Is a match a tool or does it spell danger? It all comes down to maturity and morals.  Easy yet complicated when factors like mental instability come into the equation.  As a child I never felt the need to light up anything but the candles and as a game player shooting all sort of things I enjoy myself up to a point, but would never think of using and pointing a gun at a person or animal for any reason.  There are a lot of violent films and books out there, but nothing comes quite so close to actually/virtually using weapons like video games!  As COLEKERN commented they can be a contributing factor, but there always is a far deeper problem with these individuals.   

Violence, shootings and massacres pre-date video games, what was their 'cause'?!... Mental is mental, dependant on countless variables. In theory a video game could be a trigger for someone but then so could an episode of 'Jersey Shore', it's very rare and is generally an unhinged person, not a contagious epidemic or extreme side effect.

Video games aren't to blame; the unsound mind is.

I think they may be a contributing factor, but that they can't cause that behavior on their own. I think there has to be something deeper.

If someone's role model is Sub-zero or Scorpion, I wouldn't expect no violence.

I have never thought video games were a link to violent behavior. If violent visuals had any connectivity to human actions, why are people not complaining about "violent" children's cartoons on television? You know, those old ones where characters are depicted blowing each other up and doing harsh things to one another for the sake of comedy. But you don't see any kids lighting matches or hitting their friends over the head with a mallet, do you? This argument has little foundation, in my humble opinion.

 Am I violent because I play video games? Or do I play video games because I'm violent? Being violent has to come from a desire to do violence. You have to want to hurt someone. There isn't a product in the world that can instill violence in someone where a desire to do harm doesn't already exist. That is the simple truth. You can argue that kids mimic wrestlers and ninjas all the time, but I would argue that in most cases it's just kids having fun without a real sense of how much these things can harm people. When it comes to mass shootings, we're talking about something else entirely. Nearly all of these incidents end with the attacker dead in a shootout with the police or by his own hands. These people have decided to hurt the world and throw their own lives away. That comes from a much darker place than where Bulletstorm and Mortal Kombat can take you.

Bah, I'm getting tired of this argument. Yes, videogames might have a link to violence when given to a person already with mental issues, but elseway? I think not. There has ALWAYS been violence in the world, it's just that now we have this "wonderful" media, which will make sure to report every single act of violence upon the land.

There's my two cents.

I dont think video games have anything to do with the violence. I would say that if all your kid does is play video games, maybe as a parent you should find a way to interact with your child. Its not natural to push away your time with your parents for a video game, well not if your child doesn't hate to be around you. When the day comes that parents and their children interact all the time violence will automatically decrease. Love is the answer :)  that's just my opinion. but you know what they say about those ;)

Studies are always nice to increase general knowledge, but the reason these politicians want the studies makes them pointless. I mean, seriously... What are you going to do? Ban violent games? The farthest you can go is giving games adult rates and only selling said games to adults. Restriction can't go any further.

There's no way to know for sure what the situation would be without videogames.  But I can say that if you look at the data, since 1990 the murder and overall violent crime rates have been cut in half.  

That time period roughly coincides with the time period that violent videogames have been available.  So if they do have a negative impact - and haven't actually contributed to reduced crime as I suspect - then at least we can tell that it is not significant enough of a negative impact to have prevented the murder and violent crime rates from falling sharply.

Why do I think that these games have actually helped reduce murders and other violent crimes?  It gives kids something to do when they're growing up that, while not necessarily positive, more importantly isn't negative.  

Without games, many of these people would have ended up in gangs, committing crimes, and setting themselves up for a life of more of the same.  If they're busy playing games at home on the other hand, then they're not out committing crimes.

Numerous study's have proven there is no link.

This topic is always full of illogical, fallacious, or otherwise asinine arguments. I'd like to state up front that I think banning video games is a poor idea. With that said, however, I find it just as foolish when people suggest we don't need more research or interpret "more research on video games" as "blaming video games." Uh, more knowledge is always a good thing. Furthermore, I make the following counter-arguments:

-I would posit that it is impossible or nigh-impossible to show causation between video games and violent behavior. It's kind of like trying to prove causation between happiness and being in love, a relationship common sense tells us is true. How would you even go about proving that beyond the correlation, though? Studying brain chemistry? There are just so many factors which go into happiness that it's impossible to isolate a single dependent variable, just as the OP said. What makes it even harder for violent behavior is that people are -very- rarely violent when being observed or otherwise in public. Anyone who grew up with a violent family member knows exactly what I'm talking about. So demanding this "causation" proof is more or less demanding the impossible. Video games -have- been shown to increase aggressive thoughts and tendencies, and I really don't see how any rational individual could fail to see a relationship between increased aggression and violence.

-Speak to any writing teacher in the last five years about boys and violent video games. I'm one of them. If I do any sort of free write exercise, boys who play violent video games will ALWAYS write about violence. In fact, they often do so with gusto. However. if I add the restriction, 'you are not allowed to include violence' a great many of them can write NOTHING. They just sit there and stare at their papers. I've witnessed this hundreds of times.

