It turns out that sadism, the idea that it sometimes feels good to hurt others, is part of human nature.
It's something psychology professor Daniel Jones of the University of Texas/El Paso calls "Everyday Sadism." That kind of sadism is what people express when they play games like Grand Theft Auto V.
He uses an unusual questionnaire to place his test subjects on a sadism "spectrum."
"So some of the statements would include things like, 'I love video games that have the most realistic blood spurts' or 'I love cage fighting where there is no escape.'"
And then, he uses a modified coffee grinder, and invites subjects, who don't realize they're being tested, to grind up bugs. He gives the bugs names like Muffin, Ike, and Tootsie. The bugs are not actually ground up, but it sounds like they are.
"Well, what we were interested in is, if we give people a whole bunch of options of different jobs they could do around the department, what type of person would choose to grind the bug and how many bugs would they choose to grind," says Jones. "And it turned out that a lot of the individuals that were high in sadism, not only chose to grind the bugs, but had a lot of pleasure doing so."
Jones says that in one experiment he ran himself, a participant personally asked him if they had more bugs the participant could grind when the study was over.
Most people turn out to be not dangerously sadistic, but there are some people who could definitely be characterized as prone to violence.
"I think there is a certain segment of the population, I don't have a specific percentage number for you, that you could expose them to all the violent media you want, but I don't think the person would ever develop violent tendencies. And then I think that there are people in the population that would need no encouragement - they're innately violent," says Jones. "And I think that the majority of us, I think [it's] how we were born and raised and then what we were exposed to."
Jones says there is work now going on to use brain waves to assess reactions to things like violent video games or bug grinding. The idea will be that if you can identify early those who have a tendency toward cruelty, you could offer them help, or at least NOT allow them to purchase weapons until they'd been given some kind of treatment.
Even though Jones acknowledges that might create some political challenges.