A new study provides the first experimental evidence that the negative effects of playing violent video games can accumulate over time.

Researchers found that people who played a violent video game for three consecutive days showed increases in aggressive behavior and hostile expectations each day they played. Meanwhile, those who played nonviolent games showed no meaningful changes in aggression or hostile expectations over that period.

Although other experimental studies have shown that a single session of playing a violent video game increased short-term aggression, this is the first to show longer-term effects, said Brad Bushman, co-author of the study and professor of communication and psychology at Ohio State University.

"It's important to know the long-term causal effects of violent video games, because so many young people regularly play these games," Bushman said.

"Playing video games could be compared to smoking cigarettes. A single cigarette won't cause lung cancer, but smoking over weeks or months or years greatly increases the risk. In the same way, repeated exposure to violent video games may have a cumulative effect on aggression."

Read more from Ohio State University.