-I often see the argument, "Yeah but movies are violent, so why aren't we regulating them?" Or rather the implied, "If we don't regulate all potential sources of violence, then we should regulate none." This argument is stupid on so many levels. You often hear this argument with regards to alcohol and marijuana. "Alcohol causes more deaths, but it's legal, so why isn't marijuana legal?" So what? They're both negative. It's like if I had a bunch of bad habits: heroin, eating couch cushions, no exercise, unsafe sex, etc. and suggesting that if I can't manage to kick ALL the habits, well then I shouldn't bother with any of them.  Furthermore, there's a BIG difference between violence in film and violence in video games.  Consider Godfather, regarded by many as one of the best films ever made.  It's pretty violent.  But the context of the violence is WELL-established.  The violence is, as my writing teacher says, "earned."  The point isn't the violence.  Now consider call of duty.  The point IS the violence.  Pointing a gun at people and pulling the trigger is the meat of the game.  The narrative, which is often rather flimsy, exists solely to provide justification for the killing of people.

I love video games, including some pretty violent ones, and I'm certain they've helped me grow in some ways. Certainly they entertained me. But I would much prefer my kids to never play them. I would much rather they develop a love for reading or cinema or mountain biking or photography. This increased research is a good thing if it can provide additional information to parents.

you know....after some thinking, should we really pay as much attention to these guys?  I feel that the more attention we give them, the more they think their cause is just.

I don't think they will ever come up with a ban on video games, whether they find out if they are bad or not. They still have to overcome the first amendment if they truly want to ban them. Their momentum is great, but, if it goes to the supreme court, we will win.

I agree to the fact that we do not know for certain if video games affect human behavior, if I had to guess I would say no but despite this the governments should NOT mess with anything, let people play whatever they want, they can not come and forbid this things, let people play whatever they want but let them know that the consequences of their actions will be punished, that´s all they should do. And if they want to blame someone they should blame the parents of those psycopathic kids...

I have stated this elsewhere before, and I think it deserves notice.  Even if 10 mass shootings can directly be correlated to video game violence, that means out of say 10 million gamers that play those same games, only 1x10^-6% (0.000006%) of the gamers who play those games were negatively affected.  Should the other 99.999999% of responsible gamers be punished for the transgressions of a few misguided individuals?  I think not.  Psychopaths are going to fly off the handle one way or another, despite what actions congress or any other entity may try to implement to thwart stimuli that may be a catalyst.  I am not suggesting that everyone deserves free reign, and that these acts are entirely unavoidable, but surely video games are not the sole cause, otherwise these incidents would be far more common considering the huge numbers of gamers that play violent titles on a daily basis.

Basically, I think your reasoned and moderate approach is refreshing. However there is quite a lot of things we already do know about this topic, for a long time, more than you may be aware of. :)

This episode of Penn and Teller's Bullshit! also provides a compelling argument. I believe they are trustworthy with their evidence and have no reason to believe why either Penn or Teller would be biased about the issue: 

http://www.youtube.com/watch?v=_9gVO6Hgj38

I will also leave this here: http://au.gamespot.com/features/games-day-in-court-science-violence-and-the-law-6314963/ < Essential reading for anybody interested in this debate.

We can never know for sure, which is the correct perspective, which is the scientific approach. However, the overwhelming evidence, both through experiments and the scientific community as well as circumstantial evidence (statistics around the world) indicate that there is no link between violent video games and real life violence. An example of substantial evidence is this study that turned into a book: http://en.wikipedia.org/wiki/Grand_Theft_Childhood <I note that it was funded by the federal government for policy reasons.

Why isn't there a double standard? Everyone watches movies. Django Unchained was extremely violent, but people didn't complain. People blame games because they don't play them. Maybe violence in our culture does have bad effects, but you can blame movies and music just as much as you can blame games.

If only a person(in this case the culprit or shooter) would open up. Let them hear why they really do that. What's the reason why. Sadly, this doesn't come out in public because people are busy finding to point the blame at or the shooter(usually) commits suicide after the offense.

If video games causes a person to be violent then there will be lot of killers out there, right? Take for example GTA and Manhunt, how many people play this games? There are a lot of factors aside from video games. Don't blame it solely.

The violence in games shouldn't affect someone's mind unless they have mental problems or can't keep reality and fantasy apart. I play violent games all the time and you don't see me hurting anyone. The mind is a complex organ and it's hard to study how certain things affect the mentality of the person.

They should just strengthen the ratings systems.  If a parent buys an M rated game for a minor they should be prosecuted.  Problem solved. 

http://www.ted.com/talks/daphne_bavelier_your_brain_on_video_games.html

found the link to the TED talk, she talks about the broad effects of video games,  so, to get any info that is relevant takes watching a fair part of this video.

this link is in reference to my first comment near the bottom of the page

They're delusional and more than likely they don't play video games so they chastise it.   Idiots they are ~ 

Take out ya stress on video games or take out ya stress on people, give the taliban a ps3 with ps+ and they will be like hudists by the end of the month... " shall we kill anyone?,"no have to hit lvl 50 by the end of the day".

With the lack of really solid, long-term studies, I have a hard time buying the argument that there is a clear connection. I'm probably in the higher end of age groups (45yrs old) for people that play video games, violent video games, and the only thing I can say is back when I was a kid, we grew up playing Cowboys & Indians, we ran around with replica  guns that made noises and looked very real, pretending to shoot each other. We were told playing that would make us violent. As we got older we transitioned into Dungeons & Dragons, we were told by church groups, parents and the media that this "violent" board game would turn us all into murderers. Finally, video games came into the equation and from almost day one the background noise was telling us once again that they would turn us in to horrible, violent people.

My friends are all now in our mid to late 40's, have never been arrested or had any major trouble in our lives. Oh, and we have never stabbed, slashed, hacked or shot anybody. Sure, games are different now, but the games I played as a kid for very different than what my parents and grandparents grew up playing too.