Playing violent computer games can make you care less about violence in real life, according to a study.
Researchers watched a group of people playing games with brutal killings and high-powered weapons in them.
Then they showed them photos of real violence and found they were not as shocked by them as expected. They did this by monitoring their brains.
However, the group was still very shocked by other disturbing pictures of things like dead animals.
The scientists recorded how shocked the people were by looking at a certain type of brain activity, which measures how much effect a picture has on the brain.
People have tried to prove that violent games made people more aggressive in the past, but others said it was that more aggressive people simply chose games which were more violent.
One of the psychologists who did the survey, Bruce Bartholow, said: "As far as I'm aware, this is the first study to show that exposure to violent games has effects on the brain that predict aggressive behaviour."