America needs more gun control. It doesn't make sense that it's easier to buy a gun than it is to get a driver's license. But that's just one part of the solution. We also need to address the factors in our culture that promote violence.

Here's our perspective: Make guns harder to get. Don't take them from law-abiding citizens. But more importantly, focus on the contributing factors that motivate individuals to perpetrate these horrific crimes. We must re-evaluate the violent signals we're sending to our kids.

Michael Haft and Harrison Suarez are graduates of Washington University in St. Louis and former infantry officers in the United States Marine Corps. They served together in Helmand Province, Afghanistan during the summer of 2011 where they embedded with the Afghan Uniform Police and Afghan National Army. The views presented here are their own and do not reflect the Department of Defense or United States Marine Corps.