Violence in movies and video games has long been blamed for mass shootings and rising violence in society. But a new pair of studies finds that while we're watching more screen violence than ever before, that hasn't translated into more violence in society.

The new research was led by Christopher Ferguson, an associate professor of psychology at Stetson University in Florida. Ferguson has long argued that there is no good evidence that gamers or violent movie-watchers are inspired to commit crimes themselves.

In fact, some studies have found the opposite -- that playing violent video games can help certain people defuse their anger.

Ferguson led two studies that appear in the Journal of Communication. The first looked at movie violence and murder rates between 1920 and 2005.

His team watched dozens of the most popular films from 1920 to 2005 and counted the frequency of violent incidents, as well as how graphic the violence was. They then matched up those rates to homicide rates in the U.S. for the same years.

They found that physical abuse was common in movies in the 1920s, but then fell during the Depression and Second World War eras, then began to rise again in the 1960s and particularly in the 1980s.

Looked at as a whole, however, there was no overall trend linking movie violence and murder rates. In fact, by the 1990s, homicide rates were starting to decrease even while violence in films increased.

The team also found that the violence in films has grown more graphic over time, particularly in the latter half of the 20th century. But again, that increase was not matched with an increase in violence in society.

The researchers did note that during the middle of the 20th century, the frequency of violence in film rose at the same pace as homicide rates in the U.S. Ferguson says that link may have led some to believe there was a larger trend at hand. But he says that’s likely what’s called an “ecological fallacy.”

“Sometimes, if you only look at relatively narrow bands of time, you can see correlations occur that have really nothing to do with either thing causing the other,” he told by phone.

“It just happens due to chance or because of irrelevant factors.”

Researchers have proposed many theories about why violence was high in the ‘60s, ‘70s and ‘80s, from cutbacks to policing and mental health services, to the spread of crack cocaine, to more controversial theories such as lead in gasoline.

To his frustration, the belief that film violence is fuelling real-life violence has stuck, Ferguson says, even as evidence has grown suggesting the link may not be real.

Video games and youth

The second study he conducted looked at video game consumption from 1996 to 2011 and violence rates among youth between the ages of 12 and 17.

That study found that while violent video game sales grew in that period, youth violence rates dropped.

“If games really were having the dramatic effect that some people claim, we ought to be seeing a lot more violence spilling into society. And we’re really not,” Ferguson said.

On the other hand, there's no reason to believe that increased video game use has led to the decline in youth violence.

“I don’t think there’s anything causal there,” he said, calling the finding “likely another ecological fallacy.”

Today’s concerns about video games or movie violence are similar to those of previous eras, when many contended that rock and roll was corrupting young people, or that television or comic books were rotting children’s minds.

Ferguson said there has not been a lot of research to back up today’s concerns about media violence. Even studies looking at the immediate effects of watching blood-filled video games or films have reached conflicting conclusions, he said.

“The short term, experimental research has been all over the place and it’s very difficult to make any kind of definitive conclusion based on that research,” he said.

Interestingly, Ferguson said some studies have found people do indeed become desensitized to violence in movies, TV and games the longer they watch it. But he says there’s no evidence that that desensitization transfers to real life.

“It doesn’t seem to be the case that watching a lot of fictional violence necessarily make you less sympathetic to violence going on in the real world” he said.